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Flotran natural convection tips
  Key things to consider when setting up your model:
  • Enable variable density with FLDATA, VARY, DENS, T
  • Define an acceleration body force with ACEL
  • Set PRES = 0 at lower inlet; leave upper outlets unspecified since overall delta-P driven by buoyancy effects is unknown
  • Use SUPG advection scheme for momentum equations with FLDA, ADVM, MOME, SUPG
  • Use SUPG advection scheme for energy equation with FLDA, ADVM, TEMP, SUPG
  • Use PCG solver for PRES with FLDA, METH, PRES, 3
  • Tighten convergence tolerance on PRES with FLDA, CONV, PRES, 1.0E-15
  • Use PGMR solver for TEMP with FLDA, METH, TEMP, 4
  • Tighten convergence tolerance on TEMP with FLDA, CONV, TEMP, 1.0E-20
  • Consider running the simulation as a transient if convergence difficulties are encountered
If heat generation rates are known, use BFE, BFA, BFV, etc., to impose this load. If you plan to solve a thermal/electric/CFD coupled field problem:
  • Use heat generation rates from thermal/electric solution as loads in a CFD conjugate heat transfer solution
  • Use CFD-computed convective heat fluxes on outer surfaces of coils as loads to the next thermal/electric solution
  • Iterate between the two solutions until the two computed temperature distributions match
  Posted by Mark Troscinski (ANSYS, Inc.) on 07.14.2002