Learning Forum

[DIWAS]

I want to convert a dpm particle just before enterning into a porous media, can it be done?

[Rob]

Yes. But you need a high enough volume fraction for VOF to work well. 

[DIWAS]

Thanks for the prompt reply, that means I need to have a very small volume near the porous surface cells. dpm particles are raindrops of diameter 3-7mm. Lets say the cell size around the surface is (0.05*0.05*0.01) and the volume of single raindrop of 3mm has volume of around 1.15e-8, then the volume fraction should alteast be around 1.15e-8/(0.05*0.05*0.01) = 4.6e-4. Is that enough? and also if I need to do it, what is the procedure. I know how to convert dpm-to-vof using water film and checked it through the contour plot for vof for phase2(water). However, I am not able to convert them directly without any surface contact. 

[Rob]

I had thought a porous jump would do it, droplet becomes film becomes VOF but looks like it wasn't set up like that. 

Taking a step back, and also noting I can't give "engineering" advice. What is the purpose of the model? Ie rain hits porous media is the model, what do you want to get out of that? 

[DIWAS]

I want to know how much rain water the porous material can hold within certain time like say 2-4 hours. I want to plot the vof in the porous medium, but I am still confused should I choose a dpm model or a mixture model?

[Rob]

Right, so a bit more complicated. 

Hold up in the porous media may not be as simple as you think - read up on porosity, permeability, wetting effects etc.  So, how you define how the liquid moves may have a very significant effect on the result. 

Given that, do you think DPM-VOF is the best approach? Or could Eulerian and the porous media Corey model better suit your needs?