[omaralyahia]

I have narrow Vertical Rectangular channel, heated from both side. the flow direction is downward flow, at the same power level and boundary condition, if I applied the wall boiling model, the wall temperature would decrease much. For example at 10 kW the maximum wall temperature is 115 C, and at that power there is boiling and bubbles. So if in need to see the void fraction, I shall apply the wall boiling model, and after that the wall temperature decrease to around 85 C, however at this temperature there is no boiling anymore. So my question is how to match the wall temperature before and after applied the two-phase model (Wall boiling model)?

Your time response is highly appreciated
Thank you so much
Best Regards
Omar Al-Yahia

[ghorrocks]

I do not understand your question. What changes and results in the temperature dropping to 85C?

[omaralyahia]

my question is; when I applied the wall boiling model, the wall (surface) temperature is reduced by around 20 C when I used single phase.
for example : at the same power and same B.C, if I used normal single phase model I got wall temperature 115 (just example) and at this temperature we have boiling (in reality) so to see the void fraction and the location of ONB I applied the wall boiling model, but when I applied that the wall temperature becomes 85 and this value there is no boiling so I cannot predict void fraction

[ghorrocks]

First of all you have to make sure the basics are under control: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

But if you show that is all OK and are still getting this result I cannot explain your result. You would have to look into the details of the wall boiling model and how you are applying it.

[omaralyahia]

I did that
but I'll make sure again
Thank you soooooo much for your help