The purpose of this numerical simulation is to validate the following parameters of incompressible Large Eddy Simulation (LES) of flow over a cylinder:
The numerical simulation results of SimScale were compared with the experimental results. The flow regime selected for the study is classified as sub-critical with a flow reynold number of
The geometry of the study is a straight cylindrical body (see Fig.1.). A brief description of the dimensions is provided by the table below.
An O-type domain was selected as the flow domain around the cylinder. The domain was
in the radial direction and
in the span-wise direction (see Fig.2.). For this study a structured hexahedral mesh was created with the open source ‘BlockMesh-tool’. The grid nodes are distributed by a geometric grading in the radial direction. Further, the nodes are clustered near the stagnation point and in the wake region along the stream-wise direction. The mesh is based on a y-plus (
) criterion of
in the radial direction. The complete details of the mesh are listed in the following table:
Mesh and Element types :
|Mesh type||Cells in radial||Cells in circumferential||Cells in spanwise||Number of nodes||Type|
The numerical analysis performed is detailed as follows:
Tool Type : OPENFOAM®
Analysis Type : Incompressible Large Eddy Simulation
Sub-Grid-Scale Model : Smagorinsky with Cube-Root-Volume delta
The inlet boundary was set as a non-turbulent fixed velocity condition, while a pressure boundary condition was applied at the outlet. For the spanwise boundaries a symmetry condition was applied. The following table provides the further details.
|Wall no-slip||Fixed Value:
The numerical simulation results of mean pressure distribution and mean stream-wise velocity are compared with experimental data provided by C.Norberg  , L.Ong and J.Wallace  and L.M.Lourenco and C.Shih  . To ensure meaningful results, averaging was carried out over periods of atleast
time units or about 21 vortex shedding cycles.
A comparison of the mean pressure distribution obtained with SimScale and experimental results is given in Fig.3A. The mean stream-wise velocity profile is compared with experimental data as shows by the Fig.3B.
The instantaneous vorticity component
, and averaged streamlines in the cross-section (x-y plane) are shown by the Fig.4A and Fig.4B respectively.
A visualization of the instantaneous flow field is shown along the cross-sectional and spanwise planes provided by Fig.5A and Fig.5B.
|||L.M. Lourenco and C. Shih, ‘Characteristics of the plane turbulent near wake of a circular cylinder, a particle image velocimetry study’, Private Communication, 1993.|
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