[AGoitia]

Hello fellow users:

I am currently working on a multiphase simulation of the caughing process using the VOF model. I am interested in monitoring the removal of the second phase fluid (which simulates the mucus) from the volume I am using. Trying to do this I defined two volume integral monitors: Mass-Integral/Phases/Volume-fraction/mucus and Volume-Integral/Phases/Volume-fraction/mucus.

The mass integral gives a value in units of (kg/m3)(m3) (which is suspicious) which I interpret as kg and the volume integral gives a value in units of (m3).

The problem is that when visualizing the plots of both monitors and comparing them they look very different althogh the should have least the same shape (the volume and the mass are only related by the density of the mucus which is constant). It can be seen in the next pictures.

massintegral_todo.jpg
mass-integral
volintegral_todo.jpg
volume-integral

Just after patching the mucus phase and doing reports of these two integrals the volume and mass values match perfectly by multiplying the volume value times the density. But as the simulation continues this values start to differ and they end up not matching at all.

The volume-integral gives me more confidence because it seems to stay at a constant value sometimes (which is to be expected until a drop of mucus exits the domain) but the mass-integral doesn´t make any sense to me. My continuity residuals are in the order of 1e-2 but that should not matter as far as I know.

I would like to know your insights reagarding this problem.

Thanks in advance