rho and rhoFinal in fvSolution and others

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 July 9, 2019, 21:39 #2 Senior Member   Ruiyan Chen Join Date: Jul 2016 Location: Hangzhou, China Posts: 162 Rep Power: 9 This signals divergence. "rho max/min" indicates the maximum and minimum density in the field. OpenFOAM uses these to allow you to check the calculations. Obviously, if the density at some spots goes to 0, it's no good. Normally this shouldn't happen though, for example if you are using the ideal gas law, 0 density corresponds to infinite temperature (rho = p/RT). Therefore, this clearly suggests that your calculation is diverging. Check your boundary conditions first, then think about the numerics. I'm not sure about the transonic options, but you should have nOuterCorrectors set to some number (in the PIMPLE entry) instead of nothing. Typically it should be around 5~100. PCG should be a good linear solver, I don't think it is causing problems. About the "diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0" line, you can search the forum for more details, or take a look at some textbooks for numerical methods. It has something to do with the fact that the coefficient matrix for calculating density has only diagonal terms, and obviously you don't need to do any iterations to solve it.

 July 10, 2019, 04:27 #3 Senior Member   LT Join Date: Dec 2010 Posts: 104 Rep Power: 15 cryabroad, thanks! Now it's very clear this exception occurs due to the density. I follow one tutorial case to define the fixed wall and the nozzle exit zone of the liquid fuel supersonicFreestream instead of fixedValue (0 0 0). It's my first time to do supersonic calculation, I am not sure this boundary condition is right.

 July 15, 2019, 09:36 #4 Senior Member   Carlo_P Join Date: May 2019 Location: Italy Posts: 176 Rep Power: 7 Hey, if you can use at least 2 as value for correctors: nCorrectors 2; nNonOrthogonalCorrectors 2; for this particolar problem, use also a very small relaxator factor for rho, for exampple 0.1 can be correct. Furthemore, use the term bouded in the FvSchemes. Least, use mu=0 in trasportProperties. It is not correct, but help you to find a solution. Not a correct solution, but next to the correct one.

 Tags coupled, openfoam, sprayfoam, supersonic