Blown diffuser simulation

Project Support
1

Hi, I’m a relatively new to simscale and I’m looking for some help understanding how to achieve a simulation for a blown diffuser concept. I have a model of a car rear diffuser with two pipes situated over the diffuser exit. I need a flow region around the diffuser model to simulate the airflow under the diffuser but I also need to be able to specify a different velocity for air exiting the two pipes.

I’m now reasonably familiar with setting up CFD simulations in an enclosure flow region but I’m not sure how to setup the above scenario. Once I have a flow region defined I can only select boundary conditions for the external faces of the enclosure, so no way to specify an inlet and outlet for the pipes. I also tried to setup an open inner region for the pipes but so far have failed to define the inner region correctly. Is defining an inner region for the above scenario the correct approach? May be you need multiple enclosures? I had a search around for a similar public project and only found one which as it turns out was empty.

Regards
Richard

2

Hey Richard!

Sorry for the delayed response, do you mind sharing your project if you have one?

Here is an example project: SimScale - once you share yours we are able to give you additional hints on your setup and how to proceed.

Best,

Jousef

3

Hi Jousef, thanks for getting back to me.

I think I have managed to prove I can simulate what I need to. I had several attempts and failed but then used a very simple model to prove the simulation. I simply setup the pipe exits as inlets with a different air velocity and I can see the effect that has on the wake.

FYI the project is at SimScale

I think this gives me enough confidence to try with a more accurate model.

Regards
Richard