# Two-peak tracer curve

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

 October 30, 2003, 16:02 Two-peak tracer curve #1 jim Guest   Posts: n/a Hi, all, I am trying to predict the results of a tracer test with CFX5.6(the tank I simulatd has 5 baffles, tracer was pulse injected in the inlet within 10 s). Then I found that there are two peaks in the tracer curve. Is this normal or not. If it's normal, how to explain it? If not, what's the possible reason of that? BTW: Generally, how to improve the accuracy of a tracer simulation by CFX? Regards! Jim

 October 30, 2003, 22:14 Re: Two-peak tracer curve #2 Jeff Guest   Posts: n/a Jim, See my previous post for Bacterial Dose. Same advice applies. Be sure to use the second order differencing in both time and space. One or the other won't do it. I think your double peak can be explained if some of the flow short circuits (heads straight for the outlet) and some of it gets hung up behind the baffles and released with a time delay from the first "slug" of material. Animate your isosurfaces of tracer material to see if this is really what is happening. Jeff

 October 30, 2003, 23:42 Re: Two-peak tracer curve #3 jim Guest   Posts: n/a Hi, Jeff Yes, I did see the tracer mass seperated into two parts in the animation result. But I never saw any literature reported double peak tracer curve(with similar geometry). So I will try to use the second order differencing in both time and space as you suggested. Could you please give more detailed information on how to set the second order differencing in both time and space in CFX5.6? Thanks a lot for your advice! Regards! Jim

 November 1, 2003, 15:44 Re: Two-peak tracer curve #4 Jeff Guest   Posts: n/a Spacial second order is the default (high resolution scheme) as available on the solver control panel in Pre. Second order in time requires a CCL command to set "Second Order Upwind Scheme" (I think this is what it's called). I can't recall exactly the syntax, but if you search the rules file, you'll find the proper syntax and where to put it in your CCL. Your support person should be able to help you find this as well. Jeff

 November 1, 2003, 18:49 Re: Two-peak tracer curve #5 Jim Guest   Posts: n/a Jeff, Thanks a lot, I will try that! Best regards! Jim

 November 2, 2003, 08:05 Re: Two-peak tracer curve #6 Robin Guest   Posts: n/a If you are using CFX-5.6, it is available in the GUI. -Robin

 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 Robert@cfd ANSYS Meshing & Geometry 20 November 11, 2011 05:59 tommymoose ANSYS Meshing & Geometry 0 August 5, 2011 16:02 KB Main CFD Forum 2 June 5, 2007 16:45 Graeme CFX 11 October 25, 2005 10:02 Chie Min CFX 5 July 12, 2001 23:19

All times are GMT -4. The time now is 00:57.

 Contact Us - CFD Online - Privacy Statement - Top