SimScale CAE Forum

Fatal I/O Error crashing the simulation

After finishing the simulation setup, running the simulation stopped after 1 hour due to Fatal IO error which I can not specify why did that happen. I have followed the same procedure done in the Simscale Aerodynamics workshop (session 2) which simulates the full car using porous medium and MRF concepts. Here is the project link: (, if anyone can help. Thank you :slight_smile:

Hi @heshamzahw!

First of all sorry for the late response- completely overlooked the post. :neutral_face:
Looking at the geometry I think there need to be some fixes made in terms of watertightness as well as the refinements (with 1066 illegal cells). @PowerUsers_CFD, anything specific you want to add here?

All the best!


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Hi @jousefm,

Thank you for your help. Could you please give me a link illustrating the water tightness or explaining how to apply these fixes?


Hi @heshamzahw,

Watertight geometries simply mean that the geometry should be enclosed and a solid. Sometimes, your CAD model is just a series of empty graphical representations and they don’t actually have any defined surfaces that the solver can identify. So while you might see a geometry, in actual fact it is just a bunch of data and not an actual solid.

To fix this you have to refer back to your chosen CAD software. There are multiple ways to ensure a solid is watertight, of course with increasing complexity, the more difficult it is to ensure such geometries are not only solid but watertight hence simplification and De-featuring is needed. For how to apply such methods to your geometry will require some googling based on what CAD software you’ve elected to use. A couple of the more popular CAD softwares do have automatic functions where they can check watertightness and even fix issues in the model to make it watertight. You’ll have to google around on what the specific steps are.

Hope this helps!




Hi @Get_Barried
Thank you for this information, of course it helps a lot and I will work on it :wink:


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