Fluids mixture approach

Questions and remarks about code_saturne usage
Forum rules
Please read the forum usage recommendations before posting.
Post Reply
samarul
Posts: 2
Joined: Mon Oct 24, 2022 2:31 pm

Fluids mixture approach

Post by samarul »

Hello to you all!

I am just starting to use Code_Saturne (did some tutorials). My goal for the moment is to simulate the flow for two pipes (they join in one) with two fluids (different density and temperature). I created two meshes that I will join but I am lost as how to specify the different density for the initial mesh (in inlets I can add velocity and temperature).

Can you please guide me - documentation or an example?

Thank you!
Antech
Posts: 197
Joined: Wed Jun 10, 2015 10:02 am

Re: Fluids mixture approach

Post by Antech »

I think you can use 2 species. Open Species Transport under Calculation Features and add 2 species. Also, you need to add temperature scalar in Thermal Model window. You will have species concentrations (I don't know mass or volumetric) and temperature at any inlet. Then, to account for thermophysical properties effect, set Density, Viscosity e.t.c. in Volume Conditions => all_cells dialog to "User law", then give expressions for thermophysical properties that depend on species concentrations (please check if Saturne operates with mass or volumetric fractions).
I never used this approach but it should work. Saturne developers will clarify if there are some additional things to pay attention for.
samarul
Posts: 2
Joined: Mon Oct 24, 2022 2:31 pm

Re: Fluids mixture approach

Post by samarul »

Thank you for your answer. Your approach seems to be the right one. I am a little bit confused about choosing two species, should it be one for each mesh? And I can not find the "User law" option in the Volume Condition for all_cells.
Antech
Posts: 197
Joined: Wed Jun 10, 2015 10:02 am

Re: Fluids mixture approach

Post by Antech »

I cannot suggest anything for multiple meshes, I never used more than one mesh with Saturne. But, actually, if you have a pipe junction, you only need one mesh for entire calculation domain. If you decide to use 2 meshes, you will need two species for both of them. Define unity concentration of the first component at one inlet and for the second component (specie) on another inlet. As if it's just one mesh.
To switch to User law, open "all cells" dialog, click "Constant" button in property group (for example, under Density) and select "user law" in dropdown list.
Post Reply