[Tasneem]

Hello fellow CFD students and researchers,

I have two questions related to mesh generation using Star CCM+;

1. May I know if I can change the ratio of Prism Layer Stretching after certain number of layers. I am doing a simulation of internal flow in a pipe at high Re. I would like to have for example 50 prism layers but the prism layer stretching changes from 1.3 for the first 10 layers near the wall and change to close to uniform stretching (for example 1.0001) for the rest of the layers. I tried using volumetric control by adding cylindrical shape inside the tube it created few other problems.

2. This question I might be getting an obvious answer but I would like to hear the opinion or suggestion from fellow CFD researchers. I am using Trimmer mesh for my pipe simulation. The mesh that I got specially at the wall of the pipe is like the connections of straight lines. Is there any way to do if I want to have a curve mesh at the wall (I mean a smooth mesh at the wall) but still using trimmer as the mesh shape.

3. If the answer of Question 2 is no, may I ask if you have suggestion of any open source software that using GUI that capable to generate good mesh for a pipe.

I would really appreciate your guide and suggestion. Thank you.

[me3840]

1. Not for unstructured meshing. You can do this if you use the directed mesher.

2. No, the trimmer cannot be body-fitted. You can use the directed mesher to make these kind of cells though.

3. I would suggest you try the directed mesher considering my answers here.

[Saima]

Originally Posted by Tasneem

Hello fellow CFD students and researchers,

I have two questions related to mesh generation using Star CCM+;

1. May I know if I can change the ratio of Prism Layer Stretching after certain number of layers. I am doing a simulation of internal flow in a pipe at high Re. I would like to have for example 50 prism layers but the prism layer stretching changes from 1.3 for the first 10 layers near the wall and change to close to uniform stretching (for example 1.0001) for the rest of the layers. I tried using volumetric control by adding cylindrical shape inside the tube it created few other problems.

2. This question I might be getting an obvious answer but I would like to hear the opinion or suggestion from fellow CFD researchers. I am using Trimmer mesh for my pipe simulation. The mesh that I got specially at the wall of the pipe is like the connections of straight lines. Is there any way to do if I want to have a curve mesh at the wall (I mean a smooth mesh at the wall) but still using trimmer as the mesh shape.

3. If the answer of Question 2 is no, may I ask if you have suggestion of any open source software that using GUI that capable to generate good mesh for a pipe.

I would really appreciate your guide and suggestion. Thank you.

Directed Mesh, check tutorial, if you need it send me your email address. Also check you-tube tutorial for pipe flow.

[Tasneem]

Dear me3840 and Saima,

Thank you so much for your help. I managed to get what I want using Directed Mesh as suggested. However, when I changed my mesh from my previous mesh which used Trimmer Mesh with prism layer to Directed Mesh with uniform spacing with one sided geometric near the wall, the solution does not converged as good as previous one.. By using trimmer mesh, the solution converged until E-7. However, by using new mesh, it converged until E-3 only. I tried to refine the mesh but the residual was still at the same range of value. I am decreasing the under relaxation factor for Velocity and Pressure from default value and still waiting for the outcome.

Do you have any idea of how to decrese the residual value?

I really apprecient your help.
Thank you.