# Laminar flow over airfoils

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

 June 16, 2007, 14:55 Laminar flow over airfoils #1 Murthy Guest   Posts: n/a Hi people!!! can anyone please tell me if non-convergence of solution can be taken as an indication of change in flow regime?? like from laminar to turbulent ; steady to unsteady etc..

 June 16, 2007, 14:59 Re: Laminar flow over airfoils *NM* #2 Murthy Guest   Posts: n/a

 June 16, 2007, 17:32 Re: Laminar flow over airfoils #3 Phil Guest   Posts: n/a Non-convergence can be caused by a huge number of things. Even experts need to monitor convergence and sometimes go back and improve the grid. However if you try to solve an unsteady problem with the steady solver you will experience this problem. You could try using the unsteady solver to see if the solution changes. I'm unsure about the turbulent transition although solving in laminar is simply computing all the individual turbulent scales directly ie not modeling them (DNS), but needs huge grids up to 8million cells to properly resolve the turbulent regions. I know this is incredibly difficult to converge. Using a turbulence model for laminar flow shouldn't hinder convergence but is a waste of time. Also when something downstream affects something upstream later in the solution, it causes the code's guesses to unconverge for a while as they re-calculate the new solution. YOU SHOULD LOOK UP WIKIPEDIA.COM, ANY CFD BOOK, OR THE FLUENT/CFX DOCUMENTATION. hope this helps Phil.

 June 19, 2007, 11:43 Re: Laminar flow over airfoils #4 Murthy Guest   Posts: n/a Thanks Phil... you said "Using a turbulence model for laminar flow shouldn't hinder convergence but is a waste of time." so do u suggest that turbulence models are capable of solving laminar problems? and do u think i should try with a refined grid, the same problem?

 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 shashwat Main CFD Forum 0 April 4, 2008 02:20 ranjith CFX 4 November 21, 2007 01:38 mech FLUENT 4 February 1, 2007 15:18 mech FLUENT 0 January 27, 2007 19:51 kim FLUENT 2 April 4, 2002 02:44

All times are GMT -4. The time now is 17:08.