- **OpenFOAM Running, Solving & CFD**
(*https://www.cfd-online.com/Forums/openfoam-solving/*)

- - **To solve my own equation**
(*https://www.cfd-online.com/Forums/openfoam-solving/59760-solve-my-own-equation.html*)

Hi Rafal,
As you said to meHi 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 |

Hi Lam,
there can be many cHi 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 |

Thamks Rafal to reply me,
IThamks Rafal to reply me,
I'm thinkin about your ideas. Regards, Lam |

Hi world!
I did a big mistaHi world!
I did a big mistake, I delete by accident my doc/Doxygen/html!! How can I get it again??? Thanks in advance, Lam |

you can untar OF project in OTyou 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 |

Oki, Rafal!
You're right!
Oki, Rafal!
You're right! Thanks a lot! Lam |

Hi world,
I'm wondering mysHi 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 |

HEY, everyone!
Nobody can gHEY, everyone!
Nobody can give me some advice? Cheers, LAm |

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