# Convective flux scheme for rather low Mach number flow

 Register Blogs Members List Search Today's Posts Mark Forums Read

 December 12, 2012, 16:33 Convective flux scheme for rather low Mach number flow #1 Member   huaibao zhang Join Date: Feb 2011 Posts: 33 Rep Power: 7 Hi All, I am trying to simulate a long tunnel flow case, in which the flow stream conditions are: rho=0.3kg/m^3, T=1000K, p=10,000Pa, V=0.3 m/s. For testing, it is just a laminar case. I am developing a compressible flow code, so no such divergence free conditions at all. The density is changing. My question is for such low Mach=1.e-3, Re~1, which suitable convective flow scheme I should use? I tried Roe and Vanleer. The result is not satisfying . Thanks a lot. Paul

December 12, 2012, 17:15
#2
Senior Member

Filippo Maria Denaro
Join Date: Jul 2010
Posts: 2,517
Rep Power: 31
Quote:
 Originally Posted by paulzhang Hi All, I am trying to simulate a long tunnel flow case, in which the flow stream conditions are: rho=0.3kg/m^3, T=1000K, p=10,000Pa, V=0.3 m/s. For testing, it is just a laminar case. I am developing a compressible flow code, so no such divergence free conditions at all. The density is changing. My question is for such low Mach=1.e-3, Re~1, which suitable convective flow scheme I should use? I tried Roe and Vanleer. The result is not satisfying . Thanks a lot. Paul

I don't think the problem is in the convective scheme but in the ill-conditioned system... you need to use a suitable low-Mach formulation

December 12, 2012, 18:00
#3
Member

huaibao zhang
Join Date: Feb 2011
Posts: 33
Rep Power: 7
Quote:
 Originally Posted by FMDenaro I don't think the problem is in the convective scheme but in the ill-conditioned system... you need to use a suitable low-Mach formulation

I am not quite sure if I got your point. You mean I have to change my governing equations to make it work at low-Mach flow?

Thanks again.
Paul

December 12, 2012, 18:06
#4
Senior Member

Filippo Maria Denaro
Join Date: Jul 2010
Posts: 2,517
Rep Power: 31
Quote:
 Originally Posted by paulzhang I am not quite sure if I got your point. You mean I have to change my governing equations to make it work at low-Mach flow? Thanks again. Paul
In some formulations the equations are rewritten by using a pre-conditioner operator ... the problem with the low-Mach number is the stiff pressure condition you encounter (sound speed tends to infinity).
Many CFD textbook explain the problem

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Harkot FLUENT 3 October 1, 2013 11:04 Luiz Eduardo Bittencourt Sampaio (Sampaio) OpenFOAM Mesh Utilities 41 January 17, 2013 03:43 hit Main CFD Forum 2 October 26, 2009 22:21 Saif-Deen Akanni FLUENT 1 March 5, 2007 06:05 Endee FLUENT 8 September 7, 2005 16:16

All times are GMT -4. The time now is 05:51.