I'm try to resolve a buoyancy driven problem. The domain consist of a fluid volume, inside witch is positioned an alluminium box. Inside the alluminium box there are some hot solid parts. I model this solid heat sources with sorent.f. I cannot reach convergence for solid and density residual! Can someone helps me!?! thank you regards

Dear Scribor,

In the User guide of STAR-CD find the word convergence. It will go to the default values of relaxation factors for the variables. For the PISO algorithm there are some guides how to avoid these problems (these guides are the same for SIMPLE and SIMPISO). I think the first think you can do is to reduce the relaxation factor for velocities in decrements of 0.05.

Regards George

copy form star_uguide v3.26 P6-19

It is usually advisable to run conjugate heat transfer simulations in double precision. This helps to overcome potential convergence problems arising as a result of a large disparity in thermal conductivity between fluid and solid. The choice of single or double precision mode can be made when running STAR (see Chapter 2, "Running a CFD Analysis", Step 6).