[chew]

which there are hot fluid flow in surrounded cold fluid flow.
steady state and incompressible fluid.
so I think that I need to fix convection coefficient, (wall conduction coefficient, wall thickness), heat capacity for two species.

what is proper solver for me?

in openFoam homepage, i can find 'buoyantBoussinesqSimpleFoam' but I don't know how to put heat capacity or convection coefficient because there is not thermodynamic properties file. how can I do?

also heat exchange solver give a solution only a species. It means that I have to change solver for two species? or is there another easy way?
i need your hint

[wyldckat]

Quick answer: The solvers you're looking for are the ones named chtMultiRegion*Foam. OpenFOAM has a lot of tutorials for it and there is a simplified/incomplete training tutorial provided here: http://openfoamwiki.net/index.php/Ge..._-_planeWall2D

[chew]

your answer is useful for me, but chtMulti...foam is for compressible fluid but i need incompressible's one so I tried to mix buoyanstB...Simplefoam and that.