Pure diffusion quaestion
 

Hi,
Problems with equilibrium concentration distribution in pure diffusion (no flow eq. activated) problem.
Setup: the rectangular domain divided into two equal parts. Two incompressible ideal gases with different molecular weights (ratio 2:1) fill each its half of the domain fully - initiated using patch, e.g. left c(firstgas)=0, right c(firstgas)=1. Steady solution should be an equilibrium uniform concentration distribution, i.e. 2/3 of one gas and 1/3 of the other - BUT IT IS NOT!!! some mass is missing...
Tried the same with heat - again the equilibrium temperature is not the same as it should be accounting the initialization patch.
Please help,
Thank you.