SimScale CAE Forum

Help creating a convective heat transfer model


I’m not experienced with the simscale software, so I’m not sure where I’m going wrong so I’m just going to explain my goals and what I’ve tried.

In this image is my model. My goal is to simulate a heater/fan blow in air from the raised blue square on the left, and then there to be outlets on the 0.25" raised portions around the model (the light blue on top, orange on the front face, circle on the left), while the other portions remain solid walls. I’ve tried running a simulation with the inside face of the square chosen as a velocity inlet and then all of the faces of the objects I want to outlets as velocity outlets, but my simulation fails. What should be the correct set up for this?


Hi @stomp, unfortunately if all inlets and outlets are defined as fixed velocity the simulation will fail due to the continuity cannot be satisfied. It is best to set the case up with velocity inlets and pressure outlets i.e. you know the velocity entering however we just say that it is exiting to atmosphere.



Ah interesting, that makes sense.

Unfortunately, I tried that but I still had a failed simulation, these are the settings I have. Thanks so much for your help so far


I’m hoping someone could still help me out, I still haven’t gotten it to work.


Hi @stomp,

Are you performing a CHT simulation? Because your analysis type right now is incompressible flow even if your boundary conditions are now correct. Maybe try setting your first simulation (the one where it is CHT and laminar but has the wrong outlet BC) with the corrections Darren mentioned?

Let us know how it goes.




Oh right sorry, I’ve been experimenting with both simulations, so I accidentally posted the wrong screenshot, it still doesn’t work with the CHT. Am I supposed to be choosing all of the faces of the solid I want to be an outlet? Because that’s how I currently have it set. I have screenshots of my current settings here, but I’ve been simplifying the simulation to just a single outlet at the circle on the side until I can get just that working:


Hi @stomp,

Pressure outlet should be gauge pressure fixed value and zero. So try that out. Inlet velocity seems fine. You need to define your solids and fluids. Have you tried following an example project like this?

Try to follow it and set it up similarly. Let us know how it goes.




Ah okay got it thank you!


Hey guys sorry again, but I’ve been trying to follow tutorials and still have had no luck and feel like I’m just lost. I tried running a simulation where everything is a boundary wall, just to have as few variables as possible and my simulation still failed, so I feel like there must be a problem with my CAD design, but I don’t know what it could be. Thanks for your help



let me tag our CHT expert @sjesu_rajendra here who might give you some useful tips on geometry modification to make your case work before you invest more time into it without getting an added value .