Running a Transient Simulation animation

Project Support
1

Hey, I was just working on designing a multi-element rear went and I wanted to see the vortex shedding through a transient simulation analysis. However, when I tried to run a transient simulation, it took nearly 4 hours and only gave me 0.5s of analysis. I changed some of the settings in simulation control but I don’t know what settings I should have to get what I want. Any help would be amazing.

Here is the animation I want it to look similar to (First and Second GIFS): How to Detect Transient Effects in Steady-State Simulations? | Knowledge Base | SimScale

Here is the project: http://simscale.com/workbench/?pid=7445282753461925097&mi=spec%3A299ef215-6893-4249-b53e-3cce78931cab%2Cservice%3ASIMULATION%2Cstrategy%3A1&ps=analysis%2FsimulationControl

Thanks once again!

2

Hi @AayushShah, thanks for posting

I think the first point that needs to be raised in these sorts of cases is that transient studies using OpenFOAM are not trivial in any way - especially because of what you mentioned concerning the timestep definition. The timestep is highly dependent upon the Courant number, which in turn is given by the relationship between the velocity, cell’s edge lenght and timestep.

Here are some corollaries of this:

  1. The mesh needs to be very uniform and controlled, otherwise the timestep will be very low
  2. The higher the domain’s velocity, the harder it will be to run a transient study
  3. Usually transient studies are run for a very short time period (although you need to leave time for the fluid to pass through the entire domain at least 3 times)
  4. If you have very small elements, to keep a good accuracy the timestep will also need to be small

This youtube webinar has proven useful to many users who desire to run transient studies.

Cheers
Igor