simulation of water evaporation
 

Hello everyone,

I am trying to simulate the drying of a wet fabric with hot air.

Fluent support suggested to do this by defining a chemical reaction. The fabric is defined as a porous zone, so I chose Wall Surface as the reaction type. The reaction is defined as

1 h2o(l) + 0 h2o --> 0 h2o(l) + 1 h2o

h2o(l) is a site species, h2o a fluid species. site density is 1e-7.

My problem is that I can not impose the initial amount of liquid water h2o(l) of the fabric. Whatever I input for the site density, I get the same amount under Report/Volume Integrals/Mass Integral/Surface Coverage of h2o(l) after initialisation. After running the sim for e.g. 0.25s I can see in the contour plot of mass fraction of h2o that some vapour has been created in the fluid, and the report of the mass integral of h2o(l) shows that liquid water has decreased. But this also happens when the reaction rate is zero. I achieve this by setting the preexponential factor of the Arrhenius rate to zero. Then no vapour exists in the fluid after 0.25s, but despite of that the mass integral of liquid water has decreased to the same amount as with non zero Arrhenius rate. So I wonder what meaning the site density value and the mass integral in the Report panel have?

Regards, Markus