CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

aircraft simulation

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

LinkBack Thread Tools Display Modes
Old   December 18, 2011, 13:37
Default aircraft simulation
New Member
Join Date: Dec 2011
Posts: 2
Rep Power: 0
Vitali is on a distinguished road
I'm running simulation for external aerodynamics for a model aircraft (scale 1:33) previously tested in a wind tunnel. I'm using CFDesign with k-epsilon turb model. Conditions are the same as the wind tunnel conditions (scale, air speed,pressure) but results (lift and drag forces) are not according to the experiment...
what turbulance/laminar ratio and turbulance intensity have I to use?
thank you and sorry for my bad English
Vitali is offline   Reply With Quote

Old   December 18, 2011, 13:42
Senior Member
truffaldino's Avatar
Join Date: Jan 2011
Posts: 248
Blog Entries: 5
Rep Power: 10
truffaldino is on a distinguished road
k-e model is not good for this purpoce: Usually it gives garbage results when simulating aircraft, especially at low Reynolds numbers, when there are separations, transitions etc. For a model aircraft I would rather used non-PDE based software, such as XFLR5: It will give you much more better results.

truffaldino is offline   Reply With Quote

Old   December 18, 2011, 15:40
Join Date: May 2011
Location: London, UK
Posts: 45
Rep Power: 8
k_k is on a distinguished road
what is the Reynolds Number of your flow? if the Re of your flow is greater than 10^6 you are free to use any turbulence model without low Re corrections assuming the flow is fully turbulent. For flows or Re of the order 10^5, you have to use turbulence schemes with low Re corrections and have a very fine grid, y+ of 1 should be adequate. Even though there exists no universal low Re, transitional turbulence model, turbulence models with low Re corrections turned on should give acceptable results.

The turbulence intensity of the wind tunnel in which it was tested should be documented in the report on the wind tunnel experiment, so read that document carefully. It should be between 3% to 5% in many cases.

You can use a turbulence viscosity of the ratio between 5 to 10, to start with. The sensitivity of the solution on this value has to be tested along with grid independence check to prove confidence on the simulation results.
k_k is offline   Reply With Quote


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
Aircraft propeller simulation white FLUENT 3 January 4, 2016 03:14
GUI crash and simulation engine still running RPJones FLOW-3D 2 November 9, 2010 09:18
velocity profile export from a simulation onto another sudhirlv STAR-CCM+ 1 September 12, 2010 18:57
full simulation of an aircraft with propeller effect kdrbrk FLUENT 2 June 18, 2010 01:29
Aircraft Mesh Recommendation Sami FLUENT 2 April 2, 2006 13:23

All times are GMT -4. The time now is 03:07.