CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Community Contributions > OpenFOAM CC Toolkits for Fluid-Structure Interaction

[solids4Foam] Physical damping for the solid in solids4Foam

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree4Likes
  • 1 Post By evxta3
  • 1 Post By bigphil
  • 2 Post By bigphil

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 9, 2020, 04:07
Default Physical damping for the solid in solids4Foam
  #1
New Member
 
Tommaso
Join Date: Jan 2020
Posts: 4
Rep Power: 2
evxta3 is on a distinguished road
Dear all,

Iím currently investigating wave loading on flexible structures with solids4foam.
I was wondering if in the solid model/solution is included any kind of damping coefficient or effect. Iím using a linearElastic consitutive law and a
linearGeometryTotalDisplacement solid model.


Thanks,
Tommaso
evxta3 is offline   Reply With Quote

Old   June 9, 2020, 04:10
Default
  #2
New Member
 
Tommaso
Join Date: Jan 2020
Posts: 4
Rep Power: 2
evxta3 is on a distinguished road
By default, there is no physical damping included.

Depending on the temporal discretisation, however, numerical damping may be significant. For example, 1st order Euler typically requires very small time-steps to keep numerical damping small.

I am now wondering if the numerical damping may depend also on other factors, for example the spatial discretisation or the mechanical properties of the structure (e.g. mass, sfiffness..).
bigphil likes this.
evxta3 is offline   Reply With Quote

Old   June 9, 2020, 05:35
Default
  #3
Super Moderator
 
bigphil's Avatar
 
Philip Cardiff
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 835
Rep Power: 28
bigphil will become famous soon enoughbigphil will become famous soon enough
Quote:
Originally Posted by evxta3 View Post
I am now wondering if the numerical damping may depend also on other factors, for example the spatial discretisation or the mechanical properties of the structure (e.g. mass, sfiffness..).
Primarily numerical damping for transient-dominant cases comes for temporal discretisation.

There are, however, other types of numerical damping, like spatial damping (spatial smoothing of the solution). For example, the Rhie-Chow smoothing term does this and in some cases it may be too large (particularly for elasto-plastic analyses, it may need to be scaled). The spatial discretisation in general will also contributed.

I guess the easiest way to check for your case is to try out different settings.

Philip
Daniel_Khazaei likes this.
bigphil is offline   Reply With Quote

Old   June 10, 2020, 04:53
Default
  #4
New Member
 
Tommaso
Join Date: Jan 2020
Posts: 4
Rep Power: 2
evxta3 is on a distinguished road
Hi all,

Iím trying to use a dynamic mesh for the solid to see if it also has a certain effect on the final displacements.

I modified constant/solid/dynamicMeshDict:

dynamicFvMesh dynamicMotionSolverFvMesh;

solver displacementSBRStress;

diffusivity quadratic inverseDistance (interface);

frozenDiffusion off;
distancePatches
(
interface
);

And I included pointDisplacement in 0/solid and the celldisplacement solver in system/solid/fvSolution.
The code runs without any errors.
However, the mesh of the solid still looks static and actually pointDisplacements are zero during the simulations, so it seems they are not solved.
evxta3 is offline   Reply With Quote

Old   June 10, 2020, 06:39
Default
  #5
Super Moderator
 
bigphil's Avatar
 
Philip Cardiff
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 835
Rep Power: 28
bigphil will become famous soon enoughbigphil will become famous soon enough
Hi evxta3,

As most(/all) of the solid models currently included in solids4foam use a Lagrangian approach (as opposed to Eulerian), the mesh motion is dependent on the displacement solution field. As a result, it is incorrect to use any mesh motion with the Lagrangian solid models.

If you did want to implement an Eulerian (or arbitrary Lagrangian Eulerian) solid model with arbitrary mesh motion, you would need to reformulation the governing equation to include a convection term as well as advecting all fields needed to calculate the stress (e.g. the displacement gradient or deformation gradient).

Kind regards,
Philip
bigphil is offline   Reply With Quote

Old   June 10, 2020, 07:09
Default
  #6
New Member
 
Tommaso
Join Date: Jan 2020
Posts: 4
Rep Power: 2
evxta3 is on a distinguished road
Thanks Philip.
evxta3 is offline   Reply With Quote

Reply

Tags
damping, fsi, solids4foam

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[solids4Foam] How to calculate drag coeff when using solids4Foam amuzeshi OpenFOAM CC Toolkits for Fluid-Structure Interaction 15 November 7, 2019 12:50
ANSYS Fluent rotation of SOLID drum filled with water coms0 FLUENT 0 October 26, 2019 09:49
Problem simulating the temperature rise in a composite material (chtMultiRegionFoam) Adam_K OpenFOAM Running, Solving & CFD 2 March 27, 2019 06:51
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 05:36
physical boundary error!! kris Siemens 2 August 3, 2005 00:32


All times are GMT -4. The time now is 18:10.