Simulations won't converge


#1

I’m not sure if I’m just expecting more of a convergence or if I’m doing something very wrong here, but I don’t know how to get my simulations to converge. Could really use some help figuring this out! Screenshots attached.

First settings are for the first graph. Second set of settings are for the bottom two graphs.

Also, very new to CFD and have basically been copying settings from projects I’ve looked at that are similar to mine (SAE Baja car).

Any help would be appreciated!!!


#2

Hi @OffroadIllini, can you pop a project link up?

Kind regards,
Darren


#3

https://www.simscale.com/workbench/?pid=8540861348426744264#tab_0-0

Here it is, was on private, but moved it to public for now. The help is greatly appreciated!!


#4

Hey @OffroadIllini, just so you know I’m looking at your project and will get back to you shortly :slight_smile:

Darren


#5

Great! Thank you!


#6

Hi @OffroadIllini, I think we need to revisit the geometry here. things like the bars, for a CFD analysis we can make them solid. The plates joining the frame have gaps and spaces and although this might be realistic for the construction it makes a CFD analysis unnecessarily complicated. What we need is an almost block like the model with as little detail as possible, I have improved the mesh setup which we can use once the geometry has been simplified. I’m gonna just hold until we have a CFD geometry if that’s ok? I think this is the best course of action.

Kind regards,
Darren


#7

Darren @1318980,

Okay, I can work on getting a more simplified geometry from my team that will work better. How do I go about making the bars solid? We export the body from Creo and I can only import a surface or a solid, it looks like I can’t choose which parts to do differently. As for your changes to the mesh setup, do you mean that you have changes to suggest? Or that you made a copy of the project with the changes applied?

Mason


#8

Hi Mason @OffroadIllini,

I dont know your design process, but I would have created the bars as solid thrn hollowed them. If you copy your project and go back removing these features making a geometry specifically for CFD. These are the sort of things that are causing issues:

Internal frames add complexity and play little in the role of external aerodynamics:

The shell around the could be represented as a solid thus removing unnessesary spaces:

This is the sort of thing you should aim for:

See how the nose is one solid, the bars are just solid representations and the shell between the bars dont have any gaps between them and the bars. A representation like this will be very close to detailed geometry but with less computational requirments and more importantly, beter stability (it isnt having to resolve down to air flowing withing the car.

The simpler we can make this, the more time we can spend on meaningful results.

Hope this helps, I would offer to help preparing the geometry but I dont use creo.
Darren