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==== Abstract ====
==== Abstract ====
A low Reynolds number (Re=10000) flow around a NACA0012 airfoil with a Mach
The flow past finite-height cylinders mounted on a wall is of considerable practical and
number of Ma = 0.4 was chosen to test a new implementation in the CFD code.
fundamental fluid mechanics interest. It has numerous applications such as flow past
The flow is visualized with contours of velocity and pressure fields and the
cylindrical buildings, stacks or cooling towers, rods in various technical equipment, or
vortex street downstream of the airfoil is illustrated using the Q-criterion.
cylinders used as idealized vegetation or roughness elements in atmospheric boundary layers
Furthermore, the lift and drag coefficients are calculated.
and open-channels. The flow is very rich in featuring a variety of phenomena and is
The simulation was performed with the Finite Differences solver HiPSTAR (High
particularly complex as it is three-dimensional, highly unsteady and contains several
Performance Solver for Turbulence and Aeroacoustics Research), written mainly
interacting vortex systems. It is significantly more complex than the much studied flow past
by Richard D. Sandberg in Southampton.
long cylinders because of additional end-effects, both on the ground side and on the free-end
 
which interact with the vortex shedding that may prevail in the middle portion of the cylinder.
 
The Reynolds number is an important parameter already in the long-cylinder case; the
height-to-diameter-ratio ''h/D'' and the relative boundary layer thickness of the
approach flow, ''δ/h'', are
further important parameters in the finite-height case. A variety of experiments have been
carried out to study the influence of these various parameters and the flow configuration has
recently become a popular test case for large eddy simulations. The particular test case chosen
for this UFR is for cylinders with height-to-diameter-ratios ''h/D'' of 2.5 and 5
and a relatively
thin approach flow boundary layer having ''δ/h ≈ 0.1''. For these cases detailed LDV
measurements are available and also visualization studies and LES calculations that will be
compared with the experiments. The Reynolds number based on approach flow velocity and
cylinder diameter is 43000 in the ''h/D'' = 2.5 case and 22000 in the
''h/D'' = 5 case.
<br>
<br>
----
{{ACContribs
{{ACContribs
|authors=Paul Altenhoefer;Dominic von Terzi
|authors=Guillermo Palau-Salvador, Wolfgang Rodi,
|organisation=Universität Karlsruhe; Institute of Thermal Turbomachines;
|organisation=Universidad Politecnica de Valencia, Karlsruhe Institute of Technology
}}
}}



Latest revision as of 11:46, 14 January 2022

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Flows Around Bodies

Underlying Flow Regime 2-10

Abstract

The flow past finite-height cylinders mounted on a wall is of considerable practical and fundamental fluid mechanics interest. It has numerous applications such as flow past cylindrical buildings, stacks or cooling towers, rods in various technical equipment, or cylinders used as idealized vegetation or roughness elements in atmospheric boundary layers and open-channels. The flow is very rich in featuring a variety of phenomena and is particularly complex as it is three-dimensional, highly unsteady and contains several interacting vortex systems. It is significantly more complex than the much studied flow past long cylinders because of additional end-effects, both on the ground side and on the free-end which interact with the vortex shedding that may prevail in the middle portion of the cylinder. The Reynolds number is an important parameter already in the long-cylinder case; the height-to-diameter-ratio h/D and the relative boundary layer thickness of the approach flow, δ/h, are further important parameters in the finite-height case. A variety of experiments have been carried out to study the influence of these various parameters and the flow configuration has recently become a popular test case for large eddy simulations. The particular test case chosen for this UFR is for cylinders with height-to-diameter-ratios h/D of 2.5 and 5 and a relatively thin approach flow boundary layer having δ/h ≈ 0.1. For these cases detailed LDV measurements are available and also visualization studies and LES calculations that will be compared with the experiments. The Reynolds number based on approach flow velocity and cylinder diameter is 43000 in the h/D = 2.5 case and 22000 in the h/D = 5 case.



Contributed by: Guillermo Palau-Salvador, Wolfgang Rodi, — Universidad Politecnica de Valencia, Karlsruhe Institute of Technology


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