Simulation of cavitation flow:problem of heat transfer
While I solve the cavitation flow of LNG with komiga turbulence model, the RMS of HEnergy in the result kept being 1.0e+01 after only five steps(the curve of heat transfer is obviously wrong),and the rate of convergence were both zero.The details were as follows:
OUTER LOOP ITERATION = 5 CPU SECONDS = 2.227E+03   Equation  Rate  RMS Res  Max Res  Linear Solution  ++++++  UMomBulk  0.97  1.4E04  1.3E02  1.2E01 ok  VMomBulk  0.96  1.3E04  1.9E02  1.1E01 ok  WMomBulk  0.97  1.9E04  2.7E02  1.5E01 ok  PVol  0.87  1.2E05  7.4E04  5.2 9.1E02 OK ++++++  MassLNG  0.93  2.5E04  6.8E02  6.1 2.2E02 OK ++++++  HEnergyLNG 99.99  NaN  0.0E+00  0.0E+00 OK   HEnergylngs 99.99  NaN  0.0E+00  5.9 0.0E+00 OK  ++++++  KTurbKEBulk  0.96  2.8E04  4.4E02  6.0 3.1E02 OK  OTurbFreqBulk  0.95  1.2E04  4.1E02  7.7 1.9E02 OK +++++ OUTER LOOP ITERATION = 6 CPU SECONDS = 2.735E+03   Equation  Rate  RMS Res  Max Res  Linear Solution  ++++++  UMomBulk  1.22  1.7E04  1.4E02  2.8E01 ok  VMomBulk  1.24  1.7E04  2.1E02  2.8E01 ok  WMomBulk  0.97  1.9E04  2.4E02  1.1E+00 ok  PVol  8.43  1.0E04  3.8E03  5.2 9.6E02 OK ++++++ ++  ****** Notice ******   A wall has been placed at portion(s) of an OUTLET   boundary condition (at 0.3% of the faces, 0.6% of the area)   to prevent fluid from flowing into the domain.   The boundary condition name is: Blade Outlet.   The fluid name is: LNG.   If this situation persists, consider switching   to an Opening type boundary condition instead.  ++  MassLNG  8.05  2.0E03  2.6E01  6.1 5.1E03 OK ++++++  HEnergyLNG  0.00  NaN  0.0E+00  0.0E+00 OK   HEnergylngs  0.00  NaN  0.0E+00  5.9 0.0E+00 OK  ++++++  KTurbKEBulk  1.15  3.3E04  4.5E02  6.0 4.6E02 OK  OTurbFreqBulk  2.35  2.8E04  7.3E02  7.7 2.9E02 OK 
This looks like a complex model with cavitation, heat transfer and multiple phases. Have you started with a simple model and introduced the physics one bit at a time?

In fact,I have solved many cases about cavitation at different conditions. Sometimes the result I got looks very well.But for the case with different geometrics (nozzle angle),it won't work.Maybe if I change the reference state of the materials I used,it will work and I can get a result that looks reasonable .But this strategy doesn't fit any case .Do youknow the reason ? Will the reference point affect so much ? How could I avoid this wrong results with what proper settings?

Do you think explaining what you are modelling might help? And while you are at it maybe what is different about this one compared to the ones which worked well? I think that might help :)

I have compared the result with those worked well .The unique difference is that I set the simulation with different reference point .If with a actual reference point , refenthalpy and refentropy ,only some cases could work well .If with automatic refpoint ,there will be more cases that will work will .If with none, the effect will get better . However there are still some cases that can't work will. That is the problem I want to know.In different cases ,everything is same except that the geometric has different nozzle angle. Thank you for your help!

All times are GMT 4. The time now is 04:01. 