[lin]

The partial code of buoyantBoussinesqPimpleFoam is as follows:

while (pimple.loop())
{
#include "UEqn.H"
#include "TEqn.H"

// --- Pressure corrector loop
while (pimple.correct())
{
#include "pEqn.H"
}


At first the Ueqn is solved, the predicted velocity field is calculated. I think the Teqn should be placed after the pEqn is solved, when the real divergence free veolcity field calculation is finished, as the velocity field is used by the Teqn. This strategy is used in the wiki example:
http://openfoamwiki.net/index.php/Ho...ure_to_icoFoam

Can any expert explain for me why TEqn is placed before the pEqn?

[fabian_roesler]

Hi

I'd say this depends on the point of view. When TEqn is solved after the momentum predictor step and before the pressure corrector loop, the old velocity field is used to solve for temperature. Hence, energy/temperature is the first quantity which is solved for and all temperature dependent thermophysical properties can be calculated and used in the pressure corrector loop. Solving for temperature after the pressure corrector would mean that all thermophysical properties depend on the old temperature field. This would be especially disadvantageous when it comes to free convection flows.
One way or the other, we have a sequential method for solving the system of equations and one will always depend on old values. Please correct me if I am wrong.

Cheers

Fabian

[lin]

Thanks Fabian for your reply.
I think it is more reasonable to place Teqn after peqn. For the current strategy, placing Teqn before peqn, the additional terms in the predictor and corrector step are not consistent, as their values changes by the Teqn. Is this also advantageous?