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  3. Tutorial 3: Symmetry & Temperature
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Input Files

In this example we are going to use t4.geo, which we will edit slightly.

All alterations are mentioned below the sample code:

t4.geo

// until here, no changes

Curve Loop(21) = {17,-15,18,19,-20,16};
// Plane Surface(22) = {21};

Curve Loop(23) = {11,-12,13,14,1,2,-3,4,5,6,7,-8,9,10};
Plane Surface(24) = {23,21};
Recombine Surface{24};

View "comments" {
  T2(10, -10, 0) { StrCat("Created on ", Today, " - www.dolfyn.net") };

  T3(0, 0.11, 0, TextAttributes("Align", "Center", "Font", "Helvetica")){ "Hole" };

  // T3(0, 0.09, 0, TextAttributes("Align", "Center")){ "file://image.png@0.01x0" };

  // T3(-0.01, 0.09, 0, 0){ "file://image.png@0.01x0,0,0,1,0,1,0" };

  // T3(0, 0.12, 0, TextAttributes("Align", "Center")){ "file://image.png@0.01x0#" };

  // T2(350, -7, 0){ "file://image.png@20x0" };
};

View[0].DoubleClickedCommand = "Printf('View[0] has been double-clicked!');";
Geometry.DoubleClickedLineCommand = "Printf('Curve %g has been double-clicked!',
  Geometry.DoubleClickedEntityTag);";


Color Grey50{ Surface{ 22 }; }
Color Purple{ Surface{ 24 }; }
Color Red{ Curve{ 1:14 }; }
Color Yellow{ Curve{ 15:20 }; }

/* * * * * * * * * * * *
 * Dolfyn added lines: *
 * * * * * * * * * * * */

// Making a volume

Extrude {0,0,0.005} {Surface{24}; Layers{1}; Recombine; }

// Boundaries (non-default)

Physical Volume("Fluid")  =   {1};
Physical Surface("Swall") =  {57,53,49,101,97,93,89,81,77,73,69,65};
Physical Surface("SwallHole") =  {121,125,105,109,113,117};
Physical Surface("Sin")   =  {61};
Physical Surface("Sout")  =  {85};
Physical Surface("Ssym1") =  {24};
Physical Surface("Ssym2") = {126};

Note

We edited the following (line numbers according to original document):

  • line 66 – We don’t need this surface. We’ll define it when the hole is defined
  • line 73 – Recombine the created surface to generate a different mesh
  • Commented out lines:
    • line 94, 98, 102, 105 – inserting pictures is not important
  • Added lines (important!):
    • line 121-127 – Added an extrude to create a volume
    • line 128-136 – defined a new Physical Volume and Physical Surfaces for an In- and Outlet.

Visually the model will look like this:

Lastly, the t4d.din file.

> See the DINGuide (on the Downloads page) for reference.

t4d.din

title Test Gmsh t4.geo model
#restart init
steps 600 1.e-4

output, every, 5

set T0 273.0
set T1 $T0 + 10.0
set T2 $T0 + 20.0
limit t lower $T0
limit t upper $T2

opendx off
use gmsh  fluid
use vtk
#aluminium
density,2.7
conductivity,237
vislam 20.e-6

transient, 0.01

relax 0.7 0.3 0.7
#turbulence ke 0.001
thermal on
init,field,0.0 0.0 0.0,,1.e-4,1.e-4,$T0
init steps 0
gravity 0 0 0

scheme UVW  LUX 0.8
scheme KEPS LUD 0.8
scheme T    LUD 0.9

slope UVW  vnf
slope P    vnf
slope KEPS vnf

#post p   vert
#post k   vert

#post k   cell
#post eps cell
#post vis cell
post T   cell
post T   vert

boundary,swall
wall
noslip
0.0 0.0 0.0
adiabatic

boundary,swallhole
wall
noslip
0.0 0.0 0.0
adiabatic

boundary,sin
wall
noslip
0.0 0.0 0.0
fixed
$T1 0.0

boundary,sout
wall
noslip
0.0 0.0 0.0
fixed
$T2 0.0

boundary,ssym1
symp

boundary,ssym2
symp

Again use gmsh fluid is used (line 8), to produce a full *.msh file, but ommitting the results on the boudaries.

Moreover, this time we added 2 symmetry planes.

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