I am attempting to add water through a thin pipe to a venturi that has a viscous fluid flwoing through it… I cannot establish how to allocate one fluid to one input and the other fluid to the other input… Any guidance would be gratefully received… Can’t find anything in any of the tutorials or literature about this… Thanks…
Starting at 5:25 you can see how I choose a material and assign it to the domain, that should help you!
Best,
Jousef
Thanks for that but my issue is that I have 2 inputs and want to assign a different material to each input… The only option seems to be to select the entire volume? Any idea how I do assign a different material to each input please?
Many thanks,
David.
Hi!
Can you have a look at the multiphase documentation page and let us know if this is what you have in mind?
Cheers
Hi, many thanks, yes I think so… I havenow also re-done the CAD as 2 seperate fluid channels intersecting at one point and will try with the multiphase simulation… Can’t find a multiphase tutorial (in case I can’t get it to work), do you know if one exists please?
Thanks again for your assistance,
Best,
David.
There’s an old master class video on multiphase simulations. I’ll link both the master class and the corresponding project:
You can definitely also find useful information on forums. Just to give some general pointers:
- Multiphase analysis are inherently transient, so the set up definitely requires more attention on the user’s side;
- Keep your geometry as simple as possible;
- Invest time in getting a good, coarse, optimized mesh. Hex or hex-parametric are advised. This will save you time later on;
- Have in mind that courant number is a thing for transient analysis. The best practices to estimate the initial timestep are given here.
Thank you so much, I will view and try…
Hi, I have now watched the video, and looked at the project… I am still failing to see how I can assign one fluid to one inlet and another fluid to a different inlet with a single piece geometry?? Maybe this is not possible??
Hey,
Each material corresponds to a phase fraction (1 or 0):
When setting up an inlet boundary condition, you can use phase fraction to define which fluid is entering the domain:
These pictures are from this project, if you’d like to have a look.
Cheers
Hi, sorry for late response, just wanted to say thank you so much for your help… I get in now…
Very best,
David.
When you’re assigning materials in a fluid analysis, it really matters that the material you pick has the right physical traits for the run. In different kinds of analysis, you might need density, dynamic viscosity, thermal conductivity, and also specific heat, it depends.
If the outcomes look kind of odd, like not what you’d expect, I would start by double checking whether the material properties line up with the real fluid and the operating conditions. Also, temperature can shift the viscosity and the density quite a lot, especially for thermal flows or compressible flow simulations, where small changes can snowball.
For students working through a difficult fluid analysis assignment, it’s usually more helpful to actually understand what these settings mean than to just finish fast. Some students even look up services using something like “pay someone to do my online class for me” , but having solid guidance on the core concepts can make it easier to set up future simulations the right way.