Fluent's MSH grid learning

Research needs , Study Fluent The grid of msh Format .

A grid is set as shown in the figure above , It's a 1x9 Box domain , There are... Per unit length 5 A little bit ,4 individual , common 210 Points and 164 individual .

Output msh File format ,fluent The output is unstructured mesh , If it is 2 Wei's words , It consists of a series of points and lines , Each line and body has a specific topological relationship .

1. start

Turn on the output of msh file , The first two lines :

(0 " Created by : Fluent_V6 Interface Vers. 19.5.0")
(2 2)

0 Is the label of the annotation type , No specific meaning , It is convenient for the operator to read .2 Is the label of the grid dimension ,(2,2) Indicates that this line indicates the grid dimension , hinder 2 Indicates that the grid is 2 A grid of dimensions .

2. Point set node

(0 "Node Section")
(10 (0 1 d2 0 2))
(10 (a 1 d2 1 2)
(
0 0
0.0012499999751647284 0
0 0.0012499999720603228
0.0012499999751647275 0.0012500000000000005
0 0.0024999999441206455
0.0012499999751647264 0.0025000000000000005
0 0.0037499999161809683
0.0012499999751647251 0.0037500000000000003
0 0.004999999888241291
0.0012499999751647245 0.0050000000000000001
0.0024999999503294568 0
0.0024999999503294568 0.0012500000000000002
0.0024999999503294559 0.0025000000000000005
0.002499999950329455 0.0037500000000000007
...
))

Again , The first line is labeled 0 The following is the comment , The second line is labeled 10 Represents node data . Follow the format (10 (zone-id first-index last-index type ND)(x1 y1 z1  x2 y2 z2... )). Reference resources Fluent mesh Brief description of file format - pulse 96 - Blog Garden You know type There are many kinds of . If zone-id=0, first-index It will be 1,last-index Equal to the number of nodes （d2 Namely 210）,type Set to 0, ND Is the grid dimension , Coordinate data is not followed . If zone-id Greater than 0, Then, it represents the... In the structure nodes Belongs to number zone-id Of zone Area . here first-index and last-index For the sake of zone Node number of the area ,type Set to 1,ND Is an optional parameter , Represents the grid dimension . When ND=2 when , Node data is not displayed z coordinate . Because it's just one zone, So the second and third lines index It's the same .

3. Volume set cell

(12 (0 1 a4 0 0))
(12 (b 1 a4 1 3))

After the point set, the next two lines are labeled 12 Representative body set .a4 Namely 164 That is, the number of voxels in this grid . Look at the picture below , What follows is 3 Represents tetrahedron type .

  There was no answer cell The data of , Estimate is to generate a from 1 To a4 Array of .

4. Face set faced

(13 (0 1 175 0 0))
(0 "Interior faces of zone FLUID")
(13 (c 1 11b 2 2)(
2 4 1 5
4 3 1 2
4 6 2 6
6 5 2 3
6 8 3 7
8 7 3 4
8 a 4 8
b c 5 9
c 4 5 6
c d 6 a
d 6 6 7
d e 7 b
e 8 7 8
...
))

13 Is the label of the face . The first line is always , share 175（373） line （ Noodles ）, The following is the information of each part . Noodles （ Line ） There is an internal surface （ Line ） And boundaries . What's given above is interior Inner face , share 11b（283） strip . Look at the third line , The fourth one 2 Express interior, the last one 2 Indicates a linear type .

Four numbers in each subsequent line represent （ spot 1, spot 2, Left voxel , Right voxel ）. See the first line 2 4 1 5

  That is to say , At point 2 Sum point 4 A line connected , The body on the left is 1, The body on the right is 5. Why the front cell I didn't give too much information ？ Because it can be defined here , Don't repeat the definition , Save a space . This line also tells us , What two points connect this line , At the same time, it also carries the position information related to voxels , It is necessary in a finite volume .

(0 "Faces of zone IN")
(13 (d 11c 11f 3 2)(
3 1 1 0
5 3 2 0
7 5 3 0
9 7 4 0
)

notice IN The boundary of the , Be careful , Its starting point is 11c, And above interior The end of the game is 11b, It's end to end .type yes 3, representative wall type . See that the last one on every line is 0, It means , The line of the boundary specifies that the right side is the calculation domain , On the left is the calculation field . So it's easy to calculate .