Learning Forum

[michaelmaalouly]

Hi,

 

I am trying to simulate a boiling flow on fluent using the Eulerian model. But the simulation keeps diverging as soon as gas starts to appear. The continuity residual skyrockets after the boiling start. I have tried both RPI boiling and CHF. Nothing is working it keeps blowing up. Basically on any setting, when the gas residuals start, the continuity residual goes above 1e01 and continues increasing until it reaches 1e10 or something around that and it crashes.

I was able to run the same simulation using VOF. However, VOF does not allow you to see bubbles or manipulate the case properly. 

Would anyone have any advice about how to make the eulerian model work?

P.S. I have tried refining the mesh, it does not seem to be a mesh issue.

 

Thank you! 

 

[DrAmine]

ensure that your grid is coarse twirls the heated wall with yplus largen then 30. RPI better in vertical pipe flow configurations. Start with only drag and dispersion and ramp the heat flux starting from low value.

[michaelmaalouly]

Hi Amine, 

Thank you for your response. 

 

I tried what you mentioned in your comment the simulation went blew up earlier than it usually does. Having a yplus of larger than 30 for my problem makes it harder to see bubble formation as the simulation is a circular horizontal pipe with heated walls. 

Cheers,

Michael

[DrAmine]

Sorry but that is the recommendation for RPI boiling. Add more details about your case. You won't see resolved bubble formation. The bubbles are modeled and not resolved.

[michaelmaalouly]

Oh okay, because I have seen a few simulations showing bubbles but that's probably using a UDF.
my case is a 1mm pipe with a length of 200mm. The fluid is CO2 and saturation temperature is 288.15 K with a heat flux of 10kW/m2.

[DrAmine]

Okay.