[jtei99]

Hi! I'm new to OpenFoam and I'm trying to simulate laminar flow inside a pipe with heat transfer, using a 2D geometry. Initially I was able to simulate the flow without heat transfer using simpleFoam, but when trying to implement it into chtMultiRegionFoam even with constant temperature I get strange results. There's a zone in the wall with -5.3e4 Pa and having back flow. I've been trying different things the whole day with no results, so I'm posting here.

Here's the folder with what I have: https://drive.google.com/drive/folde...AY?usp=sharing

Photos:
https://imgur.com/a/50LZVhL

[ajithnair]

it might be your boundary conditions. Also there is only one fluid region inside the case setup. Where is the heat getting transferred to. Is here any pipe wall or solid material or another region. I could only see one region

[jtei99]

Yes there is only one fluid region. I applied the boundary condition:

wall
{
type externalWallHeatFluxTemperature;
mode coefficient;
Ta uniform 283;
h uniform 200;
kappaMethod fluidThermo;
value uniform 283;
}

I thought with that I could avoid having to define the solid around the fluid, maybe I'm wrong. But now I've borrowed the fvSchemes and fvSolution from another post and was able to get consistent results. Please tell me if I'm using the boundary condition correctly.

[piu58]

I used

p
type            zeroGradient;

U
type            fixedValue;
value           uniform (0 0 0);

p_rgh
type fixedFluxPressure;  gradient uniform 0;

T
type            fixedValue;
value           uniform 301;

kappa 	
type kqRWallFunction; value uniform 0.0; 

alphat
type            alphatJayatillekeWallFunction;
Prt             0.85;
value           uniform 0;

nut
type nutkWallFunction;   value uniform 0;