Difference between Unstructured and Structured Mesh

SriHarsha48 · September 17, 2017, 19:34

Hello,

Could some one explain me the difference between Unstructured and Structured mesh.

I am also posting an image below.Can someone have a look at it and explain why the given configuration is Structured/Unstructured mesh?

Thanks in Advance!

ashokac7 · September 18, 2017, 07:08

In unstructured grid the elements are arranged in arbitrary fashion wheres in structural grid all grid line pass through the domain. So structural mesh may not be possible for complex geometry.

ashokac7 · September 18, 2017, 07:09

Plz go through the attachments.

FMDenaro · September 18, 2017, 07:13

Quote:

Originally Posted by SriHarsha48

Hello,

Could some one explain me the difference between Unstructured and Structured mesh.

I am also posting an image below.Can someone have a look at it and explain why the given configuration is Structured/Unstructured mesh?

Thanks in Advance!

you can find the answer in similar posts

praveen · September 20, 2017, 00:06

I dont know if there is a universally accepted definition and maybe people will debate this.

Let us list what we usually mean by a structured mesh.

The grid lines correspond to coordinates directions, could be Cartesian or curvilinear.
There is a fixed topology throughout the mesh. E.g., each cell has four neighbours in 2d.
You can have simple indexing of cells, say (i,j) in 2d, which gives the connectivity of cells in an explicit way. There is a regular pattern of memory access to get neighbour information.

If these properties are not satisfied, then we can say the mesh is unstructured. In this sense, the AMR mesh would be unstructured since it does not satisfy any of the properties.

Note that even a structured mesh could be stored in an unstructured format, i.e., without using (i,j) indexing. So in another sense, it also depends on the data structures used to store the mesh.

piu58 · September 20, 2017, 01:09

From computational point, your mesh is not especially well structured:
1) There are "irregular" cells with 5 (instead of 4) control points
2) There are large steps in the cell size.

September 20, 2017, 00:06		#5
praveen Super Moderator Praveen. C Join Date: Mar 2009 Location: Bangalore Posts: 342 Blog Entries: 6 Rep Power: 18	I dont know if there is a universally accepted definition and maybe people will debate this. Let us list what we usually mean by a structured mesh. The grid lines correspond to coordinates directions, could be Cartesian or curvilinear. There is a fixed topology throughout the mesh. E.g., each cell has four neighbours in 2d. You can have simple indexing of cells, say (i,j) in 2d, which gives the connectivity of cells in an explicit way. There is a regular pattern of memory access to get neighbour information. If these properties are not satisfied, then we can say the mesh is unstructured. In this sense, the AMR mesh would be unstructured since it does not satisfy any of the properties. Note that even a structured mesh could be stored in an unstructured format, i.e., without using (i,j) indexing. So in another sense, it also depends on the data structures used to store the mesh. sbaffini and tiam like this. __________________ http://cpraveen.github.io http://twitter.com/cfdlab http://github.com/cpraveen

September 20, 2017, 01:09		#6
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	From computational point, your mesh is not especially well structured: 1) There are "irregular" cells with 5 (instead of 4) control points 2) There are large steps in the cell size. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

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September 18, 2017, 07:08		#2
ashokac7 Senior Member Ashok Chaudhari Join Date: Aug 2016 Location: Pune, India Posts: 260 Rep Power: 10	In unstructured grid the elements are arranged in arbitrary fashion wheres in structural grid all grid line pass through the domain. So structural mesh may not be possible for complex geometry.

September 18, 2017, 07:09		#3
ashokac7 Senior Member Ashok Chaudhari Join Date: Aug 2016 Location: Pune, India Posts: 260 Rep Power: 10	Plz go through the attachments.