Meshing
Start Gmsh and create the mesh with:
gmsh -3 t3a.geoThen let’s do the same for the second file:
gmsh -3 t3b.geoPossible output
Start Gmsh and create the mesh with:
Info : Running 'gmsh -3 t3a.geo' [Gmsh 4.0.4, 1 node, max. 1 thread]
Info : Started on Wed Nov 07 15:57:02 2018
Info : Reading 't3a.geo'...
Info : Reading 't1.geo'...
Info : Done reading 't1.geo'
Info : Done reading 't3a.geo'
Info : Meshing 1D...
Info : Meshing curve 1 (Line)
...
Info : Meshing curve 86 (extruded)
Info : Done meshing 1D (0 s)
Info : Meshing 2D...
Info : Meshing surface 1 (Plane, Delaunay)
...
Info : Meshing surface 92 (extruded)
Info : Done meshing 2D (0.078125 s)
Info : Meshing 3D...
Info : Meshing volume 1 (extruded)
Info : Meshing volume 2 (extruded)
Info : Meshing volume 3 (extruded)
Info : Meshing volume 4 (extruded)
Info : Done meshing 3D (0.140625 s)
Info : Optimizing 3D mesh...
Info : Done optimizing 3D mesh (0 s)
Info : 15570 vertices 33542 elements
Info : Writing 't3a.msh'...
Info : Done writing 't3a.msh'
Info : Stopped on Wed Nov 07 15:57:02 2018
You can now open t3a.msh and t3b.msh to view the difference:
t3a – with the Recombine command
t3b – without the Recombine command
As can be seen, there is a difference in the 3D mesh, where the Recombine command generates only one element between any polygon in the 2D mesh, resulting in prisms. Leaving out this command, results in smaller, tetrahedral elements.
This can also be seen in the number of elements produces, shown in the output of the mesh-command:
t3a: 15570 vertices 33542 elements
t3b: 15570 vertices 90994 elements
Copying mesh
Again, to make sure the mesh file will not be overwritten by the results, we copy and rename the files:
cp t3a.msh t3ad.mshand:
cp t3b.msh t3bd.mshConverting to dolfyn input
We now convert the mesh into *.cel, a *.vrt, a *.bnd, and optionally an *.inp file using gmsh2dolfyn, and selecting the correct file to convert, in our case: t3ad.
gmsh2dolfynand again for t3bd.
Possible output
Start gmsh2dolfyn converter with:
gmsh2dolfyn
Gmsh2Dolfyn: Converts a Gmsh mesh file to Dolfyn format.
Input must be in Gmsh version 2.0, 2.1, 2.2 or 4 ascii format.
Input Gmsh filename, excluding the .msh suffix
t3bd
Opening the Gmsh file
File t3bd.msh opened
Reading MeshFormat
MeshFormat: 4 0 8
Reading PhysicalNames
Name 2 -> S1
Name 3 -> S2
Name 1 -> Fluid
Entities
Entity 1 surface 2 S1
Entity 92 surface 3 S2
Entity 1 volume 1 Fluid
Entity 2 volume 1 Fluid
Entity 3 volume 1 Fluid
Entity 4 volume 1 Fluid
Physical entities found 6
Reading Nodes
Number of entity blocks: 81 Nodes: 15552
Creating the dolfyn .vrt file
File t3bd.vrt opened
Point 1 Node 1
Point 2 Node 1
Point 3 Node 1
Point 4 Node 1
Point 5 Node 1
Point 6 Node 1
Point 10 Node 1
Point 14 Node 1
Point 15 Node 1
Point 16 Node 1
Point 20 Node 1
Point 24 Node 1
Point 39 Node 1
Point 40 Node 1
Point 44 Node 1
Point 48 Node 1
Point 96 Node 1
Point 97 Node 1
Point 101 Node 1
Point 105 Node 1
Curve 1 Nodes 7
Curve 2 Nodes 23
Curve 3 Nodes 7
Curve 4 Nodes 23
Curve 6 Nodes 23
Curve 7 Nodes 7
Curve 8 Nodes 23
Curve 9 Nodes 7
Curve 11 Nodes 3
Curve 12 Nodes 3
Curve 16 Nodes 3
Curve 20 Nodes 3
Curve 28 Nodes 23
Curve 29 Nodes 7
Curve 30 Nodes 23
Curve 31 Nodes 7
Curve 33 Nodes 8
Curve 34 Nodes 8
Curve 38 Nodes 8
Curve 42 Nodes 8
Curve 50 Nodes 23
Curve 51 Nodes 7
Curve 52 Nodes 23
Curve 53 Nodes 7
Curve 55 Nodes 23
Curve 56 Nodes 23
Curve 60 Nodes 23
Curve 64 Nodes 23
Curve 72 Nodes 23
Curve 73 Nodes 7
Curve 74 Nodes 23
Curve 75 Nodes 7
Curve 77 Nodes 15
Curve 78 Nodes 15
Curve 82 Nodes 15
Curve 86 Nodes 15
Surface 1 Nodes 224
Surface 13 Nodes 69
Surface 17 Nodes 21
Surface 21 Nodes 69
Surface 25 Nodes 21
Surface 26 Nodes 224
Surface 35 Nodes 184
Surface 39 Nodes 56
Surface 43 Nodes 184
Surface 47 Nodes 56
Surface 48 Nodes 224
Surface 57 Nodes 529
Surface 61 Nodes 161
Surface 65 Nodes 529
Surface 69 Nodes 161
Surface 70 Nodes 224
Surface 79 Nodes 345
Surface 83 Nodes 105
Surface 87 Nodes 345
Surface 91 Nodes 105
Surface 92 Nodes 224
Volume 1 Nodes 672
Volume 2 Nodes 1792
Volume 3 Nodes 5152
Volume 4 Nodes 3360
Nodes written 15552
Total Gmsh elements to be read in: 82110
Creating the dolfyn .cel and .bnd files 14 23
File t3bd.cel opened
File t3bd.bnd opened
Element 1 Fluid Type 2 510
Element 92 S2 Type 2 510
Element 1 Fluid Type 4 6120
Element 2 Fluid Type 4 13770
Element 3 Fluid Type 4 36720
Element 4 Fluid Type 4 24480
Triangle boundaries: 1020
Tetrahedral cells: 81090
Writing the .inp file
File t3bd.inp opened
inp: 2 S1 T
inp: 3 S2 T
Done gmsh2dolfyn 2018
Running Pre-Processor
Now we will run the pre-processor.
dolgeo -s 1.0 -b t3adand
dolgeo -s 1.0 -b t3bdIf no options are given with the dolgeo command, you will be prompted for them. Fill in case name t3ad or t3bd, scaling factor of 1.0 (default) and bin as format of geometry file.
Possible output
The pre-processor is run with:
dolgeo -s 1.0 -b t3bd
Dolfyn PreProcessor
t3bd T T T F
Using command line arguments
Using t3bd as input
Opening vertex file
Initialise vertex list
. . .
Region ID: 2 => S1
Region ID: 3 => S2
Type 1 regions found: 2 3
WARNING: check inp-file
Using: 1.00000000 binary
Dump binary geometry file
Done
Running Simulation
Finaly we will run the dolfyn simulations.
dolfyn t3adand:
dolfyn t3bdIf no case name is inputted directly, you will be prompted. If so, enter case name t3ad and t3bd.
Possible output
The pre-processor is run with:
dolfyn t3ad
This is dolfyn version 0.608
Copyright(C) 2002-2016 Cyclone Fluid Dynamics BV
NL-5583 XM, Waalre, The Netherlands
see http://www.cyclone.nl and https://www.dolfyn.net
Using Sparsekit2 by Yousef Saad
(C) 2005, the Regents of the University of Minnesota
Modules with patches (C) 2004-2010 by B. Tuinstra
see http://www.home.zonnet.nl/bouke_1/dolfyn
Tecplot interface (tecplt.f90) (C) 2006-2012 by
S.B. Kuang, UNSW, Sydney, Australia
VTK interface updated (C) 2007 by J. Jacobs
Static boundary conditions (C) 2011 by J. JoJo
MKL contributions and suggestions by Runar
Using case: t3ad
Appending echo to file t3ad.txt
Calling dolfyn t3ad .dge
t3ad.dge binary
. . .
*** CONVERGENCE *** 7.71197723E-04
Opening restart file
File t3ad.rst
Restartfile 400 written
Writing VTK data file... t3ad.vtk
Done
Writing Full Gmsh file...
Done
Maximum change in PP: 7.76433590E-05 0.182830691 1.00000005E-03
Arrays cleaned up
Done t3ad
Bye!
That’s it! Now all the calculations have been carried out, we can start to analyze the output.