CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Special Topics > Mesh Generation & Pre-Processing

Structured Mesh of a Dragonfly wing while conducting Mesh Independence

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 18, 2021, 13:25
Smile Structured Mesh of a Dragonfly wing while conducting Mesh Independence
  #1
New Member
 
Rohan Sunil
Join Date: Jul 2021
Posts: 4
Rep Power: 2
rsunil is on a distinguished road
Hello everyone,



For my CFD project, I have been working on an Unsteady analysis over a 2D simplified dragonfly wing (corrugated wing) using DNS in StarCCM+ (laminar model).



Initially, I worked on a structured mesh for this profile and performed a mesh independence test at a Reynolds No. of 6000 and an angle of attack (AoA) of 9 degrees.


In this process, I obtained results where the flow behaviour changed from periodic to chaotic for a refined mesh. To be precise, I used a mesh of 450,000 cells for my study at various Reynolds numbers and AoAs and the results obtained were well within 3% deviation in comparison to a research article's results. I increased the cell count by a factor of 2, obtaining a mesh cell count of 1.75 million (for testing mesh independence). I tested the mesh at the same Re= 6000 and AoA= 9deg, the Coefficient of lift (Cl) plot was shown to be chaotic for the refined mesh (1.75 million cells) but periodic for the mesh of 450,000 cells. Meshes close to a cell count of 900,000 showed a periodic nature as well.


The flow was determined to be chaotic or periodic by taking the Fast Fourier Transform (FFT) of the Cl plots.


I was not able to pin-point where the problem could be as the quality of the Mesh seemed to be good as the cell qualities were >0.6 in ICEM CFD. So, I made a hybrid grid and tested for Mesh Independence at the same Re and AoA mentioned above. But for this mesh, there was no change from Periodic to Chaotic. It was periodic throughout.


The research article had obtained a Periodic result for the same conditions.



So, it would be really helpful to know what could be causing such changes for the structured grid and in such scenarios, how do I rely on which grid to choose ?


Thank you in advance for the help.


PS: Please let me know if further information is required
Attached Images
File Type: jpg structured.jpg (58.8 KB, 4 views)
File Type: jpg hybrid_Mesh.jpg (102.0 KB, 4 views)
rsunil is offline   Reply With Quote

Reply

Tags
dragonfly, hybrid grid, incompressible flow, structured grid, unsteady

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
[ANSYS Meshing] Structured Mesh inside an egg-like geometry BrunoCFD ANSYS Meshing & Geometry 1 October 31, 2018 15:48
[ICEM] Problem making structured mesh on a surface froztbear ANSYS Meshing & Geometry 4 November 10, 2011 09:52
[ICEM] Structured Mesh 3D Wing Tip Michiel ANSYS Meshing & Geometry 5 October 21, 2010 09:39
Structured Grid Definition craig shores Main CFD Forum 3 March 21, 2001 15:48
unstructured vs. structured grids Frank Muldoon Main CFD Forum 1 January 5, 1999 11:09


All times are GMT -4. The time now is 01:29.