difficulty in setting up DPM model
 

I'm trying to simulate evaporating mist flow in rectangular channel heat sink.

I have enabled energy, species transport and DPM in models. I have to treat air+water vapor as one phase and droplets as other. I have set up surface type of injection at inlet.

Initially I have entered no of continuous phase per discrete phase as 0 and then solved it until convergence is reached. Then I go again and changed it to 40 and set convergence criteria to none. After solving it for few iterations, I'm not getting expected results. Am I solving DPM model correctly or not?

It is my first question on this forum, so if you need any more info please let me know. Any help would be very grateful. Thanks.

Helllo!
I am working on the same two models. Were you able to solve your problem?

It's late to answer OP, but...

Such a statement is useless unless you
1. Tell us which results you received, and
2. Tell us which results you expected.

Hi pakk,

First of all, you have helped me a lot during the problems I faced. And I'm really grateful.

I'm trying to model a scenario where particle movement happens via diffusion and also there are particle interactions with the channel wall.

So, I should use both DPM and Species transport models, shouldn't I?
My questions are,
1. Can I use both models in one simulation?
if yes, I can put the UDF for interactions via DPM model, and the species transport model will take care of diffusion flux.

2. if no, should I use DPM model and extend the UDF with DEFINE_DPM_HEAT_MASS macro to get diffusion flux

3. Or, can I include a body force on diffusion particles via the species model? Can I use DPM_BODY_FORCE macro in the species model

Looking forward to your reply.
Thank you!

Hi Pakk,

Can you please help me with this.
Tell me about your opinion.
Thanks!

If you talk about diffusion, things are macroscopic. You don't model individual trajectories, but you model a particle density, approximating it as a continuous gas.

But when you say particle-wall interactions, it is microscopic.

You have to choose which one you want.
-macroscopic: use diffusion equation, and find a model for the boundary condition on the wall. I don't know how to go from particle-wall interaction to particle-density-boundary equation.
-microscopic: use DPM trajectories everywhere. Use brownian forces to get the effect of diffusion. Concept is not so hard, but this can be very slow to compute...

Thank you so much Pakk.
I'll move forward with your suggestions.