Learning Forum

[oliveira1820]

I have a 3 cm recipient with liquid water and air initially. Then I apply a 900W energy heat source in the middle, and water vapour forms near the source and condenses near the cooled walls. I expect that all the fluids mix and that phase and mass transfer between the gas/liquid water occurs. Notice that I expect a average pressure near to 30 bar, so there should be like 85% or more of liquid water and little gaseous water at the "end".



For what I saw in my research I can´t decide if the best option is Thermal Phase Change Model or Droplet Condensation Model. Can anybody help me?

[DrAmine]

Hey, You will have to use the Thermal Phase Change model or your own mass transfer models. The Droplet Condensation Model is useful for situations where a dry or near saturation  two-phase flow undergoes rapid pressure reduction leading to nucleation and subsequent droplet condensation.

[oliveira1820]

Thank you!! One more thing, I suspect that the air, vapour water and liquid water have continuous separated domains, how can I be sure if the Free Surface model applies to my simulation or that the fluids mix or not and this model doens´t suit me?

[DrAmine]

Free surface model within the one fluid framework apply only if the flow is either dominated by gravity or drag or both but the "dispersed" fluid particles are in equilibrium with the continuous phases. That means this would match cases with regions of zero to low entrainment and discernible interface. With free surface activated you have additionally to afford for resolving the interface between the phases. 

You can start with one fluid approach for momentum but separate temperature fields and enable thermal phase change.

 

[oliveira1820]

But how can i additionally to afford for resolving the interface between the phases?

 

Best Regards