# Convectiondominated schemes

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 February 10, 2008, 13:09 Hi, All! Please, answer my #1 New Member   Dmitry Kovtunov Join Date: Mar 2009 Location: Yekaterinburg, Ural, Russia Posts: 8 Rep Power: 10 Hi, All! Please, answer my question. Is it possible to solve the convection-diffusion equation with OpenFOAM when convection is dominated?

 February 10, 2008, 13:22 Yes - in fact, it is quite eas #2 Senior Member   Hrvoje Jasak Join Date: Mar 2009 Location: London, England Posts: 1,802 Rep Power: 24 Yes - in fact, it is quite easy. __________________ Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk

 February 10, 2008, 13:58 Thanks for the answer. But cou #3 New Member   Dmitry Kovtunov Join Date: Mar 2009 Location: Yekaterinburg, Ural, Russia Posts: 8 Rep Power: 10 Thanks for the answer. But could you point to my mistake? I was doing so: solve(- fvm::laplacian(T) + (u & fvc::grad(T)) == f); where T - temperature u - predefined analytical velocity field with multiplier alpha, so u = alpha*b, where b - some vector field with div b = 0 f - source term calculated from the equation by substitution some analytical function theta satisfying boundary condition for T so when alpha is small enough (<< 1) residual = T - theta is tolerable, but when alpha is >> 1, i obtain something wrong solution which differs from theta very much. Be glad to hear any suggestions from you. Thanks.

 February 10, 2008, 16:33 Did you every look at scalarTr #4 Senior Member   Hrvoje Jasak Join Date: Mar 2009 Location: London, England Posts: 1,802 Rep Power: 24 Did you every look at scalarTransportFoam? This is where you should start from: solve ( fvm::ddt(T) + fvm::div(phi, T) - fvm::laplacian(DT, T) ); Hrv __________________ Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk

 February 10, 2008, 18:37 I've tested your suggestion. I #5 New Member   Dmitry Kovtunov Join Date: Mar 2009 Location: Yekaterinburg, Ural, Russia Posts: 8 Rep Power: 10 I've tested your suggestion. It has improved my solution but not enough. I've two problems now: 1) it is not clear how small deltaT need to be choosen to obtain stationary solution; 2) while modeling the solution become unstable on some time step i.e. after some time step an absolute residual become growing up. Any ideas? And what is the best interpolation scheme for my case? I've noticed filteredLiear to be better than limitedLinear.

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