Clarification in assigning film coefficient

[Anonymous]

Hello everyone,

Assigning film coefficient to the outer wall is okay. 

but suppose hot fluid is moving inside the pipe then should we assign film coefficient on the outer side of fluid which is attached to internal part of pipe?

if no then why? and if yes then what should be the ref temperature. ?

please see the attachment for more clarification to my doubt.

regards,

Akshay Kumar

[Anonymous]

Hello everyone,

Assigning film coefficient to the outer wall is okay. 

but suppose hot fluid is moving inside the pipe then should we assign film coefficient on the outer side of fluid which is attached to internal part of pipe?

if no then why? and if yes then what should be the ref temperature. ?

please see the attachment for more clarification to my doubt.

regards,

Akshay Kumar

[Jon.Wilde · Accepted solution]

We can only assign film coefficients (in fact all surface boundary conditions) on the outer boundary of the model. CFD will calculate that inner one for you based on local temps and flow speeds.

Easy peasy, one might say 😉

In your case, as you are modelling a phase change, you absolutely must model the solid outside the fluid, so there is no other option for you. Keeps things nice and simple!

Does that answer your question?

Jon

[Jon.Wilde · Accepted solution]

We can only assign film coefficients (in fact all surface boundary conditions) on the outer boundary of the model. CFD will calculate that inner one for you based on local temps and flow speeds.

Easy peasy, one might say 😉

In your case, as you are modelling a phase change, you absolutely must model the solid outside the fluid, so there is no other option for you. Keeps things nice and simple!

Does that answer your question?

Jon

[Anonymous]

Thank you so much sir! Now I don't have any doubt about this.

[Anonymous]

Thank you so much sir! Now I don't have any doubt about this.

[Jon.Wilde]

Cool, glad to help 🙂

[Jon.Wilde]

Cool, glad to help 🙂