[sidharth9426]

Dear Experts,
I am working on a project of Under Hood Thermal Management on StarCCM software.
I need to apply various loading conditions for the project.
So wanted to know that,

1) If I want to test a vehicle at 240Km/h then where should I add this condition, is it at the inlet of the control volume, or anywhere else?

2) How to enter the gradients of the hill in the software?

Thank you,
Sidharth.

[fluid23]

Those questions depend on how your model and domain are setup. Can you share a picture or provide a better description?

[sidharth9426]

Dear Sir,
Actually I am dealing with a project of underhood thermal management, also I am new to the star ccm solver.
In the project I need to find the temperature distribution Under the hood when,

1) The vehicle is moving at max speed.

2) The vehicle is moving a 7% hill gradient at 40Km/h and vehicle is fully loaded

I am clear about the first question, but need some advice for the second question.

My query is that where should I add these boundary conditions in the solver. I am unable to get the options in solver whereby, I can add 7% gradient and the fully loaded condition i.e vehicle has taken its max weight of 1600 kg.

Please guide me for the same.

Regards,
Sidharth.

[fluid23]

Boundary conditions governing forward speed should be applied to your far field boundaries. You should be modeling the air around your objects as well as any solids you need to resolve thermal gradients in. The air volume surrounding your vehicle should probably extend at least 5-7 body lengths up stream. 10-15 downstream and 5-7 to the side. (You might be able to get away with less, but from an external aerodynamics point of view, this is where you want to be).

As for the gradient and load, these are going to manifest themselves as as changes in engine temperature. So under no load you will have a certain temperature condition inside the engine. When you add weight to the car, the engine has to work harder to achieve and maintain the same speed. This results in a temperature offset. Same thing is true for hill gradient. You would need to have information about how the vehicle and engine combination respond to these to determine what temperature change would be. (This is out of my field of expertise).

You aren't actually trying to model the whole engine are you? That over complicates things. Without seeing pictures of your model I am not sure I can offer much more advice.

[sidharth9426]

Dear Sir,
Thank you so much for the guidance. And I am not really dealing with the engine, I just need to simulate the air flow inside the engine compartment at the loading conditions mentioned above.

And I am having the CAD model right now, of the full vehicle. I just started on the CFD model.

Also sir as you told "The air volume surrounding your vehicle should probably extend at least 5-7 body lengths up stream. 10-15 downstream and 5-7 to the side", I just wanted to know that is there any thumb rule which we follow while deciding the size of control volume.? If you can guide me along this, this will be again a great help. ..

Thanking You,
Sidharth.

[fluid23]

The sizes I mentioned are what I use as a rule of thumb for my CFD analyses.

[sidharth9426]

Okay Sir, Thank you again ... Are you also dealing with the various CFD analysis on the vehicle?

[fluid23]

I work with mixed internal/external flows. Primarily aircraft inlets looking at distortion, pressure loss, etc...

[me3840]

For the gradient of the hill you're climbing, as MBdonCFD says, this will manifest itself as load on the engine. You should be able to calculate how much power the engine requires to overcome to travel uphill at the given speed. Then you can use that as a boundary condition for something like a dual-stream heat exchanger model to put heat into the flow.