Abstr:Flow Around Finite-Height Circular Cylinder
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
© copyright ERCOFTAC 2011