Low Mach number free-air condition

March 31, 2005, 03:03

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?

March 31, 2005, 11:15

try the segregated solver

March 31, 2005, 13:43

Always been using Segregated.

March 31, 2005, 17:19

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.

March 31, 2005, 03:03	Low Mach number free-air condition	#1
Riaan Guest Posts: n/a	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?

March 31, 2005, 11:15	Re: Low Mach number free-air condition	#2
dp Guest Posts: n/a	try the segregated solver

March 31, 2005, 13:43	Re: Low Mach number free-air condition	#3
Riaan Guest Posts: n/a	Always been using Segregated.

March 31, 2005, 17:19	Re: Low Mach number free-air condition	#4
Farid Guest Posts: n/a	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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