# Wall Thickness for RPI Wall Boiling Model

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• Last Post 03 February 2019
• Topic Is Solved
farizanluthfi posted this 03 February 2019

Dear all,

Please give me some strong justification for what is the difference in putting wall thickness in the simulation in terms of dealing with boiling heat transfer? I have some calculation for determining the difference between the outer wall temperature and inner wall temperature and the result is 32K.

What will be the main effect if we don't put any wall thickness if the temperature difference is around 32K. Highly appreciated for your consideration.

Thank you,

Best Regards,

abenhadj posted this 03 February 2019

Zero thickness wall is the default behaviour: No heat resistance so outer wall temperature is equal to inner wall temperature.

Best regards,

Amine

farizanluthfi posted this 03 February 2019

For this different is around 32K, is that necessary for me to build the wall thickness so there will be heat resistance that defines the different temperature between inner and outer wall temperature?

Thank you,

Best Regards,

abenhadj posted this 03 February 2019

Yes: 134 kJ/kg is the imbalance if you do not account for this temperature drop.

Best regards,

Amine

farizanluthfi posted this 03 February 2019

Okay, I will determine the wall thickness in the B.Cs of the Fluent. The thickness is about 3.5mm so I guess it would bring miscalculations if I didn't put it on my case.

Thank you,

Best Regards,

farizanluthfi posted this 03 February 2019

I have tried your way for handling the boiling heat transfer case, but when I put default URF, it could get me diverged directly. Otherwise, if I alter the URF then the case is still running until 2000 iterations.

Here is the URF that I used in my case:

density = 1

body forces = 0.5

vap. mass = 0.5

vol.fraction = 0.3

turb. kinetic energy = 0.3

turb. dissipation rate = 0.3

turb. viscosity = 0.5

energy = 0.6

Highly appreciated for your kindly responses. Thank you.

Best Regards,

abenhadj posted this 03 February 2019

Try if possible to ramp URFs and fluxes as your solution evolves.

Best regards,

Amine

farizanluthfi posted this 03 February 2019

Okay, I'll do my best then I will update it to you again.

Thanks,

Best Regards,