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-   -   Need help for solving Navier-Stoks equations (https://www.cfd-online.com/Forums/main/67717-need-help-solving-navier-stoks-equations.html)

mnabi August 24, 2009 19:06

Need help for solving Navier-Stoks equations
 
Dear all;

I am solving full NS equations by implicit-explicit method. I am applying Crank-Nicolson for diffusion, and second order Adams-Bashforth for convection term. But I am still annoying from a small CFL number. The time step becomes one order smaller than the smallest time scale of turbulence.

and my question: Is there any method to increase the CFL number, and at the same time conserve the second order of accuracy in time?

I tried Crank-Nicolson for both, diffusion and convection. But I am still annoying from a small CFL. Is CN method is not unconditionally stable for convection term?

Thank you in advance


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