[Nheni]

Dear everyone,

My transient simulation parameters:
- I have a simple, closed 10 l cubic fluid domain with 3 gases mixtrure, one of them has 0 mass fraction initially. The walls are adiabatic, the fluid model is laminar( but I tried turbulent, too).
-Then I inject the third gas with the same temperature like initial temperature into domain through one small inlet.( The flow rate is 56 pa/s)
- The mesh nodes number is 36000 ( but I also tried better mesh), the time step is 0.05 s.

My expectations:
- the pressure increase
- the temperature stability
- the internal 2 gas mass stability in the domain
- the injected gas mass increase like I calculate

My problem is that despite the good courant number, the imbalance is not good enough, the temperature is increase, the internal gases mass is decrease and the third gas mass in domain is lower then I calculate. The pressure change is good. So,the gas masses are lost or transformed, which is clearly not in accordance with the laws of physics.

I am not sure, that the problem reason is the bad mesh and time step quality( because my inlet is much smaller then the volume) or some set up mistakes. Is there any special set ups for this case, which I has to use?

Is anyone has experiances about this problem?

Thank you for help.

Nheni