[prapanj]

Hi,

In simpleFoam source code, what do the following lines (in Ueqn.H) mean?

Ueqn().relax();
eqnResidual = solve
( Ueqn() == -fvc::grd(p)
).initial Residual()

I understand the part Ueqn()== -fvc::grad(p), please someone explain the rest. Thank you

[markusrehm]

Hello,

Ueqn().relax();
this is for under-relaxing the momentum equation.


Correct me if I am wrong, but I think, the two lines with "initialResidual" are for stopping the whole solution process once the residuals of all equations are low enough.

Regards, Markus.

[jploz]

Hi,

not exactly. The code

eqnResidual = solve( .. ).initial Residual()

assigns the initial residual of the equation to be solved to the existing variable 'eqnResidual' and solves the equation within a single statement.

The check, whether the convergence criterion is satisfied is done later (see file convergenceCheck.H).

HTH, Jean-Peer.