Learning Forum

[Rick_Sanchez]

Hi Community,

I have been trying to simulate fire suppression system liquid evaporation from nozzle for quite some time now.

For testing model my secondary phase has been water.

Also I'm not trying to simulate real evaporation but consider some small droplet size as "evaporated".

So I have set up VOF-to-DPM with adaptive mesh (3D).

Calculations have been quite unstable in the setup model sense (not convergence). There has been quite narrow parameters with timesteps/mesh where my courant no doesn't give the 250 limit error.

Nozzle has in original 8 orifices. I have simplified the model to 2 orifices by symmetry.

Initial meshing is done in Fluent.

Finally I run into Student license 512000 cell limit.

Please share your ideas on how I could modify the settings to remain within Student license boundaries. Or is it unachievable with the given model?

Is it even possible in that scale with Ansys Fluent Student 2020 R2?

This is the setup that I have come up with (attached).

S1. General.PNG

[Rick_Sanchez]

n

[Rob]

Try looking at a single hole. The Student version is intended to let you learn the concepts so now you've got the model working you may need to discuss access to a Research licence with your supervisor. n

[Rick_Sanchez]

I did try it with single nozzle as well last night.nAlso adjusted a bit some parameters:nmax sphere diameter to 0.01mmnRemoved DPM physical model options:nAnd simplified a initial mesh a bit. Still same thing.nHow can I learn the concept if I can't even simulate one nozzle?nDid the rest of the settings seemed reasonable? Maybe I have done some important mistake there which multiplies the required calculation steps more than needed.nn

[Rob]

Go into the adaption section (Domain tab?, I'm on holiday so not launching the solver to check!) and see how many refinement levels there are. I think the default is 6, which will refine (increase cell count) very quickly. Drop that to two levels. It'll not be as accurate and you may need to alter the transition settings but it should run. n

[Rick_Sanchez]

Thank you Rob. This has been the setting that I'm currently playing with at the level of 4. Will try lower values later.nHave a great holiday!n