# InterFoam with lid driven cavity

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 July 10, 2005, 21:50 I tried to produce a lid drive #1 Senior Member   Billy Join Date: Mar 2009 Posts: 167 Rep Power: 9 I tried to produce a lid driven cavity flow using interFoam. I set initial values of gamma in some cells to 1.0 and the rest to 0.0. I wanted to simulate a mixing of two fluids, however I get always the same message even using smaller time steps: ... Reading transportProperties Selecting incompressible transport model Newtonian Selecting incompressible transport model Newtonian Calculating field g.h time step continuity errors : sum local = 0, global = 0, cumulative = 0 Starting time loop Max Courant Number = -0 Time = 0.001 Liquid phase volume fraction = 0 Min(gamma) = 0 Max(gamma) = 0 Liquid phase volume fraction = 0 Min(gamma) = 0 Max(gamma) = 0 Liquid phase volume fraction = 0 Min(gamma) = 0 Max(gamma) = 0 Liquid phase volume fraction = 0 Min(gamma) = 0 Max(gamma) = 0 time step continuity errors : sum local = nan, global = nan, cumulative = nan ExecutionTime = 0.12 s ... Does anyone know what might be wrong?

 July 10, 2005, 22:22 Actually the error looks like #2 Senior Member   Billy Join Date: Mar 2009 Posts: 167 Rep Power: 9 Actually the error looks like this: ... Max Courant Number = -0 deltaT = 0.001 Time = 0.001 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 time step continuity errors : sum local = nan, global = nan, cumulative = nan ExecutionTime = 0.1 s Max Courant Number = -0 deltaT = 0.001 Time = 0.002 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 Liquid phase volume fraction = 0.0625 Min(gamma) = 0 Max(gamma) = 1 time step continuity errors : sum local = nan, global = nan, cumulative = nan ExecutionTime = 0.22 s ...

 July 11, 2005, 06:40 You seem to get a division by #3 Super Moderator   Mattijs Janssens Join Date: Mar 2009 Posts: 1,416 Rep Power: 17 You seem to get a division by 0. Also you have no flow? Nothing is solved for it seems? Do you have valid boundary conditions? Valid initial conditions? If you are interested in where it goes wrong: set the environment variable FOAM_SIGFPE to 1 which will make the code coredump and then look at the core in a debugger.

 July 11, 2005, 14:37 I don't know what happened, bu #4 Senior Member   Billy Join Date: Mar 2009 Posts: 167 Rep Power: 9 I don't know what happened, but I know it was due to the mesh file. I created one using blockMesh and it worked OK. The original mesh file seemed OK when viewing it in paraview though. Does OpenFOAM automatically orient the face normals?

 July 11, 2005, 17:50 Yes, all boundary faces point #5 Super Moderator   Mattijs Janssens Join Date: Mar 2009 Posts: 1,416 Rep Power: 17 Yes, all boundary faces point away from the owner cell. There is a section in the user guide about the mesh structure.

 July 13, 2005, 15:05 Hi, After I got this case w #6 Senior Member   Billy Join Date: Mar 2009 Posts: 167 Rep Power: 9 Hi, After I got this case working (Lid-driven cavity flow with two phases) I noticed that altering the surface tension produces little effect on the output. I tried positive, negative and zero values of the surface tension and there seems to be no mix between the two fluids. Also, both fluids have same material properties such as density and viscosity. I assume that: A postive surface tension -> immiscible A negative surface tension -> miscible Is this right? PS: I wish to thank the OpenFOAM team for making available such a great software.

 July 13, 2005, 15:44 interFoam uses a VOF-type meth #7 Senior Member   Join Date: Mar 2009 Posts: 854 Rep Power: 14 interFoam uses a VOF-type method to capture the interface which of course does not allow mixing of the phases, that is the point. Negative surface tension has no physical meaning and may very well destabilise the solution algorithm.

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