Flotran solver selection

AlloOoi · February 5, 2011, 11:54

Hi everybody,

I am a Bachelor student working on a problem using ANSYS Flotran (GUI) , which I am new in, to find the velocity and temperature distribution of air due to buoyancy effect under constant heat flux.
The analysis is for a simple 2D square model with the flux at one side and all other sides are at room temperature.
I have solved the problem using TDMA solver for pressure and temperature, for heat flux of 70 W/m2, and it worked properly. But when I solved it for heat flux of 70000 W/m2, the solution didn't converge and the program gave me this error message:
"Negative or zero temperatures may be avoided by either mesh refinement or modified inertial relaxation especially if Petrov-Galerkin formulation is used for the energy equation (FLDA,ENRG,SUPG,T)."
I tried to refine the mesh and change the relaxation factors but no use.
Can anybody help me to choose the appropriate solver for this problem with this high flux. Also if you have any other suggestions to converge the problem I appreciate knowing them.
Please reply soon.

ghorrocks · February 6, 2011, 06:04

Flotran died out long ago. Time to upgrade to a modern CFD solver. Your university probably has licenses of CFX or Fluent, so change to one of them.

February 5, 2011, 11:54	Flotran solver selection	#1
AlloOoi New Member Ali Baqer Al Lawati Join Date: Feb 2011 Posts: 1 Rep Power: 0	Hi everybody, I am a Bachelor student working on a problem using ANSYS Flotran (GUI) , which I am new in, to find the velocity and temperature distribution of air due to buoyancy effect under constant heat flux. The analysis is for a simple 2D square model with the flux at one side and all other sides are at room temperature. I have solved the problem using TDMA solver for pressure and temperature, for heat flux of 70 W/m2, and it worked properly. But when I solved it for heat flux of 70000 W/m2, the solution didn't converge and the program gave me this error message: "Negative or zero temperatures may be avoided by either mesh refinement or modified inertial relaxation especially if Petrov-Galerkin formulation is used for the energy equation (FLDA,ENRG,SUPG,T)." I tried to refine the mesh and change the relaxation factors but no use. Can anybody help me to choose the appropriate solver for this problem with this high flux. Also if you have any other suggestions to converge the problem I appreciate knowing them. Please reply soon.

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February 6, 2011, 06:04		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	Flotran died out long ago. Time to upgrade to a modern CFD solver. Your university probably has licenses of CFX or Fluent, so change to one of them.