How to calculate heat transfer coefficient in FLUENT?

ReVl27 · November 11, 2015, 00:12

Hi, I'm working on a simple heat convection simulation for my class.

While working with FLUENT, I got trouble figuring out how to calculate the heat transfer coefficient in the "Thermal/Convection Boundary conditions menu".

Here is my problem:

The point of the simulation is to find the temperature distribution in the aluminum plate over time.

A 2D solid aluminum plate, with the top edge (red) maintains a fixed temperature of 650K. I defined the material as aluminum from FLUENT default database (thermal conductivity is 202 W/mK). The bottom edge (yellow) is where I'm setting up a convection boundary condition. The bottom edge is in contact with ambient air at 298K. So I entered 298K under "Free Stream Temperature" but I can not figure out the Heat transfer coefficient.

Could anybody show me how to calculate this number?

LuckyTran · November 11, 2015, 12:57

Technically, the heat transfer coefficient should be known for you to carry out your simulation.

The heat transfer coefficient depends on the flow field around the plate. What is the flow environment of the plate?

Is the plate in quiescent air so that it's a natural convection problem? Or is this a forced convection problem?

ReVl27 · November 12, 2015, 00:23

Quote:

Originally Posted by LuckyTran

Technically, the heat transfer coefficient should be known for you to carry out your simulation.

The heat transfer coefficient depends on the flow field around the plate. What is the flow environment of the plate?

Is the plate in quiescent air so that it's a natural convection problem? Or is this a forced convection problem?

Thank you for your reply Tran,

The air flow outside of the solid plate if laminar and this is a simple natural convection problem.

Is there any formula that I can calculate or even estimate the heat transfer coefficient?

LuckyTran · November 12, 2015, 01:44

There are numerous of correlations for downward facing plate in the form of Nusselt number as a function of Raleigh number or Grashof number.

Don't you have an undergraduate heat transfer text book? Or a heat transfer handbook? Or just do a simple lit search for natural convection on a plate.

You can also take an educated guess, via order of magnitude analysis and the Nusselt number should be 0<Nu<10 for laminar natural convection.

November 11, 2015, 00:12	How to calculate heat transfer coefficient in FLUENT?	#1
ReVl27 New Member Nam Nguyen Join Date: Jan 2015 Posts: 3 Rep Power: 11	Hi, I'm working on a simple heat convection simulation for my class. While working with FLUENT, I got trouble figuring out how to calculate the heat transfer coefficient in the "Thermal/Convection Boundary conditions menu". Here is my problem: The point of the simulation is to find the temperature distribution in the aluminum plate over time. A 2D solid aluminum plate, with the top edge (red) maintains a fixed temperature of 650K. I defined the material as aluminum from FLUENT default database (thermal conductivity is 202 W/mK). The bottom edge (yellow) is where I'm setting up a convection boundary condition. The bottom edge is in contact with ambient air at 298K. So I entered 298K under "Free Stream Temperature" but I can not figure out the Heat transfer coefficient. Could anybody show me how to calculate this number?

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November 11, 2015, 12:57		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,751 Rep Power: 66	Technically, the heat transfer coefficient should be known for you to carry out your simulation. The heat transfer coefficient depends on the flow field around the plate. What is the flow environment of the plate? Is the plate in quiescent air so that it's a natural convection problem? Or is this a forced convection problem?

November 12, 2015, 01:44		#4
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,751 Rep Power: 66	There are numerous of correlations for downward facing plate in the form of Nusselt number as a function of Raleigh number or Grashof number. Don't you have an undergraduate heat transfer text book? Or a heat transfer handbook? Or just do a simple lit search for natural convection on a plate. You can also take an educated guess, via order of magnitude analysis and the Nusselt number should be 0<Nu<10 for laminar natural convection.