[Paraview] Degrees of freedom

Wed Nov 22 05:04:55 EST 2017

Hi Samuel,

Thank you so much! This is extremely helpful ^_^

________________________________
From: Samuel Key <samuelkey at bresnan.net>
Sent: November 21, 2017 10:38:15 PM
To: Doina Gumeniuc (224252 MAHS); paraview at paraview.org
Subject: Re: [Paraview] Degrees of freedom

Doina--

In what follows, I will skip talking about a 3-nod quadratic line as a way to display a cured beam or a deformed beam. (I live in a world of large deformation simulations and I like to display that type of behavior.)

The concept of FIELD (aka GLOBAL) simulation results, for example, results that come from or related to overall behavior like total Kinetic Energy (KE), are well supported by the Exodus-II format and are absent from the EnSight format and the VTK format for simulation results. I will confine my comments to what I have to offer to just POINT data and CELL data.

It is convenient to divide simulation results into three categories for virtually all of the data formats that PV can read.

(1) GEOMETRY data

(2) POINT data

(3) CELL data

The following is the VTK-XML ASCII format. (See the attached file 'resultsvtk.f')

(1) GEOMETRY. ParaView is quite happy with just GEOMETRY data.(It is a nice way to start when one is trying to write a datum set for ParaView. ParaView will display an object with only the geometry data.)

(1a) Write the entire Point inventory from 1 to n where n = number of nodal points  in terms of coordinate 3-tuples [(x1,y1,z1,), ...,(xn,yn,zn)]

(1b) Write the entire Cell inventory of connectivity n-tuples (as array offsets!)

(1c) Write the 'starting location' for the n-tuples in (1b)

(1d) Write the VTK cell-type values for the n-tuples in (1b)

ParaView now has everything it needs to display your geometry.

(2) Write POINT data information.

(2a) In the case of 'mode shapes,' write the mode's displacement 3-tuples (aka Vectors, name="Mode1")

[(UxM1,UyM1,UzM1),...,(UxMn,UyMn,UzMn)]

(2b) Repeat with name="Mode2", and so fourth (aka und so weiter)

ParaView now has the enough information to animate the mode shapes. Instructions are here

( https://public.kitware.com/pipermail/paraview/2017-October/041077.html ) for producing animations of the mode shapes.

Hope this helps.

--Sam

On 11/21/2017 7:15 AM, Doina Gumeniuc (224252 MAHS) wrote:

Hi Samuel,

Thank you for your reply.

I have different frequencies, 50 in total. If I use FIELD POINT DATA and then for arrayname 1 and so on, I use the Freq1, Freq2... then for 6Dofs, I use vectors in x,y,z for translation and Phi-x,Phi-y, Phi-z for rotation.... would it make sense in paraview? I can hopefully then warp by vectors using the data for each frequency.

Thank you! I hope I was clear.

________________________________
From: ParaView <paraview-bounces at paraview.org><mailto:paraview-bounces at paraview.org> on behalf of Samuel Key <samuelkey at bresnan.net><mailto:samuelkey at bresnan.net>
Sent: November 18, 2017 7:00:51 PM
To: paraview at paraview.org<mailto:paraview at paraview.org>
Subject: Re: [Paraview] Degrees of freedom

Doina--

At the risk of underestimating ParaView's functionalities, I can tell you what will work. For displaying geometry,  PV only needs Point (aka nodal point) x,y,z-coordinates, a Cell (aka Finite Element, ...)  type  and for each Cell an n-tuple of Point "array locations", for example, EnSight-format::{1,2,4,3,7,8,} or VTK-format::{0,1,3,2,6,7}.

The VTK format uses C-language 'array offsets' for Cell connectivity n-tuples. The EnSight format uses FORTRAN-language array locations for Finite Element connectivity n-tuples. It is just the way it is.

Variables are either located at Points or in Cells (conceptually Cell centers). The arrays supplied for variables must span all of the Points or all of the Cells. (I do not know how to use or about the acceptability of "partially" specified variable datum sets.) For Points with 6-DOFs versus 3-DOFs, if you want to see the three rotational DOFs, use POINT DATA arrays and fill in the Phi-x, Phi-y, Phi-z values using zeros for at those Points without a rotation.

If you want to visually display a 2-node, 6-DOF beam's geometry (a curved beam or a deformed beam) , one solution is too use a VTK Cell type 'VTK_QUADRATIC_EDGE = 21'  for the beam. This will require you to add-on-the-fly to the simulation results a beam center-Point with x,y,z-coordinates and displacements for the beam's center Point using the beam's interpolation functions. (PV has a Warp Filter that will let you then scale up the deflections for visualization purposes.)

Should you have access to source code for the simulations, I can supply FORTRAN language routines that write VTK ASCII-formatted simulation results. (My personal preference is the EnSight format.)

--Sam

On 11/18/2017 6:12 AM, Doina Gumeniuc (224252 MAHS) wrote:

Hi all!

I am still learning the use of paraview and I have got to such a question: How to show in a vtk input file the degrees of freedom of elements? Some of the beams have 6 degrees of freedom, some of the other elements...less or nothing at all. IS there any possibility?

Thank you a lot in advance!

_______________________________________________
Powered by www.kitware.com<http://www.kitware.com>

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Please keep messages on-topic and check the ParaView Wiki at: http://paraview.org/Wiki/ParaView

Search the list archives at: http://markmail.org/search/?q=ParaView

Follow this link to subscribe/unsubscribe:
http://public.kitware.com/mailman/listinfo/paraview

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/paraview/attachments/20171122/93c326b8/attachment.html>