HTC
 

Hi!

I'm new here. My name is Karol and I'm a student of Warsaw University of Technology (Poland). I've read a discussion about using commercial codes at school and yes, I'm using Fluent in my Thesis. Maybe it's wrong but I've already learned a lot and my value to the potential employer is bigger, I hope. In my country it's hard to get a job and companies look for employees already prepared to work, with knowledge of commercial codes they use.

I have problem with Heat Transfer Coefficients I got. HTC are half of what I expect to be. My question is: How is HTC calculated in Fluent?

My second concern is: How to set roughness in Two-Layer Zonal Model? When I used standard wall functions I could set roughness in boundary conditions/wall window, when I switched to Two-Layer that option disappeared.

Karol

Re: HTC
 

1)The magnitude of the heat tr. coeff depends on the temperature difference between bulk and surface. Since the cell at the wall doesn't 'know' the bulk temperature, you have to supply it as a Reference Value (Under 'Report' menu).

2) Fluent only supplies a Law of the Wall that is modified for roughness effects.

Re: HTC
 

Thank You Erwin! I'm going to check on the reference temperature on monday. I think that may be my problem.

Regards

Karol

Re: HTC
 

Hello Karol, I think, by default, FLUENT takes the reference temperature to be 298.15 K. You need change this value for your problem.

Thanks, Thomas