Query regarding grid generation of multi scale geometry

zaidhasany · February 25, 2011, 02:01

i encounterd with a problem related to the grid generation in GRIDGEN, my geometry dimension scale vary with 10e4, hence it has beome quite difficult to model properly, basically i have to make grid in between two spherical geometries, radii are of the order of 5 cm and the clearance is 0.001 cm.
can any one guide me!!

rmatus · February 25, 2011, 10:38

Zaid:

That range of geometric scales should not be difficult for Gridgen to handle. What are the symptoms of your problem?

Rick

zaidhasany · March 1, 2011, 05:17

thanks a lot for your reply, when i created the connectors on the data base (igs format) due to LSQ issue or else, connectors overlap each other or come closer which would definitely make problem to make the domain and block.

rmatus · March 1, 2011, 10:15

Hi Zaid:

Connectors created on a database in Gridgen will be directly on the database curve or surface, so if the database entities are not crossing the grid should not cross.

Once thing that may cause the connectors to appear to cross when dealing with very small scales is the graphics resolution. Gridgen does all its internal calculations and storage in double precision, but the display graphics are only single precision by default. As a result, sometimes when you are zoomed in to a very small area the grid might not be displayed at its precise location.

You can change this default behavior in the Display Commands menu. Choose FramBuf, and then select double precision graphics.

Hope this helps,
Rick

February 25, 2011, 02:01	Query regarding grid generation of multi scale geometry	#1
zaidhasany New Member Zaid Join Date: Feb 2011 Posts: 2 Rep Power: 0	i encounterd with a problem related to the grid generation in GRIDGEN, my geometry dimension scale vary with 10e4, hence it has beome quite difficult to model properly, basically i have to make grid in between two spherical geometries, radii are of the order of 5 cm and the clearance is 0.001 cm. can any one guide me!!

February 25, 2011, 10:38	What kind of problems are you seeing?	#2
rmatus Senior Member Rick Matus Join Date: Mar 2009 Location: Fort Worth, Texas, USA Posts: 116 Rep Power: 17	Zaid: That range of geometric scales should not be difficult for Gridgen to handle. What are the symptoms of your problem? Rick

March 1, 2011, 10:15	Try Double Precision Graphics?	#4
rmatus Senior Member Rick Matus Join Date: Mar 2009 Location: Fort Worth, Texas, USA Posts: 116 Rep Power: 17	Hi Zaid: Connectors created on a database in Gridgen will be directly on the database curve or surface, so if the database entities are not crossing the grid should not cross. Once thing that may cause the connectors to appear to cross when dealing with very small scales is the graphics resolution. Gridgen does all its internal calculations and storage in double precision, but the display graphics are only single precision by default. As a result, sometimes when you are zoomed in to a very small area the grid might not be displayed at its precise location. You can change this default behavior in the Display Commands menu. Choose FramBuf, and then select double precision graphics. Hope this helps, Rick

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Grid Generation	Raghunandan K.V.	Main CFD Forum	2	October 4, 2008 10:26
elliptic grid generation	prapanj	Main CFD Forum	1	November 19, 2007 17:53
Grid generation package for turbomachinery	John	Main CFD Forum	6	March 21, 2001 10:37
Elliptic Grid Generation	R.V.Ramkumar	Main CFD Forum	2	July 5, 1999 12:06
How to do Grid Generation for the FLUENT?	timea	Main CFD Forum	2	April 7, 1999 10:03

March 1, 2011, 05:17		#3
zaidhasany New Member Zaid Join Date: Feb 2011 Posts: 2 Rep Power: 0	thanks a lot for your reply, when i created the connectors on the data base (igs format) due to LSQ issue or else, connectors overlap each other or come closer which would definitely make problem to make the domain and block.