[tangd]

Hello,

I ran my case with both OpenFoam (sonicTurbFoam) and CFX5 and compared
results by generating graphs of temperature, pressure, mass and mass flow rate
as well as some contour screenshots (see attached images). In principle,
the axisymmetric-2D-system is a simple volume with an inlet. For OpenFoam
a 5° sector was used with wedges.

I found that temperature and pressure of OpenFoam are lower than the corresponding
results of CFX-5. Additionally, in OpenFoam the overall mass in the closed volume
is lower than the integral value of the inlet mass flow rate. Thus, it looks as if
mass is lost during the calculation. Note, the massflow input (and also the
total temperature) at inlet is nearly the same as in CFX5. The mesh was the same,
of course.

I have checked a lot of things: turbulence model, boundary conditions, thermal
properties, etc, but haven't found the reason why in OpenForm the mass balance (and
consequently the energy balance) is not fulfilled. The schemes I used are:

================================================== ============================
ddtSchemes
{
default CrankNicholson 0.5;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss limitedLinearV 1;
div(phi,k) Gauss upwind;
div(phi,epsilon) Gauss upwind;
div(phi,R) Gauss upwind;
div(R) Gauss linear;
div(phid,p) Gauss limitedLinear 1;
div(phiU,p) Gauss limitedLinear 1;
div(phi,h) Gauss limitedLinear 1;
div((muEff*dev2(grad(U).T()))) Gauss linear;
}

laplacianSchemes
{
default none;
laplacian(muEff,U) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DREff,R) Gauss linear corrected;
laplacian(DepsilonEff,epsilon) Gauss linear corrected;
laplacian((rho*1|A(U)),p) Gauss linear corrected;
laplacian(alphaEff,h) Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p;
}
================================================== ============================

I've also used Euler time discretisation, but nothing changed. So far, I didn't
change the spatial discretisation, it's still the default setting from prism.
The solution settings are:

================================================== ============================
solvers
{
p BICCG 1e-12 0;
rho ICCG 1e-12 0;
U BICCG 1e-12 0;
h BICCG 1e-12 0;
k BICCG 1e-12 0;
epsilon BICCG 1e-12 0;
R BICCG 1e-12 0;
}

PISO
{
momentumPredictor yes;
nCorrectors 2;
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}
================================================== ============================

Thus, does anybody have an idea where the problem could be? The unconserevd
energy and mass balance make me uncomfortable ;-(