mass accumulation
 

Good day

I solve the problem of filling the big box (initial filled with air+CO2) with, for example, CO2. I use ideal rho=f(T,p). I have only 1 b.region. - inlet. But when I look the *.info file, the total mass of mixture is not the same as I expected. Additional information shows, that I have on the each time step (*.info) the SDRDT - mass accumulation by density change in time, kg/s. So my FLOW_in - SDRDT = FDIFF (mass balance kg/s).

But I suppose my FDIFF=FLOW_in.

What is SDRDT? Why did I get it and what should I do whith it?

Thanks in advance