CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > ANSYS Meshing & Geometry

ICEM Edge Params Bunching laws

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

Like Tree1Likes
  • 1 Post By zampa

LinkBack Thread Tools Display Modes
Old   September 17, 2009, 08:20
Default ICEM Edge Params Bunching laws
New Member
Tyler Sloss
Join Date: Sep 2009
Posts: 1
Rep Power: 0
twsloss is on a distinguished road
I am trying to make an automated front end for some blocking based grids I am making in icem, because I have to do a lot of them, and want to make it so people not familiar with icem can make grids. I want to be able to update the number of nodes to use on certain edges based on their length, but have been unable to figure out how the bi-geometric bunching law works. Thank you for any incite or help.
twsloss is offline   Reply With Quote

Old   October 16, 2009, 09:33
Default Search the Help
Retired from CFD Online
PSYMN's Avatar
Simon Pereira
Join Date: Mar 2009
Location: Ann Arbor, MI
Posts: 2,665
Blog Entries: 1
Rep Power: 39
PSYMN has a spectacular aura aboutPSYMN has a spectacular aura about
Look in the help... You can type Bigeometric into the search...

Look under Bunching laws for the description... Many of the other laws give the equations, but not this one.

Bunching Laws

BiGeometric The default bunching law. The two initial heights and ratios define parabolas in a coordinate system where the number of node points is the X-axis and the cumulative distance along the edge is the Y-axis. The parabolas are truncated where their tangent lines are identical; the spacing is linear between these points. If there are not enough nodal points to form this linear segment, a hyperbolic law is used and the ratios are ignored.
PSYMN is offline   Reply With Quote

Old   August 21, 2011, 15:31
New Member
Join Date: Aug 2011
Posts: 1
Rep Power: 0
Bastisendling is on a distinguished road
I'm having the same trouble. For a parametrisation i also need information on the Bigeometric bunching law. But i find the help info somewhat incomplete.
How exactly do the spacings and ratios define the parabolas?
My first guess would be:
The forumula for a parabola is f(x)=a*x^b
with a=Spacing and b=ratio.
Is this correct?
I really need the correct definition.
Thank you for help!
Bastisendling is offline   Reply With Quote

Old   September 13, 2011, 15:45
New Member
zampa's Avatar
Join Date: Aug 2011
Posts: 8
Rep Power: 9
zampa is on a distinguished road
Yesterday, I had the same problem.

Its not so difficult.
BiGeometric distribution use for the initial and end bunching law two parabol-functions: y(x)=a+bx+cx.

Using initial and end height and ratios, you can define this two parabolas.

The second target is to know where both parabols have the same tangent. You can express this using two ecuactions, and getting the start and end point where to distribute the cells uniformly.

Check the definition and think about it.
PSYMN likes this.
zampa is offline   Reply With Quote

Old   July 14, 2014, 08:43
Join Date: Nov 2011
Location: Germany
Posts: 40
Rep Power: 8
TrII4d is on a distinguished road
i know this topic was discussed long time before, but i do not understand what you mean exactly.

if i have the parabol function: y(x)=a+bx+cx

what are the variables a,b,c ? if i have two functions i become 6 unknown variables ... however 4 variables are discussed (spacing 1 and 2; ratio 1 and 2)

i'm really confused at the moment ... kindly help
TrII4d is offline   Reply With Quote



Thread Tools
Display Modes

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 On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Where's the singularity/mesh flaw? audrich FLUENT 3 August 4, 2009 01:07
fluent add additional zones for the mesh file SSL FLUENT 2 January 26, 2008 12:55
ICEM - mesh near wing trailing edge Joao Lourenco CFX 5 August 30, 2007 17:20
ICEM Extrude faces - Edge params. Santiago Orrego. CFX 0 June 19, 2007 12:08
Star mesh import problem chris1980 OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 20 May 8, 2006 01:07

All times are GMT -4. The time now is 02:44.