Adding a second velocity field

Hi, I’m running a project trying to reduce the drag effect of the inter car gap cavity on a high speed train. I’m trying to add a second velocity field in the inter car gap to simulate an air jet blowing air over it to stop the air around the train from going into the cavity. I was wondering if someone could tell me if i have modelled this secondary velocity flow correctly,( i just literally added a velocity inlet as shown) or if there’s something I’m missing because it doesn’t seem to reduce the drag and if anything is increasing it.
My project supervisor seems to think that the air jet idea should reduce the overall drag on the train.

I don’t think there’s anything wrong at all with the rest of my model because my supervisor has looked at it before I added the “air jet” and said everything’s fine. I have included some pics below.

Any help given would be greatly appreciated.
Many thanks

Hi @ed20m2su,

Thanks a lot for posting at our forum :slight_smile:

Please make sure to post a link to your project!

I’ll try to work on a solution to your problem and get back later with my findings.


Hi @ed20m2su, sorry for the late reply,

Since I don’t have access to the project where you ran these simulations, I can only provide some general advice on the procedure to identify the issues with it. Some general questions to be made are:

  • Did you check your mesh’s quality and ran a convergence test for it?
  • Were the residuals behaving oddly? (convergence)
  • Where did you get the expected results from? Meaning: Are they coming from research (such as a scientific paper) or are they just a hypothesis?
  • Did you run an evaluation for the \mathrm y+ before running your simulation?

Tell me if that helps!