Shan chen multi-phase multi-component

Lattice Boltzmann Method LBM: Theory
#1

Hi, I am trying to simulate condensation of water in air.

I am using the shan-chen multi-phase multi-component model in order to achieve this. The goal ultimately is to study the effect of condensation in fuel cell membranes.

I am struggling a bit with some physical concepts.

Modelling water/vapour makes sense to me and I have successfully used the single-component multi-phase model to simulate condensation of water bubbles in vapour.

Taking air into consideration it becomes a bit more difficult. Basically the air contains vapour so the air is actually random gases + vapour so these are two components. The vapour itself consists of two phases vapour and liquid. Ultimately I want to show how condensation causes water droplets to form. However due to the nature of the multi-component model all I seem to get is separation of the two components (basically fluid-fluid separation). How do I within the H20 fluid distinguish between vapour and liquid?

#2

Hi ponja …

 just an idea ...   I have enever played with that..  but I have seen that some people use a MultiComponent model and introduce  different equations of state for the two fluids that the play with...  a simple gas EOS for one fluid and for the second one a VanDerWalls EOS... I'm not sure that it can be of help maybe ...

ciao
Andrea

#3

Yeah that’s a good idea. In fact that is what I am doing =) My problem still remains with how I distinguish between the two phases within the water distribution as all I have is large densities gathering at a few points and then very small density everywhere else at locations which are mostly occupied by the air.

Probably the gas and the vapour should actually be miscible and it is possible the repulsive force separating the two should be kept to a minimum, I am not quite sure =/