# SIMPLE loop in interTrackFoam

 Register Blogs Members List Search Today's Posts Mark Forums Read

 March 11, 2009, 05:12 Hello, I have a question c #1 Member   Virginie Ehrlacher Join Date: Mar 2009 Posts: 52 Rep Power: 10 Sponsored Links Hello, I have a question concerning the SIMPLE loop in interTrackFoam, especially about the velocity equation. In interTrackFoam, UEqn is implemented this way: tmp UEqn ( fvm::ddt(rho, U) + fvm::div(phiNet, U) - fvm::laplacian(mu, U) ); UEqn().relax(); solve(UEqn() == - fvc::grad(p)); whereas in other solvers using the SIMPLE algorithm, it is implemented this way: tmp UEqn ( fvm::ddt(U) +fvm::div(phi,U) -fvm::laplacian(nu,U) ); UEqn.relax(); solve (UEqn == -fvc::grad(p)); I understand that the difference is that the interTrackFoam equation is the second one multiplied by rho, but in that case, should the second term -fvc::grad(p) not be multiplied by rho as well? so that the equation should become something like: tmp UEqn ( fvm::ddt(rho, U) + fvm::div(phiNet, U) - fvm::laplacian(mu, U) ); UEqn().relax(); solve(UEqn() == - rho()*fvc::grad(p)); or something like that? If what I said is wrong, is there something that I misunderstood in the equation solving in OpenFOAM? Otherwise, how should I write the equivalent of the line solve(UEqn() == - rho()*fvc::grad(p)); ? Thank you in advance

 March 11, 2009, 05:23 Hi Virginie If you look at #2 Senior Member   Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Deltares, Delft, The Netherlands Posts: 1,749 Rep Power: 29 Hi Virginie If you look at 0/p in the hydroFoil test case, then you will see that the pressure has dimensions which differ from those in for instance simpleFoam-tutorials. Thus rho is incorporated in p. I hope it did clarify you doubts. Best regards, Niels __________________ Please note that I do not use the Friend-feature, so do not be offended, if I do not accept a request.

 March 17, 2009, 06:38 #3 Member   Virginie Ehrlacher Join Date: Mar 2009 Posts: 52 Rep Power: 10 Thank you Niels. Indeed, I had not pointed out that the p dimensions was different. Thank you for your answer, it helped a lot! Virginie

 March 17, 2009, 06:40 #4 Member   Virginie Ehrlacher Join Date: Mar 2009 Posts: 52 Rep Power: 10 Hi, just a quick message to say that I resolved my problems. This high pressure is not a divergence, it is the real result. My problems come from the fact that the cells of my mesh become very flat. Virginie

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post rajon OpenFOAM Running, Solving & CFD 30 January 1, 2016 17:27 virginie_e OpenFOAM Running, Solving & CFD 2 November 8, 2011 12:52 virginie_e OpenFOAM Running, Solving & CFD 8 March 4, 2009 06:07 kester OpenFOAM Running, Solving & CFD 10 November 8, 2007 03:55 Sinan FLUENT 0 January 18, 2005 19:04