CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

aspect ratio vs. y+

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 5, 2007, 09:31
Default aspect ratio vs. y+
  #1
hammam
Guest
 
Posts: n/a
Hi all

iam simulating 2d airfoil using c-grid topology , i want to trade off between y+ and aspect ratio , i use sst & ( Gamma-Theta) trnsition model which needs y+<1 , i meshed my domain by hex mesh using pre-mesh>edge meshing parameter tool.

i decrease the y+ by decreasing the edge spacing from the airfoil and i increase the number of nodes by using low edge ratio at the airfoil surface.

when i used a hyperbolic mesh with spacing 1e-4 it gives me a maximum aspect ratio of about 17000 .

and the convergence was unstable.

so what is the solution for that problem?

& what is the acceptable value for aspect ratio to use?

thanks Hammam
  Reply With Quote

Old   August 6, 2007, 10:19
Default Re: aspect ratio vs. y+
  #2
johnny
Guest
 
Posts: n/a
did you try running in double precision?
  Reply With Quote

Old   August 6, 2007, 11:27
Default Re: aspect ratio vs. y+
  #3
hammam
Guest
 
Posts: n/a
hello

excuse me would you please explain what is double precision, and how to use it?

regards
  Reply With Quote

Old   August 6, 2007, 11:41
Default Re: aspect ratio vs. y+
  #4
Gui
Guest
 
Posts: n/a
double precision is a more precise calculation (the values are represented with more digits).

you can get it before starting you run in the solver, where you can specify initial value file, you can click on "show advanced control" and there you can specify double precision
  Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
pressure eq. "converges" after few time steps maddalena OpenFOAM Running, Solving & CFD 69 July 21, 2011 08:42
[ICEM] Mesh along axis for a wedge gives elements with extreme aspect ratio sangrampp ANSYS Meshing & Geometry 0 November 17, 2010 07:57
High Aspect Ratio elements Flavio CFX 2 November 24, 2006 13:01
does aspect ratio affect analysis mahesh Main CFD Forum 2 October 10, 2005 10:12
Aspect Ratio at high turbulent and swirled flows zago FLUENT 0 May 19, 2004 03:37


All times are GMT -4. The time now is 08:32.