The nusselt no.

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  • Last Post 04 June 2019
aminhgn posted this 01 June 2019

Hi, 

I am modeling multiphase flow, water, and air. there are mass transfer and heat transfer between two phases. I would like to get sherwood no and nusselt no in results. anyone can help me with it. Thanks

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Kremella posted this 03 June 2019

Hello,

You might be able to use the Custom Field Functions to define 'Nusselt' and 'Sherwood' numbers in your simulation. You might need to get obtain the correct heat and mass transfer coefficients from your simulations. Is there any phase change in your model?

Thanks.

Best Regards,

Karthik

aminhgn posted this 03 June 2019

Thank you for your reply. Yeah, water change to water vapor. I do not have lot problem with Sherwood number because fluent can calculate mass transfer if I go to report-surface integral-mass weighted average-phase interaction but I couldn't find anything similar for heat transfer.

Regards,

Amin

abenhadj posted this 03 June 2019

Create both bis Custom Field Function, UDF or Fluent Expression.

Best regards,

Amine

aminhgn posted this 03 June 2019

Thank you for your reply. can you help me about creating for nusselt number? what should i write for UDF? 

aminhgn posted this 03 June 2019

I know the equation. the equation has local heat transfer rate, width of duct, thermal cond, and temperature of interface and bulk temp. the only thing missing is the heat transfer rate?

abenhadj posted this 03 June 2019

That is will be the surface heat flux to get the HTC to get nusselt!

Best regards,

Amine

aminhgn posted this 03 June 2019

that's my problem. surface heat flux is zero. because the heat transfer happens between two flows and the walls are adiabatic.

abenhadj posted this 03 June 2019

Are you using Eulerian Multiphase model?

Best regards,

Amine

aminhgn posted this 03 June 2019

because I do have two imiscible flow (water and air) and it's falling film, i am using VOF

abenhadj posted this 04 June 2019

You need to formulate it based on jump conditions at the interface by using the temperature gradients times heat conductivity on each side of the interface. Bear in mind that the heat transfer like momentum transfer in VOF is infinite or pretty large.

Best regards,

Amine

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