Premesh CAD quality

Fridrik · January 10, 2018, 07:52

I have made a mesh of a very complex structure, and by using snappyHexMesh.

In the process there was a lot of failed meshes, and wondered if anybody has some kind of measure of the premesh quality of a CAD file?

I have an idea to a way of quantify this:
This is the length of the smallest line divided by the length of the average line
$\bar{S}=\frac{min(l_i)}{\frac{1}{n}\sum^n_{i=1}(l_i)}$

vishnupc · January 13, 2018, 12:05

Hi Fridrik,

When you say a 'failure' I would like to specifically know how ? I have not used snappyHexMesh and wanted to know if there are specific criteria setup to know that a mesh is a good one ?

Not sure if this answers your question but qualitatively I feel that the CAD is a good one if it is :

a. Connected as per the requirements of the simulation being performed (Based on which the geometry can have 1-sided or even 3+ sided edges)
b. Ideally should not have self intersections and coincident faces.

The main issue I have faced is that most geometries must be 'connected' as intended. This can be a little difficult when you are preparing a complex geometry prior to meshing. Once you DO do this check, your meshing procedure and subsequent cleanup should be not too difficult.

G'Luck !

January 10, 2018, 07:52	Premesh CAD quality	#1
Fridrik Member Fridrik Magnusson Join Date: Aug 2017 Location: Denmark Posts: 34 Rep Power: 9	I have made a mesh of a very complex structure, and by using snappyHexMesh. In the process there was a lot of failed meshes, and wondered if anybody has some kind of measure of the premesh quality of a CAD file? I have an idea to a way of quantify this: This is the length of the smallest line divided by the length of the average line $\bar{S}=\frac{min(l_i)}{\frac{1}{n}\sum^n_{i=1}(l_i)}$

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January 13, 2018, 12:05		#2
vishnupc New Member Vishnu Join Date: Mar 2015 Posts: 3 Rep Power: 11	Hi Fridrik, When you say a 'failure' I would like to specifically know how ? I have not used snappyHexMesh and wanted to know if there are specific criteria setup to know that a mesh is a good one ? Not sure if this answers your question but qualitatively I feel that the CAD is a good one if it is : a. Connected as per the requirements of the simulation being performed (Based on which the geometry can have 1-sided or even 3+ sided edges) b. Ideally should not have self intersections and coincident faces. The main issue I have faced is that most geometries must be 'connected' as intended. This can be a little difficult when you are preparing a complex geometry prior to meshing. Once you DO do this check, your meshing procedure and subsequent cleanup should be not too difficult. G'Luck !