Hello everyone,
i am doing master thesis and developing cfd simulation in ansys fluent software. i am having convergence problem with my multiphase eulerian model. The liquid comes from top and leaves from bottom of cylindrical colon. the gas should enter radially from bottom side and exits from top. i gave all the boundary conditions but i am having convergence isssues. no matter what turbulance model (k omega or k epsilon) i choose, there is not any improvement. does anyone has experience with multiphase model and ready to help me?
Hi Umesh Magar ,
It is right that Eulerian gas/liquid simulations can be somewhat challenging... especially for counter-current flows as you are dealing with or if the volume fraction of the liquid phase is high.
You should try to begin by solving the gas (main phase?) flow only without the (dispersed?) liquid phase. When it is converged, you could begin to simulate the two-phase flow. Increasing the liquid flow rate gradually could be helpful. What is the global liquid volume fraction in your case?
I recommend to use the k-epsilon realizable turbulence model.
Which version of Fluent are you using?
Hello Philippe Béard ,
Thank you for response. In my case the volume fraction of liquid is around 0,0042 or 0,42%. About choosing the gas as main phase. i am not sure about that as well. I choose liquid as primary phase. does that make problem?. Are you telling me that after i get converged solution of only gas phase, i continue the same model with multiphase? Could also tell me about the phase interaction that could be more reasonable for gas/liquid flow?
I am using Fluent 2024 R1.
Thank you once again and hope to get your answer.
So, in your case, the gas is the main/continuous phase. The volume fraction of liquid is low, so you should not have convergence issues. What kind of flow are you simulating?
Solve the gas flow first with a liquid mass flow set to 0. Then, add the liquid flow and the volume fraction equation.
For the phase interaction, you can use the classical Schiller-Naumann for the drag and the ia-particle for the interfacial area.
Thank you Philippe Béard . i received converged solution now. Thanks to your advice . i used Gas as primary phase and liquid as secondary phase. like you said started increasing the mass flow of liquid from 0 to the boundary condition. i got the converged solution.
Dear Philippe Béard ,
i am currently having problem with my species-mass transfer model for Carbon capture. I have received very high value for absorption rate almost 60% higher than that of experimental data. And i notice that the value is not changing although i change the species transfer model or Herny's constant. The only thing changing the absorption rate is the value for mass inlet value for gas and the coefficient for porous medium. can you give me some tipps regarding this topic? since you have also done such works in the past.
Regards,
Umesh
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