Learning Forum

[skallu20]

 Hello all, 

 

I am trying to simulate condensation on surfaces using Fluent 18.1 in 2 dimensions. I've run into a bit of a problem regarding this. I've set it up so that there is an inlet, an outlet, a condenser, and a symmetric edge, where vapor at 380 K and 5 m/s enters the control volume, and the idea is that there should be condensation on the condenser as it is 273 K. After 1000 timesteps (each 0.001 seconds), the volume report says that there is no liquid in the simulation, and in post, the contour of liquid volume fraction is completely blue, corroborating this. However, when I look at the contour for temperature, it follows a pattern which suggests that water should be condensing in a film. I am using the VOF model for multiphase, with 2 phases, the first being vapor and the second being liquid, with 1 mass transfer through evaporation condensation at default values (saturation temp of 373.15 K, etc). I have tried simulating over a longer period of time, but to similar results. Is there anything wrong with my model? How can I fix this so it makes sense? I will include a couple pictures for reference. 

[Rob]

Don't use VOF for this and update to the latest version as it's had significant improvements for this type of modelling. 

[skallu20]

Thank you so much for your reply! Should I be using the mixture model then? I tried to use that model but I was unable to input an initial velocity at the inlet. Also it seems I only have access to 18.1 through my institution.

[Amine Ben Hadj Ali]

Yes but update first. Bulk phase change at first stage might be OK but not sufficient