Hello,
I am simulating flow between two containers with a pressure difference of 100Mpa. (Volumes: 1L 100Mpa and 200L 1bar) connected by a pipe of diameter 11mm. Simulation works with ideal gas, but, at 100Mpa and 50K air is no more ideal. I tried simulating with redlich kwong real gas model. Simulation works for 2-3 time steps and after that there is sudden divergence. I am unable to understand physics behind divergence. Any lead on this problem would be a great help for my simulation.
Additionally,
after initializing real gas model what should be Cp coefficients?
Regards
Naveen Shirur
At 50K, you have liquefied the O2 and N2 in the air. No gas there.
If your temperature value is a typo, then I suggest going into your RK with a density guess value based on general compressibility, Z, or Z=Pv/RT.
the temperature is very low with high pressure and also the diameter of pipe is very small the air in the system is converted to liquid
Which CFD solver you are using?
If solver is CFX you can use rgp table, it is robust for real gas simulations.
If the solver FLUENT, try with temperature ramp method i.e., first get a solution with RK EOS at higher temperature (for example 273K).
Then with this result as initial solution, obtain the solution for 50K by slowly reducing the temperature.
Since, it seems liquid phase also involves, use UDRGM which allows this phase change.
Thank you everyone for providing me leads. @chris and @Senthil Kumar, i will take your points and try. Many thanks again.
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