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Hello guys,

I'm having some problems trying to work on a quite simple model, that you can see attached. 3 of the walls (half tube, and the 2 pieces of carter) have 3 different temperatures and there is air in the middle. I would like to know the exchange of energy between the 3 elements due to convection and I'm using a stationary solver. The strange thing is that I was able to have a solution for a lot of initial conditions but sometimes, changing the temperature, the model doesn't work anymore giving the following error: Undefined value found in the equation residual vector. There are 260 degrees of freedom giving NaN/Inf in the vector for the variable comp1.T. at coordinates: (0.11073,-0.054257), (0.110392,-0.0503973), (0.110246,-0.0612593), (0.110176,-0.0575849), (0.109958,-0.053865), ... There are 447 degrees of freedom giving NaN/Inf in the vector for the variable comp1.u. at coordinates: (0,-0.062), (-5.08159e-020,-0.0612062), (-1.11795e-019,-0.0602536), (0.00382759,-0.062), (0.11073,-0.054257), ... There are 447 degrees of freedom giving NaN/Inf in the vector for the variable comp1.v. at coordinates: (0,-0.062), (-5.08159e-020,-0.0612062), (-1.11795e-019,-0.0602536), (0.00382759,-0.062), (0.11073,-0.054257), ...

. How could I solve a problem like this?

ps: for this type of study is better to use the gravity or to define a gravity force?ps: for this type of study is better to use the gravity or to define a gravity force?