# Problem with vortex shedding frequency

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 September 26, 2014, 08:31 Problem with vortex shedding frequency #1 New Member   Saravana Kumar Lakshmanan Join Date: Feb 2013 Posts: 11 Rep Power: 13 Hi friends, I am currently trying to simulate flow past a circular cylinder for my thesis in OpenFOAM. I am having problem in getting the correct strouhal number. Drag coefficient is comparatively good. The following are the BC’s and details about mesh Dia=0.034 m; velocity=20 m/s; Re=45,000 ; Solver- PISOFOAM; RANS Model-kOmegaSST P-freestreamPressure at inlet & outlet, zeroGradient on cylinder (wall), Symmetry on Top & Bottom U-freeStreamVelocity at inlet & outlet, fixedValue (0) on wall, Symmetry on Top & Bottom k-fixedValue at inlet (based on k=3/2(UI)^2),zerogradient at outlet, FixedValue (0) on wall and kqrwallfunction, Symmetry on Top & Bottom omega-fixedvalue at inlet & outlet (based on omega=k^3/2/kcmul) basically took from one journal paper.For wall omega wall function and value =60nu/betaXdely^2. Symmetry for Top & Bottom nut-fixedvalue(0) at inlet, zerogradient at outlet,nutuspaladingwallfunction on wall, symmetry on Top and bottom. Mesh details: Y+=1, Four meshes are tested 50K,65K,80K,and 95K with max aspect ratio less than 22. The domain size is sufficiently long was used. fvSchmes: Time- Euler, gradschmes-Gauss linear, Divergence-Gauss limitedlinear,Laplacian-Gauss linear corrected Interpolation-linear, Sngrad-corrected Fvsolution: PCG with DIC as preconditioner for pressure with tolerance of 1e-06, reltol=0 For other terms PBiCG with DILU ,tolerance 1e-08 Ncorrectors=2,northogonalcorrectors=3 Please help me to solve this friends, Hope I described all important details

 November 19, 2020, 19:35 #2 Member   Chris Harding Join Date: Dec 2016 Posts: 76 Rep Power: 9 Hello, I wish I could help you, but I cannot. I am working on a tutorial that requires that the Strouhal Number be calculated and compared to literature. How did you calculate the frequency that is used to calculate the Strouhal Number? I appreciate any assistance you might have.

November 20, 2020, 06:16
#3
Senior Member

Santiago Lopez Castano
Join Date: Nov 2012
Posts: 354
Rep Power: 15
Quote:
 Originally Posted by aerosaravanan Hi friends, I am currently trying to simulate flow past a circular cylinder for my thesis in OpenFOAM. I am having problem in getting the correct strouhal number. Drag coefficient is comparatively good. The following are the BC’s and details about mesh Dia=0.034 m; velocity=20 m/s; Re=45,000 ; Solver- PISOFOAM; RANS Model-kOmegaSST P-freestreamPressure at inlet & outlet, zeroGradient on cylinder (wall), Symmetry on Top & Bottom U-freeStreamVelocity at inlet & outlet, fixedValue (0) on wall, Symmetry on Top & Bottom k-fixedValue at inlet (based on k=3/2(UI)^2),zerogradient at outlet, FixedValue (0) on wall and kqrwallfunction, Symmetry on Top & Bottom omega-fixedvalue at inlet & outlet (based on omega=k^3/2/kcmul) basically took from one journal paper.For wall omega wall function and value =60nu/betaXdely^2. Symmetry for Top & Bottom nut-fixedvalue(0) at inlet, zerogradient at outlet,nutuspaladingwallfunction on wall, symmetry on Top and bottom. Mesh details: Y+=1, Four meshes are tested 50K,65K,80K,and 95K with max aspect ratio less than 22. The domain size is sufficiently long was used. fvSchmes: Time- Euler, gradschmes-Gauss linear, Divergence-Gauss limitedlinear,Laplacian-Gauss linear corrected Interpolation-linear, Sngrad-corrected Fvsolution: PCG with DIC as preconditioner for pressure with tolerance of 1e-06, reltol=0 For other terms PBiCG with DILU ,tolerance 1e-08 Ncorrectors=2,northogonalcorrectors=3 Please help me to solve this friends, Hope I described all important details
What is the maxCourant?

 Tags cylinder, komegasst, pisofoam, shedding