[AC148]

Hi everyone,

I'm french so sorry for my bad english. I encountered some difficulties with multiRegionSimpleFoam. I want to simulate an heat exchange from a fluid to an other fluid with a solid part between them. My configuration is make up with 3 coaxial cylinders; all the parts are initialy at 300K. On the internal cylinder there is a fluid inlet at 500K and in the external cylinder the fluid inlet is at 300K. The two fluids flow in opposite direction.

I expected that the first flow transfer his heat to the solid wich will transfer it to the second fluid, but the fluid of the internal cylinder become colder too quickly like if the temperature at inlet was not correctly set. I try to use the same BC on an other geometry which is simple and the fluid transport the temperature correctly.

I tried to simulate the same thing on starccm+ with similare boundary conditions, it works and i don't understand why OpenFoam could not find the same results.

Here is the boundary i used for the internal fluid, the flow is correct when i visualize it on paraview, only the temperature is not correct :

 boundary
{
    fluidint_to_solid
    {
    type mappedWall;
    sampleMode      nearestPatchFace;
    sampleRegion    solid;
    samplePatch     solid_to_fluidint;
    }
 
}


U
{
    internalField   uniform (0 0 -0.1);
    boundaryField
    {
       maxZ_fluidint
        {
           type            fixedValue;
            value           uniform (0 0 -0.1);
        }
          minZ_fluidint
        {
              //type            zeroGradient;
                 type            inletOutlet;
            inletValue      uniform (0 0 0);
            value           uniform (0 0 -0.1);
        }  
            fluidint_to_solid
        {
            type             fixedValue;
            value           uniform (0 0 0);
        } 
    }
}

T
{
    internalField   uniform 300;
    boundaryField
    {
       maxZ_fluidint
        {

           type            fixedValue;
           value           uniform 500;
        }
          minZ_fluidint
        {
            type            zeroGradient;
        }  
            fluidint_to_solid
        {
            type            compressible::turbulentTemperatureCoupledBaffleMixed;
            Tnbr            T;
            kappaMethod     fluidThermo;
            value           uniform 300;
        }     
    }
}

/*epsilon
{
    internalField   uniform 0.01;
    boundaryField
    {
        ".*"
        {
            type            epsilonWallFunction;
            value           uniform 0.01;
        }
    }
}

k
{
    internalField   uniform 0.1;
    boundaryField
    {
        ".*"
        {
            type            kqRWallFunction;
            value           uniform 0.1;
        }
    }
}*/

p_rgh
{
    internalField   uniform 1e5;
    boundaryField
    {     
       maxZ_fluidint
        {
           // type            zeroGradient;
             type            fixedFluxPressure;
            value           uniform 1e5;
        }
          minZ_fluidint
        {
            type            fixedValue;
            value           uniform 1e5;          
        }  
        
            fluidint_to_solid
        {
           // type           zeroGradient;
             type            fixedFluxPressure;
            value           uniform 1e5;
        } 
    }
}

p
{
    internalField   uniform 1e5;
    boundaryField
    {
       maxZ_fluidint
        {
        type            calculated;
            value           uniform 1e5;
        }
          minZ_fluidint
        {
             type            calculated;
            value           uniform 1e5;
        }  
  
            fluidint_to_solid
        {
         type            calculated;
            value           uniform 1e5;
        } 

    }
}

Could you help me find why the result of the simulation is wrong and help me identify the reason of this wrong result ? I try a lot of different boundaries conditions without success.Thanks for your help.

[laurentD]

Hi.
i am french too so i understand perfectly your english language.
The last time i faced tis problem, the bad unity was used for the mesh, (meters for millimeters for example).
i think you might take a look on the polymesh/points file.
If there is nothing strange there, maybe you should show us the files you use to initialize the velocity, the temperature, the pression... (under 0/)
Have a good day,

[AC148]

Thanks for having answered quickly, it seems the mesh is good and the dimensions are correct, when i run checkmesh the mesh is okay too.

I have attached all the boundaries file in 0. In my case, i have none radiation model and i set turbulence to laminar. If it's necessary i can upload all the case.

I create the mesh with Salome, and export it as unv file to convert it to OpenFoam. I have no error when i run the simulation and i used water for fluid and aluminium for the solid.

Do you see something wrong in my boundaries, i used mappedWall to link boundaries between domains.

I attached the constant file too.

0.zip

constant.zip

[AC148]

Nobody has an idea ?