Continuity errrors deltaT

dominic · November 20, 2014, 09:57

Hello folks,

Why is there a deltaT multiplied with div(phi) to compute the continuity errors in continuityerrs.H ?

Shouldn't there be just div(phi) ?

Dominic

dominic · November 25, 2014, 22:11

I'm posting this again. Pardon me if this question is trivial.

Why is there a deltaT multiplied with div(phi) ?. As the name goes- time step continuity errors, how significant is this compared to the case without multiplying deltaT. ?

Excerpt from continuityErrs.H:

volScalarField contErr(fvc::div(phi));

scalar sumLocalContErr = runTime.deltaTValue()*
mag(contErr)().weightedAverage(mesh.V()).value();

scalar globalContErr = runTime.deltaTValue()*
contErr.weightedAverage(mesh.V()).value();
cumulativeContErr += globalContErr;

Info<< "time step continuity errors : sum local = " << sumLocalContErr
<< ", global = " << globalContErr
<< ", cumulative = " << cumulativeContErr
<< endl;

November 20, 2014, 09:57	Continuity errrors deltaT	#1
dominic Member Dominic Chandar Join Date: Mar 2009 Location: United Kingdom Posts: 31 Rep Power: 17	Hello folks, Why is there a deltaT multiplied with div(phi) to compute the continuity errors in continuityerrs.H ? Shouldn't there be just div(phi) ? Dominic

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November 25, 2014, 22:11		#2
dominic Member Dominic Chandar Join Date: Mar 2009 Location: United Kingdom Posts: 31 Rep Power: 17	I'm posting this again. Pardon me if this question is trivial. Why is there a deltaT multiplied with div(phi) ?. As the name goes- time step continuity errors, how significant is this compared to the case without multiplying deltaT. ? Excerpt from continuityErrs.H: volScalarField contErr(fvc::div(phi)); scalar sumLocalContErr = runTime.deltaTValue()* mag(contErr)().weightedAverage(mesh.V()).value(); scalar globalContErr = runTime.deltaTValue()* contErr.weightedAverage(mesh.V()).value(); cumulativeContErr += globalContErr; Info<< "time step continuity errors : sum local = " << sumLocalContErr << ", global = " << globalContErr << ", cumulative = " << cumulativeContErr << endl;