invalid wall function specifications
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Hello everyone,
I made a small geometry in salome. (figure attached below). In this geometry, I made three groups (inlet, outlet and sideWalls). And then I meshed this geometry in Salome and imported as a UNV file in Openfoam. But when I model a kEpsilon Turbulence model through this region, It gives me the following error: Code:
--> FOAM FATAL ERROR: But I don't know, that is it right to do like this manually OR is it possible to group the sideWalls as a wall type in salome itself? because my solver is not converging after doing this and the values of k and Epsilon are going very very high. But I don't know the error is because of this patch type that I changed to wall manually OR I am making some mistake in modelling the Turbulent flow? Can someone please help me out in this. I shall ve very thankful to you. Thank you |
Hi,
Just edit the file constant/polyMesh/boundary and for the relevant patches change the type to wall. Regards, Tom |
Quote:
Thank you so much for your helpful response. it worked. Thank you I have one more question here, what is the time step continuity error and what could be the possible reasons for it? I am running my simulation but it stops after some iterations with the following error: Code:
--> FOAM FATAL ERROR: And when I see the log file, the time step continuity error is very high, as you can see below: Code:
Time = 0.1 I am not able to understand what is the problem? and this problem only comes when I change the fluid flow from laminar to Turbulent. Any help would be highly appreciated. Thank you |
Hi,
Time step continuity error is the mass unbalance after your iteration/time step, which is known after the pressure equation is solved. It should be much lower than 1. There are many posts already on this forum about it. Your problem is with the heat enthalpy equation: Code:
DILUPBiCG: Solving for h, Initial residual = 1, Final residual = 0.04574217, No Iterations 2 Please check this thread. |
Thank you for your reply.
I try to explain my problem. I am using chtMultiRegionSimpleFoam. My Openfoam version is 4.1. I made my geometry in salome, and then imported to OpenFoam as a UNV file. I have multiple regions in my geometry, (heaters, box, and fluid). Both heaters and fluid are in the box. Now, I want to simulate the turbulent flow in the fluid region. I am using kEpsilon Model. I am trying to model incompressible flow. I put boundary conditions for alphat, k, epsilon, nut etc in system/fluid/changeDictionaryDict file. This file is shown below: Code:
boundary Now, I have the following doubts: 1. How and where actually we define that out flow would be incompressible? 2. As you can see in the file above, in the alphat portion, for the boundary fluid_to_box, I have put the wall function. before it was compressible written before the wall function, but I removed it because I am trying to simulate incompressible. But it gave error that: Code:
--> FOAM FATAL IO ERROR: 4. Can I use other boundary conditions, other than wallfunctions on this boundary fluid_to_box(mappedwall)? I tried to explain my problem, but if you need any other information, I would be happy to give. Thank you |
Hi,
Answer to questions 1-3: Your solver is compressible. I am not sure you can use an incompressible thermophysical model in version 4.1, but that may be the way to go. As far as I know you can only use the compressible:: version with that solver and OpenFOAM version. Not even sure if there is an incompressible variant in version 4.1. 4. You could use calculated, but that would require a resolution in your mesh that allows to fully resolve the (thermal) boundary layer (y⁺~1). As you have not provided any information about the mesh (checkMesh output, mesh type, yplus) you are using I do not know if that is the case. Also I now noticed you are asking questions in multiple topics about the same problem, so I think that you are going to get different answers and it will be difficult to get a clear picture. Furthermore other users will have problems getting a clear answer, this is not the best way forward. Regards, Tom |
Hi,
Thank you so much for your reply. I got to know that I will use compressible flow in my simulation, and then I changed my thermophysical properties accordingly. and I am using wall function Now. But, when I RUN the solver, after 3 4 iterations, the solver stops and the temperature of the fluid suddenly becomes very high. When I change the rhomax and rhomin in my system/fluid/fvSolutions, then it runs a little bit longer and again stops saying "maximum number of iterations exceeded". Actually before, I was using rhomax and rhomin equals to 1000, because I was using constant density of 1000 in thermoPhysicalProperties. But now, I am using icoPolynomial for density, so I don't exactly know that what values to set for rhomax and rhomin? I don't know exactly what information do you need to answer this question, but I tried, please let me know if you need any further information. Thank you And related to asking questions in many topics, I am sorry for that, I'll take care of it. Thank you once again. |
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