Learning Forum

[Ella Chapman]

Hi everyone, 

I'm pretty new to ansys and I've been struggling to develop a simple forced convection solution (On Fluent). It's essentially a solid block within a domain that I've modelled as the fluid, but the problem is that there is no heat being produced? I have given a singular wall a heat flux while the others have been assumed adiabatic. Gravity is on, incompressible ideal gas for the density of air, SST k-omega. What have I done wrong?

[Atharva Nagarkar]

Hello Ella,

Please find the link below to an Ansys Course on setting up a turbulent forced convection problem. This course should act as a guideline for you to setup a forced convection problem. You may have to adjust some parameters and settings based on your case.

Turbulent Forced Convection | Ansys Innovation Courses

Additionally, I am attaching a link below from the Ansys User's Guide regarding forced convection. Please check the different sections if applicable.

15.2. Modeling Conductive and Convective Heat Transfer (ansys.com)

If you are not able to access the links, please refer to this forum discussion: Using Help with links (ansys.com)

Thanks!

[Rob]

No heat anywhere, or no heat passing from the solid to fluid? 

[Ella Chapman]

Yeah, I have no heat developing on the surface despite having a heat flux

[Rob]

What is the heat flux attached to?  Please post some pictures as I'm running low of tea leaves, and the crystal ball is off for repairs! ;) 

[Ella Chapman]

I've attached the heat flux to one of the walls on the solid - not too sure what pictures you are wanting but I've tried my best :,)

[Rob]

OK, I think I know what's going on. You didn't do share topology in the geometry tool (SpaceClaim), so have a nonconformal mesh. In itself that's OK (not ideal, but OK) but you've then added a wall heat flux to the connecting wall. If you're lucky the solid is warming up, but most likely nothing is getting warm. 

The safest fix is to go back to the geometry step and ensure you've shared topology: that'll be covered in the tutorials and/or course on Learning. Mesh the geometry, please review the course/tutorials there too for some guidance.

In Fluent you need to decide where the heat is coming from. Ie is the whole solid hot (eg a computer chip) or is just one wall heated? The former is a source term, the latter a wall boundary condition (as you set in the above case). However... now you fixed the geometry you'll have a few wall & wall:shadow pairs (coupled walls) do NOT change that coupled setting without understanding what it does: it's covered in the Fluent User's Guide. 

[Ella Chapman]

Hi Rob, thank you so much for mentioning the topology, you've solved one of my issues that I was dealing with. However, even if I assume that the entire solid is hot, I'm still getting no heat. 

[Rob]

Please can you post some images? Also do a heat flux balance on all surfaces. 

[Ella Chapman]

Hi Rob, I managed to fix it but thank you so much!!!!