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Vortex street. Flow around a cylinder.

Posted May 6, 2024, 7:46 a.m. EDT Fluid & Heat, General, Computational Fluid Dynamics (CFD), Mesh, Studies & Solvers Version 6.1 0 Replies

Joseba Martinez Lopez

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Hello everyone! I am facing a rare problem in a CFD model and I hope someone can enlighten me. I am modeling a 2D external flow around a cylinder. Laminar regime, Re=200, forming vortex street, computational domain is about 70D in streamwise direction and 20D in perpendicular direction. I am doing a mesh dependence study. Even with coarse meshes the error against experimental data I am comparing is fairly low, around 1%, and it improves with finer meshes. But here comes the interesting part, the finer the mesh, the later the vortex street appears. With the finest meshes, I have to model for more than 70 seconds for the vortex street to appear. When I use a structured mesh of quadrilateral elements, the vortex shedding does not happen, even with more than 120 seconds of simulation time (Before this I was using triangular elements). This does confuse me. Maybe is it the time step or CFL?

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