PATC FEM GMSH-GUI-VTU example … · PATC FEM – GMSH-GUI-VTU example ... GMSH Circle Arc Select the upper middle point as start point ... Elmer, ElmerGUI, Tutorial, FEM

8/20/2012

1

PATC FEM – GMSH-GUI-VTU example

Cooling of steel block by periodic

pipes

A walk-through demonstration

8/20/2012

2

Work Flow

GMSH

VTU

Work Flow

Pre-processing Create a bottom-up geometry in GMSH

Meshing in GMSH

Use ElmerGrid to create Elmer mesh

Set-up Importing mesh into ElmerGUI

Defining the case/project

Run

Post-processing Using ElmerPost

Adding Result Output Solver to export VTU for ParaView

8/20/2012

3

Pre-Processing: GMSH

Create a new sub-directory: mkdir name

Change into this directory: cd name

Launch GMSH: gmsh periodic.geo Elementary entities

Add

New

Point


8/20/2012

4


Start with point (0,0,0)

Prescribed mesh element

size at point: 0.1 (see

previous slide)

Add points:

(0,1,0), (1,1,0) and (1,0,0)

Straight Line

– Klick on two adjacent points

– 4 times to create a closed

square

Add further two Points:

(0.5,0.5,0) and (0.5,0.7,0)


Circle Arc

Select the upper middle

point as start point

Select the middle point as

centre point

Select again the upper

middle point as end point

If you get a red warning in

the communication window:

ignore it

8/20/2012

5


Plane surface

Select all 4 straight lines by

clicking on them

Select circle as the hole

boundary

Finally, press e


Plane surface

Select circle

Finally, press e

8/20/2012

6


Geometry (click into

blue array)

Elementary entities

Extrude

Surface

Set 1 for Z

component

Click on both

surfaces (cross lines

should turn red)

Finally, press e

// the square

Point(1) = {0, 0, 0, 0.1};

Point(2) = {0, 1, 0, 0.1};

Point(3) = {1, 1, 0, 0.1};

Point(4) = {1, 0, 0, 0.1};

Line(1) = {1, 4};

Line(2) = {4, 3};

Line(3) = {3, 2};

Line(4) = {2, 1};

// the circle in the centre

Point(5) = {0.5, 0.5, 0, 0.1};

Point(6) = {0.5, 0.7, 0, 0.1};

Circle(5) = {6, 5, 6};

// creating the surfaces

Line Loop(6) = {2, 3, 4, 1};

Line Loop(7) = {5};

Plane Surface(8) = {6, 7};

Plane Surface(9) = {7};

//extruding them

Extrude {0, 0, 1} {

Surface{9, 8}; Layers{10};

}


Before continuing, open the

file periodic.geo using a

text editor (emacs)

Add Layers{10}; to the

extrusion command line

Save and close

Re-open in GMSH by

clicking on

Geometry

Reload NB: the comment lines in the example right won’t

show in your case

8/20/2012

7


Mesh

3D

The mesh should

appear after a

while

A summary of the

meshing procedure

is reported in the

text window


Geometry

Physical Groups

Add

Volumes

Click on the part in the middle

(pipe; should turn red)

Press e

Click on the outer part (block;

should turn red)

Press e

Now, do yourself a favor and

reload the case once again

(to get rid of the mesh)

8/20/2012

8


Geometry

Physical Groups

Add

Surface

Click in the

annotated order on

the boundaries

(always one at a

time) and press e 1. Inflow

2. Outflow

3. Block at inflow

4. Block at outflow

5. Pipe wall

6. - 9. Block sides

2

1

4

5

3

6

7

9

8


Sorry, but once

again now:

Mesh

3D

The mesh should

appear after a

while

A summary of the

meshing procedure

is reported in the

text window

Save the mesh

In your terminal:

ElmerGrid 14 2 periodic.msh -autoclean

8/20/2012

9

Pre-Processing: GMSH ElmerGrid 14 3 periodic.msh –autoclean

ElmerPost :File →Open periodic.ep

Edit →Grouping

Pre-Processing: Simulation set-up

Body 1 (pipe): oil

Body 2 (block): steel

BC’s: 1 Inflow: pext = -0.1

2 Outflow

3+4 adiabatic

5 pipe wall (no slip)

6 →7 periodic

8 fixed temperature T = 30 C

9 fixed heat flux q=200 W/m2

104.49

8/20/2012

10

Pre-Processing: ElmerGUI

Launch

ElmerGUI in terminal:

ElmerGUI

File

Load mesh

periodic


Model

Setup…

Just press

Apply

8/20/2012

11


To identify the

body number:

– View

– Numbering

– Body Index

To hide of

certain surface:

– Double click on

surface

– Surface turns

red

– Press Ctrl + H


Model

Equation

Go to tab Heat Equation

– Toggle Active

– Priority:1

– Toggle Body 1

Edit Solver Setting

– General: Toggle Stabilize

– Nonlinear System: Max.

iterations 1

– Apply

8/20/2012

12


Go to tab Navier Stokes

– Toggle Active

– Priority:2

Edit Solver Setting

– General: Toggle Stabilize

– Apply

To open a new equation:

– Add

– New (new window for

Equation 2 opens)

– OK (in the previous window

to close it)


All setting for Solvers

remain, but we have to

take off the Navier Stokes

solver


– Toggle off Active

8/20/2012

13


Model

Material

– Toggle Body 1

Material Library

– Choose Oil, olive

– Apply (library window

closes)

– Add

– New (new window opens)

– OK (close old window)

Similar for second:

– Toggle Body 2

– Material library: Steel

– Apply

– OK (close old window)


To identify the

body number:

– View

– Numbering

– Boundary Index

8/20/2012

14


Model

Boundary Condition Add

– Name: inflow

Go to tab General

– Toggle Boundary 1

– Velocity 1 and 2: 0

– External Pressure: -0.1


– Temperature: 10

OK


Model




– Toggle Use normal-tangential …

– Velocity 2 and 3: 0 (only normal

outflow)

– Name: outflow

OK

8/20/2012

15


Model


– Name: Adiabatic walls

Go to tab General

– Toggle Boundary 3 and 4

(collecting the two

boundaries into one)

OK


Model


– Name: periodic target

Go to tab General


– Periodic Boundary ID 7

(links variable values

of boundary 6 to

boundary 7)

OK

8/20/2012

16


Model


– Name: periodic source


OK


Model


– Name: Fixed Temperature



– Temperature: 30

OK

8/20/2012

17


Model


– Name: Fixed Heat Flux



– Heat Flux: 200.0

OK


That’s it! Only almost, though.

Sif

Generate

Save Current Project:

– You can make a new directory by clicking on Create Folder

– Open

Save the files:

Once again, save Current Project:

– Open

OK

8/20/2012

18

Run

Run the case:

– Either Run→start solver or

– The symbol then will change color

– A log window will occur

– And a convergence graph

– Ready, when

Post-processing

Two post processors:

1. Internal VTK based:

Run →

Postprocessor (VTK)

2. Externally linked

ElmerPost (legacy

postprocessor of

Elmer): – Either Run → Start

postprocessor or

– Changes color if

active

8/20/2012

19

Post-processing

We want to use external

postprocessor ParaView

To that end, we add another

solver to both, Equation 1

and 2

Model

Equation: Equation 1

Change to tab Result output

– Toggle Active

– Toggle Body 1

– Edit Solver Settings

Post-processing

Change to tab General:

– Toggle After Simulation

Change to tab Solver

Specific options:

– Output Format: Vtu

– Toggle Binary Output

– Toggle Save Geometry Ids

– Output File Name: caseVTU

– Scalar Field 1: Temperature

– Vector Field 1: Velocity

– Apply

Redo the whole saving

procedure

– Sif, Generate, ,

– Re-run:

http://www.paraview.org/

8/20/2012

20

Post-processing

Launch ParaView in your terminal: paraview – File, Open: choose casevtu0001.vtu

Documents

PATC FEM GMSH-GUI-VTU example … · PATC FEM – GMSH-GUI-VTU example ... GMSH Circle Arc Select the upper middle point as start point ... Elmer, ElmerGUI, Tutorial, FEM