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different results in 3d and 2d axis symmetric with same geometry |
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November 14, 2023, 04:32 |
different results in 3d and 2d axis symmetric with same geometry
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Billy Cao
Join Date: Nov 2023
Posts: 1
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Hi,
I am running two simulations related to drag coefficients of a sphere. One simulation runs in 3d Cartesian with a sphere in a cylinder, the other simulation runs in 2d axis symmetric 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 https://1drv.ms/i/s!AnYEOGuLofRYg88q..._sWBA?e=bFJccj Theoretically, The two simulations should have the same result. But the results are quite confusing. Cpz(3d)=Cpz(2d axis symmetric) => same Cfz(3d)≠Cfz(2d axis symmetric) => unequal Cdz(3d)≠Cdz(2d axis symmetric) => unequal Is there anyone who can explain this to me? How can I derive the same result from axis symmetric geometry? I can share my two Comsol files if you want. Thanks a lot |
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2d axis symmetric, 3d cartesian, drag coeffcients |
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