CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Panel methods for use in aeroelastic model

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 24, 2009, 12:49
Default Panel methods for use in aeroelastic model
  #1
New Member
 
Sara
Join Date: Sep 2009
Posts: 3
Rep Power: 7
Aero1 is on a distinguished road
I'm currently researching an aeroelastic model to help tailor composite lay-ups.
As part of this we need an aerodynamic model to provide the loads on an aerofoil for given geometry, then calculate the deflection, then iterate with the new geometry.
Due to the number of iterations and as these will be initial sizing calculations I think a panel method will be best, rather than a full 3D mesh.
I was wondering if anyone could advise on the major differences between the vortex lattice method and the panel method. Obviously they both have the limitations due to inviscid modelling, but what are the major differences in assumptions?
Am I right in thinking that VLM cannot account for thickness effects, but trhe panel method can? Are ther any advantages VLM has over the panel method?
The two programs I'm looking at in more detail are PANAIR and Tornado, does anyone have any advice on relative advantages/disadvantages
Any comments would be gratefully received
Many thanks
Sara
Aero1 is offline   Reply With Quote

Old   September 24, 2009, 18:02
Wink
  #2
Senior Member
 
sbaffini's Avatar
 
Paolo Lampitella
Join Date: Mar 2009
Location: Italy
Posts: 534
Blog Entries: 14
Rep Power: 17
sbaffini will become famous soon enough
Hi Sara,

On the theoretical side both the methods are developed from the same assumptions and, in some cases, they are completely equivalent (VLM are just a kind of panel method). Moreover, it is not strictly true that VL methods cannot handle thickness (they just need some attention to avoid uncorrect behaviors or unsolvability of the equations).

However, on the practical side, you're right...the panel methods (as meant by you) can handle thickness and, in general, allow for more flexibility while the VLM can only handle open surfaces on which some circulation exists (that is no actual code exists in which a VLM is modified to handle thickness). The difference between the two methods relies in the singularity distribution and boundary condition used to solve the same integral equation for the velocity potential (this is much more a math aspect...see Katz & Plotkin - "Low Speed Aerodynamics" for a very good reference to start with).

In my knowledge, there is no advantage in the use of a VLM as in the programming, which is far more easy with respect to a 3D panel code. Also, if you have to enter the code and modify it then a VLM should be much more easy to handle.

Being more specific, i.e., with respect to PANAIR and TORNADO, the first one comes from a joint effort of NASA and BOEING and is a really complex, flexible code developed in FORTRAN 77 (several papers should be available at http://ntrs.nasa.gov/search.jsp) but there is (almost) no way to modify it without a very big effort.

In contrast, Tornado is a less flexible VL code developed in MATLAB during a M.Sc. thesis work, not really different from what someone else, like you and me, could have done in his aero courses (except that Tornado works and has a lot of functionality continuously added). It goes without saying that you could learn to use it in less than a day and start coupling it with your structural solver in less than two weeks.

Maybe Tornado is the best choice, at least to start with. But if you want more functionality (like unsteadiness, boundary layer coupling, compressibility) and you're not scared by the effort than definitely go on PANAIR.

Tornado is freely available while PANAIR should be not (i don't know exactly).
sbaffini is offline   Reply With Quote

Old   September 25, 2009, 04:24
Default
  #3
New Member
 
Sara
Join Date: Sep 2009
Posts: 3
Rep Power: 7
Aero1 is on a distinguished road
Thank you, that's a really useful reply

Definitely given me some good points to think about, I just need to decide which is more suitable for this application!
Aero1 is offline   Reply With Quote

Old   September 25, 2009, 05:04
Default
  #4
New Member
 
Sara
Join Date: Sep 2009
Posts: 3
Rep Power: 7
Aero1 is on a distinguished road
Just to clarify... even though I won't be able to change the code in PANAIR, as it's a FORTRAN program I should be able to automate the input/output process, right?
Aero1 is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Kinetic air props model - conductivity HALF? Chris Bailey FLUENT 1 March 7, 2006 11:38
I just wonder why "SIMPLE" Junseok Kim Main CFD Forum 21 May 20, 2001 08:47
Katz & Plotkin - Panel Methods will kellar Main CFD Forum 3 December 13, 1999 11:11
3D panel methods Javier Main CFD Forum 3 October 20, 1999 23:25
Inverse Panel Methods Nibo Main CFD Forum 3 July 23, 1999 10:46


All times are GMT -4. The time now is 11:50.