Transonic rhoSimpleFoam Equations

eric.m.tridas · January 16, 2012, 16:11

Hey Foamers,

I have read in several locations on this forum that rhoSimpleFoam is not suitable for steady transonic calculations (even though there is a "transonic" option

.) Has anyone had success in implementing new code/modifying the existing code to suit flows of all speeds with accurate results?

I found this paper through the forum:

http://powerlab.fsb.hr/ped/kturbo/op...E-JSME2007.pdf

That show that SIMPLE-like algorithms have been used in conjunction with OF to solve steady-state transonic cases by modification of the pressure correction equation (the author of the paper/post said the code would be available to the OF community... in 2007 - is this rhoSimpleFoam??).

I know I do not fully understand how the pressure correction equation in rhoSimpleFoam is implemented, maybe if someone could give me some information about this and a reference I could understand it better. Also if could someone explain why the equation code contained inside the if (simple.transonic()) { ... } is actually not applicable for transonic flows it would be quite helpful.

Sorry if this question is all over the place I'm just trying to understand what's really going on with this solver.

Thanks for your replies and input!

-Eric

schwermetall · January 25, 2012, 07:26

Hi eric,
I came across the same problem. You're are looking for a transsonic steady state solver right? From what I understand, this only works if you don't have regions with Ma > 1 as the equation type changes there. I can recommend the following book: Versteeg/Malalasekera 2008, p.36. There he writes:
" The transient version of the algorithm (SIMPLE) needs to be adopted to make use of the favourable character of parabolic/hyperbolic procedures."

If I understand that correctly, a steady state version is not possible. I used rhoCentralFoam in the end.

I hope that helps

Regards

vkrastev · January 25, 2012, 08:14

Hi all, if you want to better understand the alternative formulation of the pressure equation used in case of high Mach number flows, take a look at the following paper:

http://home.gwu.edu/~chliang/mae286/...peric_1993.pdf

If you are familiar with the incompressible SIMPLE-like procedure, it should be not that difficult to go through this one.

Best regards

V.

eric.m.tridas · January 25, 2012, 10:52

Hey V,

Thanks so much for your reply! I'll take a look at the paper.

-Eric

January 16, 2012, 16:11	Transonic rhoSimpleFoam Equations	#1
eric.m.tridas Member Eric M. Tridas Join Date: May 2011 Location: Tampa, Florida Posts: 48 Rep Power: 14	Hey Foamers, I have read in several locations on this forum that rhoSimpleFoam is not suitable for steady transonic calculations (even though there is a "transonic" option .) Has anyone had success in implementing new code/modifying the existing code to suit flows of all speeds with accurate results? I found this paper through the forum: http://powerlab.fsb.hr/ped/kturbo/op...E-JSME2007.pdf That show that SIMPLE-like algorithms have been used in conjunction with OF to solve steady-state transonic cases by modification of the pressure correction equation (the author of the paper/post said the code would be available to the OF community... in 2007 - is this rhoSimpleFoam??). I know I do not fully understand how the pressure correction equation in rhoSimpleFoam is implemented, maybe if someone could give me some information about this and a reference I could understand it better. Also if could someone explain why the equation code contained inside the if (simple.transonic()) { ... } is actually not applicable for transonic flows it would be quite helpful. Sorry if this question is all over the place I'm just trying to understand what's really going on with this solver. Thanks for your replies and input! -Eric

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January 25, 2012, 07:26		#2
schwermetall New Member Join Date: Aug 2011 Posts: 28 Rep Power: 14	Hi eric, I came across the same problem. You're are looking for a transsonic steady state solver right? From what I understand, this only works if you don't have regions with Ma > 1 as the equation type changes there. I can recommend the following book: Versteeg/Malalasekera 2008, p.36. There he writes: " The transient version of the algorithm (SIMPLE) needs to be adopted to make use of the favourable character of parabolic/hyperbolic procedures." If I understand that correctly, a steady state version is not possible. I used rhoCentralFoam in the end. I hope that helps Regards

January 25, 2012, 08:14		#3
vkrastev Senior Member Vesselin Krastev Join Date: Jan 2010 Location: University of Tor Vergata, Rome Posts: 368 Rep Power: 20	Hi all, if you want to better understand the alternative formulation of the pressure equation used in case of high Mach number flows, take a look at the following paper: http://home.gwu.edu/~chliang/mae286/...peric_1993.pdf If you are familiar with the incompressible SIMPLE-like procedure, it should be not that difficult to go through this one. Best regards V.

January 25, 2012, 10:52		#4
eric.m.tridas Member Eric M. Tridas Join Date: May 2011 Location: Tampa, Florida Posts: 48 Rep Power: 14	Hey V, Thanks so much for your reply! I'll take a look at the paper. -Eric