# To solve my own equation

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 March 23, 2007, 07:06 Hi Rafal, As you said to me #1 Member   Hoang-Lam Join Date: Mar 2009 Location: Lausanne, Switzerland Posts: 60 Rep Power: 10 Hi Rafal, As you said to me it was possible, I create my own equation in Foam. In icoFoam.C, I moved the Navier-Stokes equation for a another eqution easier: nu*Laplacien(U)=Grad(p) In th eicoFoam.C, I wrote this line below: ******************************************** fvVectorMatrix UEqn ( fvm::laplacian(nu, U) ); solve(UEqn == fvc::grad(p)); ********************************************** And I changed anything else, in any files (of course, I made the ./Allmake) But I had a wrong solution, when did: icoFoam SFOAM_RUN/tutorials/icoFoam MyCavity (MyCavity is a case that I created, diferent from the "cavity" case). My solution is actually: ************************************************ Time = 0.01 Mean and max Courant Numbers = nan nan ICCG: Solving for Ux: solution singularity ICCG: Solving for Uy: solution singularity ICCG: Solving for Uz: solution singularity ICCG: Solving for p: solution singularity time step continuity errors : sum local = nan, global = nan, cumulative = nan ICCG: Solving for p: solution singularity time step continuity errors : sum local = nan, global = nan, cumulative = nan ExecutionTime = 0.75 s ClockTime = 1 s ************************************************ I know there is somethin wrong with the timeStep here. But I do not know what and where I have to cahnge things to solve my problem! Can you, or someboby else, give me some advice? Thanks in advance, Lam

 March 23, 2007, 07:36 Hi Lam, there can be many c #2 Member   rafal zietara Join Date: Mar 2009 Location: Manchester, UK Posts: 60 Rep Power: 10 Hi Lam, there can be many causes of solution singularity. Several thing that I can see here. - you removed time derivative and you try to solve something in time(maybe start with different solver for steady state ie simpleFoam) - the equation now is diagonally equal (since diffusion term produce diagonally equal matrix; grad(p) is source term) and matrix has to be diagonally dominant to solve it. these are my quick ideas (i can be wrong) rafal

 March 23, 2007, 08:30 Thamks Rafal to reply me, I #3 Member   Hoang-Lam Join Date: Mar 2009 Location: Lausanne, Switzerland Posts: 60 Rep Power: 10 Thamks Rafal to reply me, I'm thinkin about your ideas. Regards, Lam

 March 28, 2007, 06:04 Hi world! I did a big mista #4 Member   Hoang-Lam Join Date: Mar 2009 Location: Lausanne, Switzerland Posts: 60 Rep Power: 10 Hi world! I did a big mistake, I delete by accident my doc/Doxygen/html!! How can I get it again??? Thanks in advance, Lam

 March 28, 2007, 06:21 you can untar OF project in OT #5 Member   rafal zietara Join Date: Mar 2009 Location: Manchester, UK Posts: 60 Rep Power: 10 you can untar OF project in OTHER directory than ~/OpenFOAM. and than move it to right place: i.e: \$ mkdir other \$ cd other \$ tar -xzf /path/to/OpenFoam-1.3.General.tgz #not sure of name here \$ mv other/OpenFOAM-1.3/doc/Doxygen ~/OpenFOAM/OpenFOAM-1.3/doc \$ cd .. \$ rm -rf other this should work rafal

 March 28, 2007, 09:35 Oki, Rafal! You're right! #6 Member   Hoang-Lam Join Date: Mar 2009 Location: Lausanne, Switzerland Posts: 60 Rep Power: 10 Oki, Rafal! You're right! Thanks a lot! Lam

 March 29, 2007, 07:30 Hi world, I'm wondering mys #7 Member   Hoang-Lam Join Date: Mar 2009 Location: Lausanne, Switzerland Posts: 60 Rep Power: 10 Hi world, I'm wondering myself again about simpleFoam.C I noticed that I could put the turbulence in "off": but what kind of equation will I solve as result? Somebody can help me? Thanks in advance, Lam

 March 30, 2007, 03:37 HEY, everyone! Nobody can g #8 Member   Hoang-Lam Join Date: Mar 2009 Location: Lausanne, Switzerland Posts: 60 Rep Power: 10 HEY, everyone! Nobody can give me some advice? Cheers, LAm

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