Abstr:Flow Around Finite-Height Circular Cylinder

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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


Front Page

Description

Test Case Studies

Evaluation

Best Practice Advice

References


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