I am simulating two phase flow in pipe with CO2 as a working fluid. In the inlet I have a gas phase and in outlet I have both phases ( gas and liquid). How can I set real gas CO2 with real gas NIST in Fluent with VOF? For example: when we are modeling water in VOF, we must choose both liquid water and vapor water and set for example vapor as a phase one and liquid water as a phase two. But when we model real CO2 in two phases, there is no liquid and vapor CO2. This is true that we can choose either vapor or liquid phase but how I can choose both for two phases modeling?
Do you mean the thermal properties of CO2 or what? could you please clarify your question?
I could not understand your question. If you can be specific, may be I can help.
There is no link between VOF and material properties. What is the problem in specifying the properties in material tab?
You should be conveniently able to feed the properties.
I suggest Mixture to simulate two phase flows (in Fluent). In my view, by this approach you can eliminate the problem
Hello
What kind of flow you have a to reach a phase change of co2 , condensation , high pressure , or what ?
Then you can adjust your work for phase change from phases interaction in phases window.
The flow characteristics at the pipe inlet is supercritical but also there will be a liquid phase at the middle of the pipe but my question is : When I use NIST Real Gas, how can I set liquid and vapor phases together?
You select both phases from library , then adjust inlet condition for each phase , set mass transfer conditions between phases , set diceretization degree between phases ( recomend.= 1), fluent will solve flow problem and calculate each phase fraction along the pipe.
Thanks for your answer but there is a problem in selecting phases. When you call CO2.fld from Refprop database, you will see just CO2 and there is neither liquid nor vapor phase of CO2. As I clarified before, for water you can do it because there are both liquid and vapor water.
So , you should define the liquid phase properties and save it , and then select the gas phase,and continue as mentioned above.
So here is the problem. How you define liquid phase and gas phase of co2?
Because co2 is not in Fluent database and I have to call it from NIST. And there is just one CO2 (no liquid or vapor)
Co2 phases are exist in fluent data base.
Co2 gas phase
Co2- liq. phase
check again , as attached print screen.
The NIST real gas model assumes that the fluid you will be using in your ANSYS Fluent computation is superheated vapor, supercritical fluid, or liquid. Note that subcritical flow conditions, where vapor coexists with liquid in two-phase flow, are not supported.
I know that this may look self-referential but there is a way to simulate two-phase flows (validated for CO2 but it's a general procedure) with real fluid properties in ANSYS Fluent. It's a bit complex and it requires some coding. Good luck!
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