dpdt-term in energy equation of buoyantPimpleFoam
Hello all,
I am simulating a buoyancy-driven flowcase with large temperature gradients using the buoyantPimpleFoam solver in OF2.3. The fluid (water) is between 15C and 285C and its thermophysical properties are set using polynoms to have them vary with temperature: Code:
/*--------------------------------*- C++ -*----------------------------------*\ Since the equationOfState is set as icoPolynomial, this means we will have no compressibility in the fluid, which is fine since it is water we're dealing with here. However, simulating this WITHOUT the flag "dpdt off;" as seen above, leads to divergence almost for all cases I've tried. Simulating WITH the flag "dpdt off;" gives good results, and I'm happy with using that. My question is: where does this dpdt term come from? If we take a look at the source code for solving the energy equation in the buoyantPimpleFoam solver: Code:
{ Any input on this matter, or the general apporoach of this problem, is appreciated. // Jens |
dpdt is a field defined in createFields.H of the solver.
Code:
Info<< "Creating field dpdt\n" << endl; Code:
if (thermo.dpdt()) |
Thank you for your reply Joachim.
Yes, I understand how the dpdt term is implemented in the code, but I guess this question is more about how theory is implemented in OpenFOAM. So to clarify, why does buoyantPimpleFoam have the dpdt term in the energy equation AT ALL? Again, I could be looking in the wrong places, but I simply can't find it in any books on fluid dynamics. |
E.g. the derivation of the (total) enthalpy equation (equation 2.27) in Versteeg et Malalasekera, An Introduction to Computational Fluid Dynamics - The Finite Volume Method (2nd edition) or equation 1.86 in the Theory Manual of CFX.
Or here: http://www.cfd-online.com/Forums/ope...-enthalpy.html |
Ah, thank you. Now i feel stupid, I was looking at the completely wrong equation. That is exactly what I needed to know, thanks!
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