SimScale CAE Forum

Simulation Error - Boundary Condition

How can i make sure that there are no faces missing in the boundary condition?

Related Project:

Hi @sbasiima!

The step-by-step instruction explains this very well! \rightarrow Drone Tutorial

To make sure that no faces are missing you can use the Activate box assignment option shown in the top right corner. In that way you can make sure that you do not have to click every faces separately (which is a bit tricky in this case).

Let me know if you have any further questions. Good luck and all the best!


Hi Jousefm,
Ots very tricky indeed. I have tried it and there is no response. I have clicked it and it brings up activation or deactivate box assignments. What can I do?

Hi @sbasiima!

Glad to see you so engaged in finishing the project! Please have a look at this video explaining the Active box assignment: SimScale Release: Box Selection

Let me know if that helps! Good luck!


Hi Jousefm,
I checked out the box selection but it didn’t work.


@sbasiima, just checked your setup.

So your original question,

With the new workflow you can flick between the boundary condition definitions to see what is highlighted:

Here we can see that you have selected the bounding box as well as the drone for the ‘drone’ boundaries.

and here:

Slip walls have been selected for the symmetry.

and flicking between symmetry and slip walls you have missed the x high wall from either.

my general workflow here is as follows:

  1. Assign the inlet and outlet boundaries then hide them

  2. Assign the slip walls then hide them

  3. Assign the symmetry faces then hide them

  4. Assign the MRF then hide it

  5. ‘select all’ the assign to the drone

By the end, if you have done all the boundaries nothing will be visible!!

Kind regards,

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Thanks Darren,
Unfortunately i was impatient, i got your response late. I went ahead and ran the simulation with the error and i got an error message containing the following:
Probably a wall function boundary condition has been assigned to the bounding face of a MRF zone.please check your boundary conditions and make sure that boundary conditions are defined on the bounding faces of the MRF zones.
After seeing this message, i went back and deleted all assignments and re-assigned the faces according to this link. I have finished the instructions once again just wondering how to run the simulation again

Hi Darren,
I was successful ande now am running the simulation oncemore.

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Thnks Darren for your kindness. You were right. the problem is with the boundary condition.

Kind regards,