# On grid independent solution for pulsatile flow

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

 June 7, 2005, 14:01 On grid independent solution for pulsatile flow #1 David Guest   Posts: n/a Hi all, I am modelling a 2d pulsatile flow in a conical tube for an undergraduate project. This tube is about 15 cm long with a radius varying between 6.5 mm and 12.5 mm. I use a velocity inlet and a pressure outlet. I am trying to acheive an grid independent solution. To do so, I compare a grid having 200 000 cells vs. one having 800 000 cells. I have set-up monitors for various quantities including the area-weighted velocity magnitude of points lying on the centerline (symmetry axis) of the tube. When comparing the 2 cases I get satisfying results. My problem is when monitoring the integral of wall shear stress on the wall of the tube. I get vary different values (30% error) when taking the cycle time-average. My question is does this mean that my grid is not fine enough? Can someone give an order of magnitude as to how many cells I should be using to obtain a grid-independent solution? From what I had read I tought 200 000 cells would be more than enough for a laminar case... Any comments would be much appreciated. Thanking you in advance for your time. David

 June 8, 2005, 09:54 Re: On grid independent solution for pulsatile flo #3 David Guest   Posts: n/a Hi Aaron, Thank you so much for your comments. They really give me a good explanation. One other question: At some point you mention :"Don't make any changes to the grids (other than grid size)[...]". Does that mean that grid adaption should be avoided. In my case I used it because some of the cells near the wall did not have a good aspect ratio near the wall (both for the 200k and 800k grids). Is this a potential source of more trouble that need to be? Best Regards, David

 June 8, 2005, 16:20 Re: On grid independent solution for pulsatile flo #5 David Guest   Posts: n/a Many thanks Aaron, Your comments are very much appreciated! Best Regards, David

 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 holg FLUENT 0 July 13, 2009 17:10 CFX Begineer CFX 0 October 27, 2002 11:54 Art Stretton Phoenics 5 April 2, 2002 05:59 Seb Main CFD Forum 13 May 22, 2001 13:37 Hesham M. Aly FLUENT 2 October 5, 2000 08:24

All times are GMT -4. The time now is 17:10.

 Contact Us - CFD Online - Top