Altair RISE

A program to recognize and reward our most engaged community members

Nominate Yourself Now!

Heat transfer problem

Good afternoon, I have a question need some heat transfer experts help me to answer.

It is related to the heat convection coefficient.

For example, I have an object (blue) as shown in the picture below that I have been defining its boundary conditions, including heat convection coefficient of 12.5.

And now I have it in contact with another object (orange). Can I still define the rest of the expose surface as 12.5?

If not, how do I calculate this difference or another value for it?

Do we have a way to characterize heat transfer coefficient for modeling?

Last one, is the value of heat transfer coefficient depending on the object? I mean object in orange, can I defind its as 12.5 on the boundary as well?

Thank you so much!

Jerome.

Find more posts tagged with

AcuSolve

English

Flux

HyperMesh

HyperMesh CFD

Accepted answers

Jagan

Thanks Jadan.

I am not sure how to find out the convective coefficient using a non dimensional numbers, if fact, do you have any example?

I am parametrically change the value and see which one match up at the momet which is very time consuming.

Thanks,

Jerome.

How did u arrive to the value of 12.7 W/mK and is this a forced or natural convection?

You could refer the following to analytically determine heat transfer coefficient but the most preferred and accurate way is to run a CFD simulation.

Forced Convection:
https://www.engineeringexcelspreadsheets.com/2011/03/forced-convection-heat-transfer-coefficient-calculator/

Natural Convection:
https://www.engineeringexcelspreadsheets.com/2011/05/natural-convection-heat-transfer-coefficient-calculator/

All comments

Payal Pawar_20288

Hi,

Can you let me know which Altair product are you using so that I can direct your question to the proper forum?

jerometeoh917

Thanks Payal.

I am using the Flux and Hyperworks.

fzidat

Hello Jerome;

As you know in Flux those coefficients are inputs!

From my point of view, if the bodies are in contact, so there will be thermal conduction, and remaining faces / lines will be defined with convection!

Since i am not really an expert in this domain i added your request to the AcuSolve, and Hyperworks CFD group, so you may have more chance to get an answer from experts.

Regards

Jagan

You can specify convective coefficient to the exposed faces with appropriate reference temperature.

If both the orange and blue objects are exposed to same ambient conditions you could use the same convective coefficient value.

Did you analytically find out the convective coefficient using non dimensional numbers? if so, you could do that with the orange object too. Or else you could run a natural convection simulation in cfd and calculate the value.

jerometeoh917

Thanks Jadan.

I am not sure how to find out the convective coefficient using a non dimensional numbers, if fact, do you have any example?

I am parametrically change the value and see which one match up at the momet which is very time consuming.

Thanks,

Jerome.

Jagan

Thanks Jadan.

I am not sure how to find out the convective coefficient using a non dimensional numbers, if fact, do you have any example?

I am parametrically change the value and see which one match up at the momet which is very time consuming.

Thanks,

Jerome.

How did u arrive to the value of 12.7 W/mK and is this a forced or natural convection?

You could refer the following to analytically determine heat transfer coefficient but the most preferred and accurate way is to run a CFD simulation.

Forced Convection:
https://www.engineeringexcelspreadsheets.com/2011/03/forced-convection-heat-transfer-coefficient-calculator/

Natural Convection:
https://www.engineeringexcelspreadsheets.com/2011/05/natural-convection-heat-transfer-coefficient-calculator/

jerometeoh917

Jagan. Thanks. This is a natural convection.

I kind of just adopted the range from an online source and run parametric sweep simulation to match the cooling curve.

Ovando_RBB

Hi there,

It all depends on what kind of application you considering. If it is for the purpose of simple illustration, you can use the same heat transfer coefficient at all the walls. A film coefficient of 12.7 W/(m^2*K) seems reasonable for an exposure to atmosphere natural convection.

On the other hand, if you need a more precise estimation on the film coefficient; you will need to add CFD to your solution environment to have a more detailed temperature profile.

Hope this comment helps!