Reply To: Suddenly divergence in transient simulation with VOF

[Dato]

Yes, vapor will appear near the wall. Actually, I haven't do mesh independence analysis because accuracy is not the concern now. It's also because the huge amount of mesh due to the large scale model with 10mm pipe diameter while total length is around 20 meters. It's also a transient situation. Initial temeprature of water in the domain is 293K and it's expected to be heated to generate vapor.  

The whole domain reaches the fixed temperature is intended final result. But It takes more than 1 thounsand seconds to obtain desired result, which is calculated by other system code.  But it diverged after about hundred seconds as illustrated above. During the calculated period, vapour was generated. Do you mean mesh should be refined to achieve converge in the case?  But time consumption is really a great consideration. 

I think that one possible reason causing divergence is the pressure-outlet boundary condition. Sorry that I haven't make my case condition clear. Initially, whole domain is 293K, and upper volume is filled with air whose lower surface is level with the pipe extending into the tank. Then the water is heated and natural circulation is forming. Air will fluctuate irregularly. Whole device is assumed to be  placed at room temperature so I have set adverse flow temperature to 293K but actually it isn't. That's maybe the reason causing divergence with water heated. 

Do you have any advice? Thank you so much.