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-   -   Low Mach number free-air condition (http://www.cfd-online.com/Forums/fluent/36209-low-mach-number-free-air-condition.html)

Riaan March 31, 2005 03:03

Low Mach number free-air condition
 
Hi guys,

I am running an airfoil at Low Mach numbers (M<0.05) in a "free-air" condition and having problems with steady state convergence.

The Boundary conditions are Pressure Far Field (and hence the Mach specification).I think maybe the solver has problems solving the compressible flow equations at such low Mach numbers -but because I am using pressure far-field, I must use Ideal gas i.e. compressible formulation.

Funny thing is, unsteady solver (2nd order implicit) seems to converge nicely.

Any advice?


dp March 31, 2005 11:15

Re: Low Mach number free-air condition
 
try the segregated solver

Riaan March 31, 2005 13:43

Re: Low Mach number free-air condition
 
Always been using Segregated.

Farid March 31, 2005 17:19

Re: Low Mach number free-air condition
 
Hi,

I think that as long as inside Fluent there is no low Mach preconditionning, and the solver is a usual Riemann solver, Fluent is unable to compute correctly low Mach flows.

It's a fact!!

Farid.


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