[ianjikar]

Hi,

After running the snappyHexMesh it creates folders for first 3 time step and also it the meshing start from the first time step rather than than the start time,0.

Can someone tell me why this is happening. I want it to create mesh for time=0 only.

I have attached my snappyHexMeshdict file

[akidess]

It's happening because that's what you told it to do. Set your startTime in controlDict to 0, and run snappyHexMesh -overwrite.

[ianjikar]

Originally Posted by akidess

It's happening because that's what you told it to do. Set your startTime in controlDict to 0, and run snappyHexMesh -overwrite.

My start time is 0 in controldict. I will try running snappyhexmesh -overwrite

[aow]

You could also copy the polyMesh directory inside the final time directory to the constant directory in the main case directory and then delete all of the time steps past 0 before actually running your case, but using the -overwrite flag is clearly easier.

In general though, each of the 3 potential operations (castellatedMesh, snap, addLayers) you can do using snappyHexMesh are done in separate time steps so you really only need the last one, providing each step was completed successfully. Also, if you aren't happy with the results of say the addLayers option, then you could use one of the partway steps that are saved in different time directories if building your mesh takes a long time as a starting point to redo the addLayers step. I think that's one of the main reasons they write each step separately instead of overwriting them by default, but I guess this is unnecessary if everything works okay for you.

[ianjikar]

Originally Posted by aow

You could also copy the polyMesh directory inside the final time directory to the constant directory in the main case directory and then delete all of the time steps past 0 before actually running your case, but using the -overwrite flag is clearly easier.

In general though, each of the 3 potential operations (castellatedMesh, snap, addLayers) you can do using snappyHexMesh are done in separate time steps so you really only need the last one, providing each step was completed successfully. Also, if you aren't happy with the results of say the addLayers option, then you could use one of the partway steps that are saved in different time directories if building your mesh takes a long time as a starting point to redo the addLayers step. I think that's one of the main reasons they write each step separately instead of overwriting them by default, but I guess this is unnecessary if everything works okay for you.

Ohh. Ok thats what happens. I used the overwrite feature and the meshing was good, but i guess your info would help me in future. Thank you.