Learning Forum

[Finlay Parson]

Hi all, I am trying to simulate a conjugate heat transfer simulation of a duct with two materials and constant flow of ethylene glycol through it as a cooling fluid. The duct has inner walls of aluminium and an outer copper wall with a component generating 25W with a maximum temperature of 95'C on the bottom of the duct.

When I run it for some reason I am not getting any heat transfer across from the component to the cooling fluid, the copper plate is being heated but there is no conduction into the aluminium plate or convection into the cooling fluid. I am not sure if it is something to do with the boundary conditions I am using, do you reccomend anything I can do to fix this?

Thank you in advance.

[Essence]

Hello,

Could you please share the screenshots of the mesh and the case setup panels?

[Finlay Parson]

[Finlay Parson]

Heat source BC 

[Finlay Parson]

Fluid-Al BCs

I was not sure what to have for the conduction BCs between the copper and aluminium plates, I caluculated the temperature at each boundary and entered that but I was not sure if that was the right way to do it

[Essence]

You can try to apply the heat source directly to copper volume. Do not apply any other thermal BCs for copper, aluminium or ethylene glycol as they will get coupled. Heat from copper should pass on to ethylene glycol through aluminium automatically.

[Finlay Parson]

So would I just leave the temperature BC at 0 and defult for the other wall BCs

[Finlay Parson]

I tried using the system coupling condition but it gives me an error message with; 

Selected option 8 for Thermal BC Type for zone wall-cu_top is not applicable, so skipping it.

 

[Essence]

No, you need to select the "Coupled" option in thermal BCs for the walls.

[Essence]

Not the system coupling. Please refer the Ansys guide link for more information (section 15.2.2.5):

 

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v232/en/flu_ug/flu_ug_sec_hxfer.html?q=conjugate%20heat%20transfer

[Finlay Parson]

Will have a look thank you for your help

[Finlay Parson]

Sorry to keep asking but I am not getting the option for thermal coupling between the two walls as an option I dont know if I am missing something;

[Essence]

 

Please try to check the mesh if there happens to be some connectivity issue. You should get the “coupled” option. 

 

[Finlay Parson]

Hi I managed to do it using mesh interface, creating a coupled wall BC between the copper and aluminium plate and another between the aluminium and fluid boundary. 

[Finlay Parson]

I am able to have heat transfer through the plates to the fluid but for some reason I am not getting any temperature gradient from the Al boundary into the fluid, it appears to all be one single temperature.

[Essence]

That is expected given the number of inflation layers in fluid domain. What is the value of y+ you applied? Try to have the y+ near to 1 and try to apply 8-10 inflation layers with growth rate not more than 1.2 in entire domain.

[Essence]

I also see the minimum temperature equal to -264 C  which is 9 K which I think is quite low. Is this expected? Could you show the Static temperature?