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

Hovering flight and Reynolds no.

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 25, 2008, 12:06
Default Hovering flight and Reynolds no.
  #1
Zonexo
Guest
 
Posts: n/a
Hi,

I've used my NS solver to solve flow past moving airfoils. The Reynolds no. (Re) is obtained by calculating flow past the airfoil. So now if I want to simulate a hovering flight, what changes must I make? How do I calculate the Re since velocity is now zero?

I have searched the net and there's a paper (An improved method for calculating flow past flapping and hovering airfoils) which uses Re = k*a*c /v where k=reduced frequency, a=horizontal oscillation amplitude of airfoil, c=chord, v=viscosity. Is there any other definition?

Also, in hovering, lift is balanced by the weight and thrust is zero. So in my calculation, if the lift is not equal to the weight or if there's thrust, does it mean that this Re definition or my results will be invalid, cos the inbalance will result in the body moving?

thank you!
  Reply With Quote

Old   March 28, 2008, 06:26
Default Re: Hovering flight and Reynolds no.
  #2
Anton Lyaskin
Guest
 
Posts: n/a
From dimensional considerations, there should be just frequency, not reduced frequency. Reduced frequency is dimensionless (it's inverted Stroukhal number), so k*a will give you meters instead of meters per second.
  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
changing Mesh with known new points for shape kilerskill OpenFOAM 15 February 16, 2011 04:21
CL vs AOA plot low reynolds difficulties andy_r FLUENT 3 March 25, 2009 10:14


All times are GMT -4. The time now is 09:40.