CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

fluctuation in force coefficients with dynamicTopoFvMesh

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 1, 2018, 02:55
Default fluctuation in force coefficients with dynamicTopoFvMesh
  #1
New Member
 
Join Date: Oct 2016
Posts: 9
Rep Power: 9
sepehr_s is on a distinguished road
Hello
i want to simulate pitching and plunging airfoil with large amplitude in ground effect. because of large amplitude i use remeshing with dynamicTopoFvMesh.
first i simulate pitching and plunging airfoil out of ground effect. airfoil movement and remeshing is very good but when i active flow solver (pimpleDyMFoam), forces coeff (cl , cd) have fluctuations.

i solve this problem with dynamicFvMesh and compare result with kinsey and dumas, the results had very good agreement. then i simulate that problem with remeshing dynamicTopoFvMesh that results have fluctuation.
in both solver initial and boundary conditions are the same and flow solver is pimpleDyMFoam or icoDyMFoam with foam extend 3.1.
i examine different scheme, time step , ... but no effect on fluctuation.

what is the reason of this fluctuations?
how can i remove this fluctuation?
how can you help me please?
thanks.


sepehr_s is offline   Reply With Quote

Old   May 1, 2018, 17:10
Default
  #2
Retired Super Moderator
 
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,975
Blog Entries: 45
Rep Power: 128
wyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to all
Quick answers/questions:
  1. If you are running in parallel, try running a few iterations in serial mode instead. This is just so that you can put aside any influences that parallel decomposition may have on the flow field.
  2. If you are using PIMPLE, then try setting the "nOuterCorrectors" parameter in "fvSolution.PIMPLE" to a value larger than 2 or 3 - see this page for more details: https://openfoamwiki.net/index.php/O...hm_in_OpenFOAM - hopefully this will help stabilize the flow field after each mesh motion.
  3. Have you tried using Radial Basis Function (RBF) mesh deformation, instead of dynamicTopoFvMesh?
__________________
wyldckat is offline   Reply With Quote

Old   May 2, 2018, 03:41
Default
  #3
New Member
 
Join Date: Oct 2016
Posts: 9
Rep Power: 9
sepehr_s is on a distinguished road
i ran the simulation in serial mode.
i set nOuterCorrectors up to 100 but after each remeshing of domain and remapping, the result show jumpping.
i didn't try RBF, because i must consider the ground effect and airfoils in tandem configurations.
thanks for rapid answer Bruno.
sepehr_s is offline   Reply With Quote

Reply

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
ActuatorDiskExplicitForce in OF2.1. Help be_inspired OpenFOAM Programming & Development 10 September 14, 2018 11:12
Sectional force coefficients tfuwa OpenFOAM Post-Processing 1 June 27, 2013 06:49
[OpenFOAM] spatial distribution of force coefficients in paraview&openfoam kkpal ParaView 1 April 21, 2013 07:15
Force can not converge colopolo CFX 13 October 4, 2011 22:03
Density for calculating Force Coefficients ste_lakey CFX 2 September 19, 2005 04:35


All times are GMT -4. The time now is 23:53.