Just adding another question of doubt in the context of the thread. 

I have tried two different simulations, 1. Case with mixture of vapor/air as my primary phase (species transport) and secondary as liquid.

2. Case with liquid as my primary phase and mixture as my secondary phase. 

In case 1, everything seems physical. Primarily, I would expect mass transfer rate to be zero after initialization before starting the simulation and this is correct in case 1. However, in case 2, where liquid is my primary phase, after initialization, my mass transfer rate is always a "non-zero value". There is unstable solution and possible divergence which I believe could be attributed to this issue. 

Can anyone kindly explain why fluent intreprets this way?  

Thanks in advance

PS: I use FLUENT 2020 R2