https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&feed=atom&action=history Abstr:Flow in pipes with sudden contraction - Revision history 2024-03-28T20:28:21Z Revision history for this page on the wiki MediaWiki 1.39.2 https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=40464&oldid=prev Joe.Morris: Removed semantic markup. 2022-01-14T11:52:42Z <p>Removed semantic markup.</p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:52, 14 January 2022</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l25">Line 25:</td> <td colspan="2" class="diff-lineno">Line 25:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{UFR|front=UFR 4-14|description=UFR 4-14 Description|references=UFR 4-14 References|testcase=UFR 4-14 Test Case|evaluation=UFR 4-14 Evaluation|qualityreview=UFR 4-14 Quality Review|bestpractice=UFR 4-14 Best Practice Advice|relatedACs=UFR 4-14 Related ACs}}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{UFR|front=UFR 4-14|description=UFR 4-14 Description|references=UFR 4-14 References|testcase=UFR 4-14 Test Case|evaluation=UFR 4-14 Evaluation|qualityreview=UFR 4-14 Quality Review|bestpractice=UFR 4-14 Best Practice Advice|relatedACs=UFR 4-14 Related ACs}}</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">[[Category:Confined Flow|Flow in pipes with sudden contraction]]</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">{{#set:hasContributorOrg=ESDU}}</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">{{#set:hasContributorPerson=Francesca Iudicello}}</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">{{#set:hasQualityAccessLevel=SilverStar}}</del></div></td><td colspan="2" class="diff-side-added"></td></tr> </table> Joe.Morris https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=22273&oldid=prev Dave.Ellacott at 10:16, 19 October 2011 2011-10-19T10:16:25Z <p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:16, 19 October 2011</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l27">Line 27:</td> <td colspan="2" class="diff-lineno">Line 27:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Confined Flow]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Confined Flow<ins style="font-weight: bold; text-decoration: none;">|Flow in pipes with sudden contraction</ins>]]</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{#set:hasContributorOrg=ESDU}}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{#set:hasContributorOrg=ESDU}}</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{#set:hasContributorPerson=Francesca Iudicello}}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{#set:hasContributorPerson=Francesca Iudicello}}</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{#set:hasQualityAccessLevel=SilverStar}}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{#set:hasQualityAccessLevel=SilverStar}}</div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=10828&oldid=prev Niek.verhoeven at 10:40, 29 August 2009 2009-08-29T10:40:09Z <p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:40, 29 August 2009</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l28">Line 28:</td> <td colspan="2" class="diff-lineno">Line 28:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Confined Flow]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Confined Flow]]</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{#set:hasContributorOrg=ESDU}}</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{#set:hasContributorPerson=Francesca Iudicello}}</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{#set:hasQualityAccessLevel=SilverStar}}</ins></div></td></tr> </table> Niek.verhoeven https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=10738&oldid=prev Niek.verhoeven at 19:05, 28 August 2009 2009-08-28T19:05:28Z <p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:05, 28 August 2009</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l27">Line 27:</td> <td colspan="2" class="diff-lineno">Line 27:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[Category:<del style="font-weight: bold; text-decoration: none;">Underlying </del>Flow <del style="font-weight: bold; text-decoration: none;">Regime</del>]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[Category:<ins style="font-weight: bold; text-decoration: none;">Confined </ins>Flow]]</div></td></tr> </table> Niek.verhoeven https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=8848&oldid=prev Tonyh: Flow in pipes with sudden contraction moved to Abstr:Flow in pipes with sudden contraction 2009-04-07T14:29:11Z <p><a href="/w/index.php/Flow_in_pipes_with_sudden_contraction" class="mw-redirect" title="Flow in pipes with sudden contraction">Flow in pipes with sudden contraction</a> moved to <a href="/w/index.php/Abstr:Flow_in_pipes_with_sudden_contraction" title="Abstr:Flow in pipes with sudden contraction">Abstr:Flow in pipes with sudden contraction</a></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <tr class="diff-title" lang="en"> <td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:29, 7 April 2009</td> </tr><tr><td colspan="2" class="diff-notice" lang="en"><div class="mw-diff-empty">(No difference)</div> </td></tr></table> Tonyh https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=4664&oldid=prev David.Fowler: /* Abstract */ 2009-03-09T17:47:58Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:47, 9 March 2009</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l14">Line 14:</td> <td colspan="2" class="diff-lineno">Line 14:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A schematic of the flow through a pipe sudden contraction is shown in Fig.1. A notation of the terms used in this report can be found in the nomenclature section. In all flow regimes (laminar, transitional, and turbulent) the upstream fully developed flow conditions are not influenced by the contraction approximately 1-2 large tube diameters upstream of the contraction plane. Closer to the contraction plane the flow decelerates near the wall and accelerates in the central region. A separation occurs upstream of the contraction even at the low Re (the lowest considered here is ReD=23). See Fig. 2 for a sketch of the separation regions. With increase in Re, the upstream separation size (length and height) decreases slightly to reach a minimum value at about ReD=100. At around this flow condition the velocity profile immediately downstream of the contraction displays a velocity overshoot close to the wall with a magnitude higher than the centre line velocity. This flow feature is present at higher Re in the laminar, transitional and turbulent regimes. The upstream separation size increases with Re up to ReD=10&lt;sup&gt;4&lt;/sup&gt; and reduces slightly for ReD&gt;10&lt;sup&gt;4&lt;/sup&gt;. At ReD &gt; 300-400, a separation region develops immediately downstream of the contraction. The size of this separation increases with Re in the laminar and transitional regions. For Re&gt; 10&lt;sup&gt;4&lt;/sup&gt; the length of the separation reduces slightly with the increase in Re while the height is nearly constant.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A schematic of the flow through a pipe sudden contraction is shown in Fig.1. A notation of the terms used in this report can be found in the nomenclature section. In all flow regimes (laminar, transitional, and turbulent) the upstream fully developed flow conditions are not influenced by the contraction approximately 1-2 large tube diameters upstream of the contraction plane. Closer to the contraction plane the flow decelerates near the wall and accelerates in the central region. A separation occurs upstream of the contraction even at the low Re (the lowest considered here is ReD=23). See Fig. 2 for a sketch of the separation regions. With increase in Re, the upstream separation size (length and height) decreases slightly to reach a minimum value at about ReD=100. At around this flow condition the velocity profile immediately downstream of the contraction displays a velocity overshoot close to the wall with a magnitude higher than the centre line velocity. This flow feature is present at higher Re in the laminar, transitional and turbulent regimes. The upstream separation size increases with Re up to ReD=10&lt;sup&gt;4&lt;/sup&gt; and reduces slightly for ReD&gt;10&lt;sup&gt;4&lt;/sup&gt;. At ReD &gt; 300-400, a separation region develops immediately downstream of the contraction. The size of this separation increases with Re in the laminar and transitional regions. For Re&gt; 10&lt;sup&gt;4&lt;/sup&gt; the length of the separation reduces slightly with the increase in Re while the height is nearly constant.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>In order for CFD to predict reliably pressure losses in contractions, it is essential to capture the characteristic flow features for the whole range of geometries and flow conditions. The geometry range is defined by the contraction area ratio <del style="font-weight: bold; text-decoration: none;">s</del>: <del style="font-weight: bold; text-decoration: none;">0£s£1</del>. The flow conditions are characterized by ReD (or Red): laminar, transition and turbulent. In this work, two geometries were analysed with s=0.286 and 0.332. ReD was varied from 23 to 10&lt;sup&gt;6&lt;/sup&gt;.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>In order for CFD to predict reliably pressure losses in contractions, it is essential to capture the characteristic flow features for the whole range of geometries and flow conditions. The geometry range is defined by the contraction area ratio <ins style="font-weight: bold; text-decoration: none;">&amp;sigma;</ins>: <ins style="font-weight: bold; text-decoration: none;">0 &amp;le; &amp;sigma; &amp;le; 1</ins>. The flow conditions are characterized by ReD (or Red): laminar, transition and turbulent. In this work, two geometries were analysed with s=0.286 and 0.332. ReD was varied from 23 to 10&lt;sup&gt;6&lt;/sup&gt;.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:UFR4-14.gif|centre|thumb|440px|'''Figure 1.''' Schematic of the flow through a pipe with a sudden contraction.]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:UFR4-14.gif|centre|thumb|440px|'''Figure 1.''' Schematic of the flow through a pipe with a sudden contraction.]]</div></td></tr> </table> David.Fowler https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=3506&oldid=prev David.Fowler at 15:26, 6 March 2009 2009-03-06T15:26:33Z <p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:26, 6 March 2009</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{UFR|front=UFR 4-14|description=UFR 4-14 Description|references=UFR 4-14 References|testcase=UFR 4-14 Test Case|evaluation=UFR 4-14 Evaluation|qualityreview=UFR 4-14 Quality Review|bestpractice=UFR 4-14 Best Practice Advice|relatedACs=UFR 4-14 Related ACs}}</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{Status|checked=no|by= |date= }}</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Confined Flows==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Confined Flows==</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l19">Line 19:</td> <td colspan="2" class="diff-lineno">Line 23:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>----</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>----</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>''Contributors: Francesca Iudicello - ESDU''</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>''Contributors: Francesca Iudicello - ESDU''</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{{UFR|front=UFR 4-14|description=UFR 4-14 Description|references=UFR 4-14 References|testcase=UFR 4-14 Test Case|evaluation=UFR 4-14 Evaluation|qualityreview=UFR 4-14 Quality Review|bestpractice=UFR 4-14 Best Practice Advice|relatedACs=UFR 4-14 Related ACs}}</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Category:Underlying Flow Regime]]</ins></div></td></tr> </table> David.Fowler https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=376&oldid=prev Daveg at 14:50, 2 June 2008 2008-06-02T14:50:59Z <p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:50, 2 June 2008</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l4">Line 4:</td> <td colspan="2" class="diff-lineno">Line 4:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>====Abstract====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>====Abstract====</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Flow through ducts with sudden (sharp-edged) contractions occurs in many industrial applications. The flow separation in the vicinity of the contraction plane causes an increase in pressure loss, which affects erosion rates and heat and mass transfer rates at the separation and reattachment regions. In this work, the ESDU CFD predictions of the flow in a pipe sudden contraction were compared with the LDA measurements and numerical studies by Durst and Loy (1985) and Buckle and Durst (1993) for a contraction area ratio s=0.286, and Bullen et al. (1990; 1996) for a contraction area ratio s=0.332. The fluid was incompressible and Newtonian. The flow regimes were laminar, transitional, and turbulent (20 &lt; Re &lt; <del style="font-weight: bold; text-decoration: none;">106</del>). The CFD predictions of the pressure loss coefficient for these geometries and flow conditions were compared with the ESDU correlation (ESDU, 2001) for laminar and turbulent flows, and Bullen et al. (1996) measurements for turbulent flow.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Flow through ducts with sudden (sharp-edged) contractions occurs in many industrial applications. The flow separation in the vicinity of the contraction plane causes an increase in pressure loss, which affects erosion rates and heat and mass transfer rates at the separation and reattachment regions. In this work, the ESDU CFD predictions of the flow in a pipe sudden contraction were compared with the LDA measurements and numerical studies by Durst and Loy (1985) and Buckle and Durst (1993) for a contraction area ratio s=0.286, and Bullen et al. (1990; 1996) for a contraction area ratio s=0.332. The fluid was incompressible and Newtonian. The flow regimes were laminar, transitional, and turbulent (20 &lt; Re &lt; <ins style="font-weight: bold; text-decoration: none;">10&lt;sup&gt;6&lt;/sup&gt;</ins>). The CFD predictions of the pressure loss coefficient for these geometries and flow conditions were compared with the ESDU correlation (ESDU, 2001) for laminar and turbulent flows, and Bullen et al. (1996) measurements for turbulent flow.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Pipe contractions exist in a variety of process and chemical plants. In order to determine the overall pumping power in a piping system, it is essential to have reliable design procedures to predict pressure losses. It is also important to know the flow details of the separations upstream and downstream of the contraction plane to avoid placing sensitive equipment in these regions. The pressure loss through the contraction is caused by two consecutive processes: (1) contraction of the flow to the vena contracta, and (2) expansion to the wall of the small pipe. The latter is an “uncontrolled” expansion against an adverse pressure gradient. The smaller the area ratio, the larger the pressure gradient and hence the loss.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Pipe contractions exist in a variety of process and chemical plants. In order to determine the overall pumping power in a piping system, it is essential to have reliable design procedures to predict pressure losses. It is also important to know the flow details of the separations upstream and downstream of the contraction plane to avoid placing sensitive equipment in these regions. The pressure loss through the contraction is caused by two consecutive processes: (1) contraction of the flow to the vena contracta, and (2) expansion to the wall of the small pipe. The latter is an “uncontrolled” expansion against an adverse pressure gradient. The smaller the area ratio, the larger the pressure gradient and hence the loss.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>A schematic of the flow through a pipe sudden contraction is shown in Fig.1. A notation of the terms used in this report can be found in the nomenclature section. In all flow regimes (laminar, transitional, and turbulent) the upstream fully developed flow conditions are not influenced by the contraction approximately 1-2 large tube diameters upstream of the contraction plane. Closer to the contraction plane the flow decelerates near the wall and accelerates in the central region. A separation occurs upstream of the contraction even at the low Re (the lowest considered here is ReD=23). See Fig. 2 for a sketch of the separation regions. With increase in Re, the upstream separation size (length and height) decreases slightly to reach a minimum value at about ReD=100. At around this flow condition the velocity profile immediately downstream of the contraction displays a velocity overshoot close to the wall with a magnitude higher than the centre line velocity. This flow feature is present at higher Re in the laminar, transitional and turbulent regimes. The upstream separation size increases with Re up to ReD=<del style="font-weight: bold; text-decoration: none;">104 </del>and reduces slightly for ReD&gt;<del style="font-weight: bold; text-decoration: none;">104</del>. At ReD &gt; 300-400, a separation region develops immediately downstream of the contraction. The size of this separation increases with Re in the laminar and transitional regions. For Re&gt; <del style="font-weight: bold; text-decoration: none;">104 </del>the length of the separation reduces slightly with the increase in Re while the height is nearly constant.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>A schematic of the flow through a pipe sudden contraction is shown in Fig.1. A notation of the terms used in this report can be found in the nomenclature section. In all flow regimes (laminar, transitional, and turbulent) the upstream fully developed flow conditions are not influenced by the contraction approximately 1-2 large tube diameters upstream of the contraction plane. Closer to the contraction plane the flow decelerates near the wall and accelerates in the central region. A separation occurs upstream of the contraction even at the low Re (the lowest considered here is ReD=23). See Fig. 2 for a sketch of the separation regions. With increase in Re, the upstream separation size (length and height) decreases slightly to reach a minimum value at about ReD=100. At around this flow condition the velocity profile immediately downstream of the contraction displays a velocity overshoot close to the wall with a magnitude higher than the centre line velocity. This flow feature is present at higher Re in the laminar, transitional and turbulent regimes. The upstream separation size increases with Re up to ReD=<ins style="font-weight: bold; text-decoration: none;">10&lt;sup&gt;4&lt;/sup&gt; </ins>and reduces slightly for ReD&gt;<ins style="font-weight: bold; text-decoration: none;">10&lt;sup&gt;4&lt;/sup&gt;</ins>. At ReD &gt; 300-400, a separation region develops immediately downstream of the contraction. The size of this separation increases with Re in the laminar and transitional regions. For Re&gt; <ins style="font-weight: bold; text-decoration: none;">10&lt;sup&gt;4&lt;/sup&gt; </ins>the length of the separation reduces slightly with the increase in Re while the height is nearly constant.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>In order for CFD to predict reliably pressure losses in contractions, it is essential to capture the characteristic flow features for the whole range of geometries and flow conditions. The geometry range is defined by the contraction area ratio s: 0£s£1. The flow conditions are characterized by ReD (or Red): laminar, transition and turbulent. In this work, two geometries were analysed with s=0.286 and 0.332. ReD was varied from 23 to <del style="font-weight: bold; text-decoration: none;">106</del>.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>In order for CFD to predict reliably pressure losses in contractions, it is essential to capture the characteristic flow features for the whole range of geometries and flow conditions. The geometry range is defined by the contraction area ratio s: 0£s£1. The flow conditions are characterized by ReD (or Red): laminar, transition and turbulent. In this work, two geometries were analysed with s=0.286 and 0.332. ReD was varied from 23 to <ins style="font-weight: bold; text-decoration: none;">10&lt;sup&gt;6&lt;/sup&gt;</ins>.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:UFR4-14.gif|centre|thumb|440px|'''Figure 1.''' Schematic of the flow through a pipe with a sudden contraction.]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:UFR4-14.gif|centre|thumb|440px|'''Figure 1.''' Schematic of the flow through a pipe with a sudden contraction.]]</div></td></tr> </table> Daveg https://kbwiki.ercoftac.org/w/index.php?title=Abstr:Flow_in_pipes_with_sudden_contraction&diff=375&oldid=prev Daveg: New page: ==Confined Flows== ===Underlying Flow Regime 4-14=== ====Abstract==== Flow through ducts with sudden (sharp-edged) contractions occurs in many industrial applications. The flow separatio... 2008-06-02T14:47:46Z <p>New page: ==Confined Flows== ===Underlying Flow Regime 4-14=== ====Abstract==== Flow through ducts with sudden (sharp-edged) contractions occurs in many industrial applications. The flow separatio...</p> <p><b>New page</b></p><div>==Confined Flows==<br /> <br /> ===Underlying Flow Regime 4-14===<br /> <br /> ====Abstract====<br /> Flow through ducts with sudden (sharp-edged) contractions occurs in many industrial applications. The flow separation in the vicinity of the contraction plane causes an increase in pressure loss, which affects erosion rates and heat and mass transfer rates at the separation and reattachment regions. In this work, the ESDU CFD predictions of the flow in a pipe sudden contraction were compared with the LDA measurements and numerical studies by Durst and Loy (1985) and Buckle and Durst (1993) for a contraction area ratio s=0.286, and Bullen et al. (1990; 1996) for a contraction area ratio s=0.332. The fluid was incompressible and Newtonian. The flow regimes were laminar, transitional, and turbulent (20 &lt; Re &lt; 106). The CFD predictions of the pressure loss coefficient for these geometries and flow conditions were compared with the ESDU correlation (ESDU, 2001) for laminar and turbulent flows, and Bullen et al. (1996) measurements for turbulent flow.<br /> <br /> Pipe contractions exist in a variety of process and chemical plants. In order to determine the overall pumping power in a piping system, it is essential to have reliable design procedures to predict pressure losses. It is also important to know the flow details of the separations upstream and downstream of the contraction plane to avoid placing sensitive equipment in these regions. The pressure loss through the contraction is caused by two consecutive processes: (1) contraction of the flow to the vena contracta, and (2) expansion to the wall of the small pipe. The latter is an “uncontrolled” expansion against an adverse pressure gradient. The smaller the area ratio, the larger the pressure gradient and hence the loss.<br /> <br /> A schematic of the flow through a pipe sudden contraction is shown in Fig.1. A notation of the terms used in this report can be found in the nomenclature section. In all flow regimes (laminar, transitional, and turbulent) the upstream fully developed flow conditions are not influenced by the contraction approximately 1-2 large tube diameters upstream of the contraction plane. Closer to the contraction plane the flow decelerates near the wall and accelerates in the central region. A separation occurs upstream of the contraction even at the low Re (the lowest considered here is ReD=23). See Fig. 2 for a sketch of the separation regions. With increase in Re, the upstream separation size (length and height) decreases slightly to reach a minimum value at about ReD=100. At around this flow condition the velocity profile immediately downstream of the contraction displays a velocity overshoot close to the wall with a magnitude higher than the centre line velocity. This flow feature is present at higher Re in the laminar, transitional and turbulent regimes. The upstream separation size increases with Re up to ReD=104 and reduces slightly for ReD&gt;104. At ReD &gt; 300-400, a separation region develops immediately downstream of the contraction. The size of this separation increases with Re in the laminar and transitional regions. For Re&gt; 104 the length of the separation reduces slightly with the increase in Re while the height is nearly constant.<br /> <br /> In order for CFD to predict reliably pressure losses in contractions, it is essential to capture the characteristic flow features for the whole range of geometries and flow conditions. The geometry range is defined by the contraction area ratio s: 0£s£1. The flow conditions are characterized by ReD (or Red): laminar, transition and turbulent. In this work, two geometries were analysed with s=0.286 and 0.332. ReD was varied from 23 to 106.<br /> <br /> [[Image:UFR4-14.gif|centre|thumb|440px|'''Figure 1.''' Schematic of the flow through a pipe with a sudden contraction.]]<br /> <br /> [[Image:UFR4-14_a.gif|centre|thumb|440px|'''Figure 2.''' Sketch of the upstream and downstream separations in the vicinity of the contraction.]]<br /> &lt;br&gt;<br /> &lt;br&gt;<br /> ----<br /> ''Contributors: Francesca Iudicello - ESDU''</div> Daveg