
[Sponsors] 
August 16, 2005, 15:09 
3D meshing in Ga,bit

#1 
Guest
Posts: n/a

My question is related to meshing in GAMBIT. It is a 3d geometry circular pipe geometry with 2 inlets one at the bottom (water) and other at 1m from base (for air). Geometry is made from Pipepipe intersection by thin rectangular brick.
outlet          airinlet (90 degree inlet)     waterinlet when i try to edge mesh (inlet circular domain) before putting boundary layer .............the inlet surface (consisting of 5 segments) meshes in nonuniform manner i.e. each segment makes different nodes. Is there any option or procedure in gambit through which i can uniformly distribute nodes over entire inlet circular surface (let say 60 nodes over all circular domain)i.e. while circular domain consists of 5 segemnts. 

August 16, 2005, 15:42 
Re: 3D meshing in Ga,bit

#2 
Guest
Posts: n/a

You can specify how many nodes you want on any edge. There's a drop down box next to where you put the interval size and you can change that to interval count. You can select all the edges you want to have the same number of nodes and mesh them all at the same time by specifying the interval count. Is that what you were looking for? Or is the node spacing nonuniform along the edge segment (i.e. the first node spacing on the edge is .1m, but the next node spacing is .2m or something like that)?
Good luck, Jason 

August 16, 2005, 18:51 
Re: 3D meshing in Ga,bit

#3 
Guest
Posts: n/a

thanks for the reply.
Yes i did the same way as u have said but it did not work due to geometry made of three volumes two pipes at 90dgree joined by thin rectangular brick. This means if u look from top (or down)) one will see 3 segment on the circular surface(diameter of pipe). if i select interval count and select all the edges than the distribtuion of nodes are uniform for 2 opposite sides i.e. small edges gives same number of clustered nodes which large edges gives uniform. 

August 17, 2005, 09:43 
Re: 3D meshing in Ga,bit

#4 
Guest
Posts: n/a

Oh, so the edges have different lengths?
Not sure if there's an automatic way to do this then. If you can merge the edges then it'll space them evenly. Otherwise, you can get the arc length of each line segment (using the Summarize command in the GeometryEdge operations... it looks like an i). Then you can calculalate how many nodes should be on each segement to get approximately even increments. Nodes on i = Length of i / (sum of all L) * Total Number of Nodes on Loop You'll have to round the numbers to even integers, but this might help. Hope this helps, and good luck, Jason 

August 18, 2005, 15:55 
Problem importing a .cas file from gridgen

#5 
Guest
Posts: n/a

I am working on an electrostatic precipitator and started of with a simple 2D mesh. I was trying to load this in Fluent and it gives me an error: "invalid section id". can someone please tell me what the problem is.
thanks in advance 

August 18, 2005, 16:02 
Re: Problem importing a .cas file from gridgen

#6 
Guest
Posts: n/a

Derick,
Have you tried creating blocks for each domain? I know its a bit stupid the way Gridgen works but you can try that and let me know if it works. Many thanks, Miqdad 

August 19, 2005, 11:10 
Re: Problem importing a .cas file from gridgen

#7 
Guest
Posts: n/a

hey Miqdad,
i got the thing rectified...well it was some problem with the way i was exporting the .cas file. thanks for the help. but surely more to come!! derick 

August 19, 2005, 14:49 
Re: Problem importing a .cas file from gridgen

#8 
Guest
Posts: n/a

No problems at all,
Let me scare you a bit. After you read the mesh in Fluent, check your grid for negative volume to make sure its a proper grid. If you see any negative volume there then some thing is not right! Thanks, I know there is more to come. Good luck and keep posting. 

August 19, 2005, 15:38 
Re: Problem importing a .cas file from gridgen

#9 
Guest
Posts: n/a

yeah negative volume means inverted volumes. and wat is inverted volume i dont know :S i think it is something to do with singularity . am i right ?


Thread Tools  Search this Thread 
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
[ANSYS Meshing] Migrating from GAMBIT to ANSYS Meshing  DavidCFD  ANSYS Meshing & Geometry  1  April 1, 2011 06:22 
Best Meshing scheme for Cylinder  Nutrex  Main CFD Forum  4  July 29, 2008 12:03 
Meshing locks workbench window.  andy2o  CFX  0  February 1, 2008 06:01 
Singularity of grid?Volume meshing vs face meshing  Ken  Main CFD Forum  0  September 4, 2003 12:09 
Volume Meshing & Face Meshing? singularity of grid  ken  FLUENT  0  September 4, 2003 12:08 