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Different CFD results in 3D and 2D Axisymmetric geometry
Posted Nov 14, 2023, 4:42 a.m. EST Computational Fluid Dynamics (CFD), Geometry 0 Replies
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Hi,
I am running two simulations related to drag coefficients of a sphere. One simulation runs in 3D with a sphere in a cylinder, the other simulation runs in 2D axisymmetric with a half circle in a rectangle. Both of them have the same geometric relation such as size of sphere, position of sphere and size of cylinder. I apply the same physics (default laminar flow in COMSOL) and the same boundary conditions to both of the simulations. Vinlet=0.4m/s, p=0 at outlet, and non-slip wall for sphere.
For drag coefficient Cd=Cf+Cp where Cf is the friction coefficient and Cp is pressure coefficient
Vinlet is applied in Z direction and I want to derive the coefficients in Z direction.
please visit the link below to see the different results
1drv.ms/i/s!AnYEOGuLofRYg88qCRhOTIS01_sWBA?e=bFJccj"
Theoretically, The two simulations should have the same result.
But the results are quite confusing.
Cpz(3D)=Cpz(2D axisymmetric) => same
Cfz(3D)≠Cfz(2D axisymmetric) => unequal
Cdz(3D)≠Cdz(2D axisymmetric) => unequal
Is there anyone who can explain this to me? How can I derive the same result from axisymmetric geometry?
I can share my two COMSOL files if you want.
Thanks a lot
Hello BIYE CAO
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