Reply To: Volume Fraction too Low. How to Improve?

[abdullahhassan]

Hi Rob, 

I started a new simulation as per your guidance, I calculated heat flux and wall temperture at tube side theoreticaly so I used temperature 288K at tubewall:1 and put coupled at the vapor - tube interface. As my point of focus was the heat transfer coefficient value at the tubewall due to condensation, and by ansys guide, it calculates 

h = q/(twall-tref)

so in reference values tab, I changed (temp, pressure, density, enthalpy) with respect to 292K and started my simulation. 

The simulation is giving negative value of heat flux at vapor-tube interface which means domain is releasing heat to tube wall. and heat transfer coefficient is positive so i think the direction for simulation is ok now.

what do you think?

secondly, if you see the below residuals, vapor are condensing and temperature is droping so everything seems straight but the heat transfer coefficient (surface integral>area weighted avg > surface heat transfer coefficient) at the interface has some abnormal residuals. you can check below. why is that happening. if other things are ok, should i neglect it?

The calculation has run for around 0.12 s.