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Dear All,

let me firstly talk about the case (example) in the COMSOL support.
3_flowint_timeint.mph 882 KB
Total mass integration

The link is www.comsol.com/support/knowledgebase/1042/

The case includes a top convective flux while the middle right is sink reactive flux. So, the case is trying to demonstrate the space and time integration, and then give the total mass.

The question is here. I want to check the case is right or NOT by plot the mass balance between mass difference in the domain after period time computing. The Mass_diffrence would approach to 0 as expression: Mass_diffrence=Tot_mass+Tot_react-(Tot_Ic0-Tot_Ic). Where, Mass_diffrence is the mass difference for consistent checking, Tot_mass is the total mass out from top convective flux, Tot_react is the total mass out from middle right boundary, Tot_Ic0 is the total initial mass, and Tot_Ic is the total mass at the domain after period computing. All of these mass values are integrated by the same way as Tot_mass in the support example case. As the expected RIGHT result, the value of Mass_diffrence would be very close to 0. But this case is not consistent because the difference is NOT close to 0. I am very strange what the hackers are? This problem looks very simple. But the result is big deal for the COMSOl operation because of nonconsistent results. So, could anybody help to look at this case and give some suggestions/comments on how to make it consistent?

I appreciate,

Best regards,