CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Special Topics > Mesh Generation & Pre-Processing

Gmsh format Version 4

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 4, 2018, 02:14
Default Gmsh format Version 4
  #1
New Member
 
Juan
Join Date: Sep 2018
Posts: 1
Rep Power: 0
wideli is on a distinguished road
I am completely new to the finite element/ finite volume modeling. I have some problems to understand the 'tags' of the .msh file. Hope someone can help me understand it.

I use Gmsh to define the domain for computation and to generate unstructured mesh. I further partition the mesh into several subdomains using the embedded functionality (Metis). Shown in the bottom is the complete .msh file, where the mesh is divided into 5 partitions.

Could someone explain me each of the tag associated with the element? For example, the output info of the 68th, 70th and 71st element is:

68 4 7 0 16 4 5 -2 -3 -4 12 11 1 7
70 4 8 0 16 5 4 -1 -2 -3 -5 13 8 12 1
71 4 8 0 16 5 5 -1 -2 -3 -4 13 12 11 1

The 1st integer of each row, 68/70/71, is the ordering of the element.
The 2nd integer, 4, is the element type, where the integer, 4, stands for the tetrahedron type.

The last 4 integers are the list of the vertex of each element, e.g., 12-11-1-7, 13-8-12-1 and 13-12-11-1 for the 68th, 70th and 71st element, respectively.

I do NOT understand the rest of the tags. The Gmsh manual does clarify these.

1. What do the 3rd to the 5th integers stand for, e.g., 7-0-16, 8-0-16 and 8-0-16 for the 68th, 70th and 71st element? And why, for the same type of element, the 1st integer of the lists, 7-0-16, 8-0-16 and 8-0-16, is different for different element?

2. The rest of tags, 4-5-(-2)-(-3)-(-4), 5-4-(-1)-(-2)-(-3)-(-5) and 5-5-(-1)-(-2)-(-3)-(-4), seem to be the information of partitioning. What does the 1st integer of the lists shown above stand for? And why, for different element, this number could be different? The 2nd one seems to be the partition-number. The negative integers are the ghost points, which is shared with the other elements belonging to different partitions.

Hope someone can guide me through it. Many many thanks in advance!

Juan


$MeshFormat
2.2 0 8
$EndMeshFormat
$Nodes
13
1 0 0 0
2 1 0 0
3 0 1 0
4 0 0 1
5 0.4999999999983151 0.5000000000016849 0
6 0.5000000000016849 0 0.4999999999983151
7 0 0 0.5000000000020587
8 0.4999999999986943 0 0
9 0 0.4999999999986943 0
10 0 0.5000000000016849 0.4999999999983151
11 0 0.2500000000000948 0.2500000000000934
12 0.2500000000000948 0 0.2500000000000934
13 0.2499999999992523 0.2500000000000948 0
$EndNodes
$Elements
71
1 15 2 0 -2 6
2 15 2 0 -1 13
3 15 2 0 1 1
4 15 2 0 2 2
5 15 2 0 3 3
6 15 2 0 4 4
7 1 2 0 -4 11 13
8 1 2 0 -3 10 13
9 1 2 0 -2 13 6
10 1 2 0 -1 6 11
11 1 2 0 1 3 5
12 1 2 0 1 5 2
13 1 2 0 2 2 6
14 1 2 0 2 6 4
15 1 2 0 3 4 7
16 1 2 0 3 7 1
17 1 2 0 4 1 8
18 1 2 0 4 8 2
19 1 2 0 5 1 9
20 1 2 0 5 9 3
21 1 2 0 6 3 10
22 1 2 0 6 10 4
23 2 2 0 -8 10 13 11
24 2 2 0 -7 13 11 9
25 2 2 0 -6 6 13 11
26 2 2 0 -5 10 6 13
27 2 2 0 -4 8 13 6
28 2 2 0 -3 6 11 7
29 2 2 0 -2 13 10 5
30 2 2 0 -1 1 13 11
31 2 2 0 -1 13 5 6
32 2 2 0 -1 6 11 7
33 2 2 0 -1 6 13 11
34 2 4 0 8 1 5 7 1 11
35 2 4 0 8 1 5 11 1 9
36 2 4 0 8 1 2 10 9 3
37 2 4 0 8 1 3 4 7 10
38 2 4 0 8 1 3 10 7 11
39 2 4 0 8 1 2 11 9 10
40 2 4 0 10 1 5 1 12 7
41 2 4 0 10 1 4 1 8 12
42 2 4 0 10 1 1 2 6 8
43 2 4 0 10 1 3 6 4 7
44 2 4 0 10 1 5 6 7 12
45 2 4 0 10 1 4 6 12 8
46 2 4 0 12 1 4 13 8 1
47 2 4 0 12 1 5 9 13 1
48 2 4 0 12 1 1 2 8 5
49 2 4 0 12 1 2 5 9 3
50 2 4 0 12 1 1 8 13 5
51 2 4 0 12 1 2 13 9 5
52 2 4 0 14 1 1 2 6 5
53 2 4 0 14 1 2 5 10 3
54 2 4 0 14 1 3 6 4 10
55 2 4 0 14 1 1 6 10 5
56 4 8 0 16 5 4 -1 -2 -3 -5 6 11 13 12
57 4 8 0 16 5 3 -1 -2 -4 -5 10 13 6 11
58 4 8 0 16 5 5 -1 -3 -4 -2 12 11 7 6
59 4 8 0 16 5 4 -1 -2 -3 -5 8 13 12 6
60 4 8 0 16 5 2 -1 -3 -4 -5 13 9 11 10
61 4 8 0 16 5 1 -2 -3 -4 -5 13 10 6 5
62 4 8 0 16 5 3 -1 -2 -4 -5 7 10 4 6
63 4 8 0 16 5 1 -2 -3 -4 -5 5 8 2 6
64 4 7 0 16 4 2 -1 -3 -5 9 3 10 5
65 4 8 0 16 5 3 -1 -2 -4 -5 11 10 7 6
66 4 8 0 16 5 1 -2 -3 -4 -5 13 8 5 6
67 4 8 0 16 5 2 -1 -3 -4 -5 13 9 10 5
68 4 7 0 16 4 5 -2 -3 -4 12 11 1 7
69 4 8 0 16 5 5 -1 -2 -3 -4 9 13 11 1
70 4 8 0 16 5 4 -1 -2 -3 -5 13 8 12 1
71 4 8 0 16 5 5 -1 -2 -3 -4 13 12 11 1
$EndElements
wideli is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Periodic cyclic AMI + MRF crashing on pressure Swift OpenFOAM Running, Solving & CFD 8 May 17, 2019 02:55
[Gmsh] Version 20 of the bmshb file format to FOAM converter 7islands OpenFOAM Meshing & Mesh Conversion 36 February 9, 2019 23:47
DPMFoam - Serious Error --particle-laden flow in simple geometric config benz25 OpenFOAM Running, Solving & CFD 27 December 19, 2017 21:47
simpleFoam - wrong results? Zibi OpenFOAM Running, Solving & CFD 25 October 25, 2017 06:50
oopenFoam error cyndy M OpenFOAM Pre-Processing 7 March 30, 2016 09:03


All times are GMT -4. The time now is 19:01.