Error in outdoor_airflow_2d example file

grasshopper butterfly
1

Hi,

Thanks for the update of butterfly. This is great! Super excited now.

However, I came into a issue when running the outdoor_airflow_2d example case. It ran but did not converged. Here is the error from report. Any clue?

"
Time = 6

smoothSolver: Solving for Uy, Initial residual = 0.5378333, Final residual = 7.5936467e+024, No Iterations 1000
smoothSolver: Solving for Uz, Initial residual = 0.52501375, Final residual = 3.1806038e+024, No Iterations 1000
"

Best
Bing

2

hi @Bing

It seems to be a meshing issue.

Make sure snap is toggle to true in the snappyHexMeshdict component and Increase of 1 or 2 the refinement levels of your geometry.

Let us know
Best
Olivier

3

Thank you for your reply.

But no luck not working. I increase refinement 2 level and turn snap on. Error as follow:

"
Time = 4

smoothSolver: Solving for Uy, Initial residual = 0.53778586, Final residual = 1.3426522, No Iterations 1000
smoothSolver: Solving for Uz, Initial residual = 0.30962378, Final residual = 0.87836996, No Iterations 1000
done!
"

4

@Bing
I finally took a proper look at your definition and managed to get it to run. There is somehow an issue when running 2d simulations where the wind tunnel is defined by 1 cell along the Y axis ( in your case). It seems that when you add refinement levels, your wind tunnel has then more than 1 cell on the Y axis.
You can improve the mesh density with your BlockMeshdict by adding cells alors the X and Z axis and also maintaining a square proportion by reducing the width of the wind tunnel.
02_1_indoor_airflow_2d_error.gh (430.2 KB)

Capture1
Capture1.PNG1990×720 136 KB

5

Hi Olivier,

Thank you for taking your time for the reply.

However, I think you confuse about the two cases. In this post, we are talking about outdoor case but you are responding to another post talking about indoor case.

For this outdoor case, the issue is the case is not converging with the mesh. Your response point out the issue. Playing with the _cell_count in blockMesh seems the solution. For this case, I put {1, 20, 10} and then the case works well.

I tested the indoor case as well, but will response in the other post, to reduce confusion.

Thanks for helping.

Best
Bing

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