# Non-Reflecting BC

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 LinkBack Thread Tools Display Modes
 December 26, 2006, 06:54 Non-Reflecting BC #1 Bounecer Guest   Posts: n/a I've written my own code program simulating 2D, incompressible and viscous flow about an airfoil. I'm using for that structured C-grid generation (far-field boundary is 15xcord). The problem is that my code program diverges after about 5000 itterations. Mister Ganesh who is an active and helpfull on this Site suggested to use non-reflecting BC at far-field instead of free stream BC. My question is: Are that type of BC can be applied to incompressible flow, and how can i implement non reflecting BC.

 December 26, 2006, 17:52 Re: Non-Reflecting BC #2 Harish Guest   Posts: n/a Most of the non reflecting BC are derived from the characteristics of the Euler equation and they usually try to absorb correctly the outgoing acoustic,vorticity and entropy wave and are derived for systems where the speed of sound is finite. You can try implementing an absorbing buffer zone.A simple way of implementing it is as follows: The equation would be df/dt=RHS+sigma* f where the factor sigma=sigma0*((x-xb)/D)^beta.sigma0 is a constant based on the grid ( I use sigma0=2/dx for most cases, beta=3 ).D is the thickness of the sponge layer.xb is the location where the sponge layer begins.A sponge layer of 10-20 points works for me. --------------------------------------|------------| xb<---D----->xn I have not tested the buffer zone for incompressible systems and am not sure if they might help. =)

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Vinayak Barve FLUENT 1 June 2, 2016 09:42 bhanwar Fluent UDF and Scheme Programming 5 September 13, 2012 02:05 Rachel FLUENT 1 July 1, 2008 18:20 kupiainen OpenFOAM Running, Solving & CFD 15 July 13, 2005 08:00 Tengc FLUENT 1 November 17, 2004 14:58

All times are GMT -4. The time now is 13:47.

 Contact Us - CFD Online - Top