Ansys Learning Forum Forums Discuss Simulation Fluids Oil and water-vapour mixing at supercritical conditions Reply To: Oil and water-vapour mixing at supercritical conditions

mhchoudary
Subscriber

I have tried both: using PR-EOS for Oil and providing manually properties for Oil. The properties which i provide manually are correct.

However, water-vapour is assigned Peng-Robinson. The properties are for individual components are corerct.

The problem is, i think, in the mixture. When i use 'Volume-weighted-mixing' in mixture-templete, the solution converges.

However, as soon as I use PR or any other real gas model in mixture-template, residulas especially "continuity" blow up after say 1500 iteration (depending on the timestep). It looks like that as soon as supercritical water enters into the reactor and mix with the Oil, simulation starts diverging.

I am intializing reactor half filled with supercritical water and half filled with Oil. Supercritical water inlet is at bottom-half which is filled with oil. 

While diverging i get many kind of errors/warnings: Usually it starts with "turbulent viscosity limited to viscosity ratio of 1.000000e+05" and then "reverse flow occured in xx faces of oulet", and "temperature is below the spinodal point in xx cells on zone x". 

I have tried everything, from decreasing time step to increasing mesh size etc. but nothing has worked so far. Any help or hint how to get rid of this issue is much appreciated.

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