Viewing Elmer results with gmsh?

[gsal]

Hi:

New to Elmer. Just did the first tutorial, Heat Equation. I tried the post-processor to view results and found it a bit awkward; the VTK-based processor seems a lot better but I was not able to dynamically move the clipping plane, also, the part was always hollow and couldn't visualize temperature internal to the part...is this how it is supposed to work?

Anyway, I have seen gmsh nice capabilities, too; is it possible to read an Elmer's result file into gmsh? I though gmsh was advertised as a post-processor.

Thanks

gsal

[raback]

Hi

Yes, ElmerPost is little bit oldish look. Still it has more features than the VTK based widget and is actually faster in rendring than VTK library. That said, you can save results in a number of formats using the auxiliary ResultOutputSolver (see Models Manual). I would personally recommed saving in binary VTU and visualizing with Paraview which includes all the tricks of the trade.

-Peter

[gsal]

o.k., here it is the section from the Models Manual:

Code: Select all

Solver solver id
Equation String "ResultOutput"
    The name of the equation. This is actually not much needed since there are no degrees of freedom
    associated with this solver.
Procedure File "ResultOutputSolve" "ResultOutputSolver"
    The name of the file and subroutine.
Output File Name File
    Specifies the name of the output file.
Output Format String
    This keyword the output format of choice. The choices are gid, gsmh, vtk, vtu, and dx.
Gid Format Logical
Gmsh Format Logical
Vtk Format Logical
Vtu Format Logical
Dx Format Logical
    The user may also use the above logical keywords to set which of the formats is saved. This
    has more flexibility in that there may be several formats that are saved simultaneously where the
    Output Format keyword may only be used to activate one solution type.
    
The following keywords related only to the GiD, Vtu and Gsmh formats. In the other formats all
available degrees of freedom are saved.

Scalar Field i String
    The scalar fields to be saved, for example Pressure. Note that the fields must be numbered
    continously starting from one.
Vector Field i String
    The vector fields to be saved, for example Velocity
Tensor Field i String
    The tensor fields to be saved. The rank of tensor fields should be 3 in 2D and 6 in 3D.
    
Sometimes when the variables need to be explicitely listed it may be difficult to know what the actual
available variables are. For this purpose there is the following keyword.

Show Variables Logical
    Show all the different variables on output as a list. Default is False.

But I don't quite understand how to use it...am I to add another Solver section? Or include it in the same one? What exactly is the syntax? It looks like the manual forgot to include the equal sign; also, I don't quite know how to specify the keywords that are supposed to be related to gmsh and vtu output format to specify which Scalar or Vector quantities to save in the file, etc. Would you be kind enough to include the exact code to include into the *.sif file? Or one of yours?

Here is part of my "Solver 1" so you see what the variables are. ( I guess I was working on the Laminar Flow exercise, not the Heat Equation).

Code: Select all

Solver 1
  Equation = Navier-Stokes
  Procedure = "FlowSolve" "FlowSolver"
  Variable = Flow Solution[Velocity:2 Pressure:1]
  Exec Solver = Always
  Stabilize = True
 .
 .
 .
End

I tried to include "something" that I thought to be correct, but I get the following error message:

Code: Select all

ELMER SOLVER (v 6.1) STARTED AT: 2011/02/25 16:03:57
MAIN:
MAIN: ==========================================
MAIN:  E L M E R  S O L V E R  S T A R T I N G
MAIN:  Library version: 6.1 (Rev: 5043)
MAIN: ==========================================
MAIN:
MAIN:
MAIN: -----------------------
MAIN: Reading Model ...
ERROR:: Model Input:
ERROR:: Model Input:  Unknown specifier: [true]
ERROR:: Model Input:  In section: [solver 1]
ERROR:: Model Input:  For property name:[vtu format]

Thank you very much.

gsal

[raback]

Hi

There are plenty of sif files in the $ELMERHOME/tests directory, for example. There you can see the general layout of a typical sif if you want to insert the data manyally. The Solver Manual also deals with the sif file. The Models Manual does not indeed include the '=' sign which may confuse at first. The ResultOutputSolver is also available in the GUI if you do not want to get your hands dirty on the CLI.

-Peter

[gsal]

Great, thanks. I did find the sample *.sif files and instances of alternative output formats.

The reason why I was not using the GUI is because I am trying the recipe from Mark Smith on using gmsh to produce a mesh for Elmer...in this case, the GUI does not like the generated file, but the Solver does...so, the *.sif file needs to be put together "by hand" ...sure, one can possibly generate most of it with a simpler model just for the case of getting started with the *.sif file and then fine tune to target the actual entities.

Anyway, thanks again.

gsal