Learning Forum

[Onyedika Mbelu]

Hello,

Please, I am running a simulation with three phases and inlets, air, water and PCM. Water comes in at a high temperature to melt the PCM, air gets compressed because of this. I run it to about 4.5secs and I shut off the inlets and allow the water melt the PCM. I noticed that when I shutoff the inlet, air volume increases(which is not meant to be so) while pressure and temperature decreases. I also noticed that water volume decreases which is weird and wrong because my system is incompressible(boussinesq). I don't know how to solve this problem, can someone please suggest to me how to fix this?

 

Thank you.

[Rob]

As a guess you're losing mass of another phase? This is typically caused by a mix of convergence and mesh resolution. During the earlier stage, if water is coming into the domain and PCM is already present where does the air go? 

[Onyedika Mbelu]

No the air doesn't go. In the earlier stage, we have a case of Adiabatic compression, the air gets compressed while the water volume increases because there's a steady addiition of water at the inlet.

[Rob]

But if air is fixed density what happens?  Consider the physics, not just the simulation theory. 

[Onyedika Mbelu]

The air is taken as an ideal gas from the onset of the calculation, which makes it behave to be adiabatically compressed.