[rupak504]

Hello,

I am meshing a 3D pipe having length 200 mm and diameter 25 mm. I will be using this mesh for multiphase flow using VOF, hence i wish to have a aspect ratio close to 1 since it gives the best result. I have attached all the figures 1.png, 2.png,Attachment 85723

As you can see in the figures, min aspect ration is 1.324.png and maximum aspect ratio of 2.813.png, also you can find the regions of trouble in figures. I have used O-grid mesh and modified it with an offset value of 0.5. All the number of divisions of various edges are shown here in this figure 9.png. I have also given a spacing 1 of 1 mm with Ratio 1 equals to 1.1.

Any help would be highly appreciated

regards

[rupak504]

I played around with the number of divisions and O-grid offset, removed the boundary layers at the wall and now the min aspect ratio is 1 and a max of 1.6610.png. Is there any guideline/tips/algorithm to get the aspect ratio close to 1 based on the dimension of the cylinder.


regards

[alainislas]

Personally, I don't see any problem in having cells with aspect ratio >1, especially at the near wall region. Depending on your y+ values, you'll find it inevitable. It is common practice to have aspect ratios 5-10 (sometimes even more).

CFD solvers are more sensitive to non-orthogonal qualities, min angle, skewness and/or determinants.

[rupak504]

Originally Posted by alainislas

Personally, I don't see any problem in having cells with aspect ratio >1, especially at the near wall region. Depending on your y+ values, you'll find it inevitable. It is common practice to have aspect ratios 5-10 (sometimes even more).

CFD solvers are more sensitive to non-orthogonal qualities, min angle, skewness and/or determinants.

Yes, thank you, i guess your are right, i was getting too sensitive about aspect ratio meanwhile forgetting the near wall scenario.

[Stel]

It is virtually impossible to get a perfect 1.0 aspect ratio for all elements using an O-Grid strategy. A range within 1-3 is pretty OK though, even for VOF. Eventually, a mesh sensitivity test will let you know if the resulting grid is OK for your purposes.