hello
I am doing thermal and hydraulic study of flow past perforated fins using turbulent K-Omega SST model in ANSYS Fluent. After few iterations, my Energy equation start to Diverge. Please suggest me, what should i do ?
Thanks and Regards
karthikeyan
try to amplify the relaxation on the speed and turbulence, if it doesn't work verify your Y+.
Divergence problem results mainly from improper meshing. Try to improve the mesh quality in the near wall regions. If problem persists, modify the turbulent boundary conditions at the inlet and outlets. Sometimes divergence arises from improper boundary conditions. Don't guess the boundary conditions, find some realistic boundary conditions available in the literature.
Dear Karthikeyan, may be following solution will help you:
(1) You can play with under-relaxation factor under solution control available in Fluent tab
(2) Run your simulation with First order scheme for few iteration than you switch to second order scheme.
(3) You can find appropriate solution method from literature (i.e for pressure-velocity coupling and for other)
(4) You also need to ensured mesh quality for your case
No matter how you change all the settings, a mesh with poor quality , always ends up with divergence. Try to improve the mesh quality. Sometimes lowering the under relaxation factor will help you.
Check the following
Follow the the steps and be free from DIVERGENCE !!
ALL THE BEST !!
As previously cited by Kannan, you can start with small values of C.F.L number and first order numerical schemes. In the second stage, you can switch to higher order numerical schemes with the higher values of CFL number (for steady state only).
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