Table of Contents

Post-treatments

This page present some information regarding the post-treatment of results.

ElmerPost

ElmerPost is the build-in post-processing tools of Elmer. ElmerPost reads result in Elmer Post type file (.ep).

Mesh deformation

For transient simulation, ElmerPost doesn't upgrade directly the mesh using the variable Mesh Update. This has to be done manually, as follow. First define a new variable to store the initial node coordinates. Enter in the command window (bottom of the main window):

math on = nodes

Then, in the command box of the timestep window:

math nodes = on + Mesh.Update(0:2,time($t)))

Useful scripts

A file containing a matc function can be loaded and executed from the command window:

source myscript.cmd
myMATCfunction

Below is an example to construct a vector variable from 3 independent variable (useful for the AIFlow and Porous solvers):

proc tovector {} {
math {Velocity=0};
math {k=size(Aiflow.1)[1];}
math {Velocity(0,0:k-1)=Aiflow.1};
math {Velocity(1,0:k-1)=Aiflow.2};
math {Velocity(2,0:k-1)=0};
math {Velocity_abs=sqrt(vdot(Velocity,Velocity))};
}

Save it in a file makeVector.cmd and execute it as follow:

load makeVector.cmd
tovector

ParaView

Elmer can export results in vtk or vtu formats. Since version 6128, this can be done automatically by setting the extension of the Post File to vtu in the Simulation section. Doing so, only a vtu output file is created (no ep file for ElmerPost). Alternatively, the following solver can be added and run after all other solvers:

Solver 17
  Exec Solver = After TimeStep
  Exec Interval = 2
  Equation = "result output"
  Procedure = "ResultOutputSolve" "ResultOutputSolver"
  Save Geometry Ids = Logical True ! add this line if you want to access boundaries in Paraview
  Output File Name = String "myFile.vtu"
  Output Format = String vtu
End

More information regarding this solver can be found in the Elmer documentation. More information regarding the Paraview software can be found here.

Some tips when using Paraview:

  • to visualize a variable only on one boundary condition (for example bedrock):

- Add the line Save Geometry Ids = Logical True to your sif-file
- In paraview: Edit → Find Data, find Cell, GeometryIDs is = …, Run Extract Selection
- GeometryIDs usually start from 101

  • to calculate differences between different time-steps or runs (condition: same mesh)

- Open both files
- Define for both files a Calculator to copy the variables that you want to calculate the difference from under another name, for example Result ArrayName = temp1 (temp2) for Value = Scalars→ temp
- Select both Calculators: Filters → Append Attributes
- Select the new AppendAttributes Item in the list (the one with the cube not the arrows)
- Define again a Calculator with Result ArrayName=difftemp and Value= Scalars→temp2 - Scalars→temp1
- difftemp contains now the difference

  • to mark a certain location by a symbol

- use Sources → Sphere and define the origin as the location of your symbol

  • to add a polyline on a 3D figure

- save the (x,y,z) values of the points of the polyline in an ascii file (separated by “,” or another symbol) with the ending “.csv”
- open this file as “comma separated values”-file in paraview
- define the options (with headings or not etc.)
- use TableToPoints Filter

  • Crossections of the ice-body

- use “Slice” or “Clip”

  • do not use ° in any text, this leads to errors when saving/loading a statefile.

If it has happened, open the statefile as ascii file and delete the ° and it should work again.

  • Iso-contours

To draw only the lines, but not colored areas, switch “Compute Normals off”, that helps in most of the cases.

  • to synchronize the view on different windows (same zoom, view angle,…)

- click right on the first window
- click on link camera
- once the window click on another window appears click on the second window“

tips/post.txt · Last modified: 2013/06/27 18:57 by mschafer
CC Attribution-Share Alike 4.0 International
www.chimeric.de Valid CSS Driven by DokuWiki do yourself a favour and use a real browser - get firefox!! Recent changes RSS feed Valid XHTML 1.0