CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

How to reduce total number of elements?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 23, 2012, 04:32
Default How to reduce total number of elements?
  #1
New Member
 
Pouya
Join Date: Feb 2012
Posts: 17
Rep Power: 5
Pouya is on a distinguished road
Hi every one!

I've a couple of questions! I'm using ANSYS Mechanical APDL to create geometry and mesh. The geometry is simple (flow around a circular cylinder!). I've used "Flotran 142" as fluid element.

I want to reduce total number of elements specially in the z direction (assuming xy on the cross section). And of course I have to reduce Y+ in z direction to a value of below 1.

I decided to use finer elements around the riser (similar to the picture). I'm using structured mesh. In this picture, 2 elements are connected to one. I should merge nodes and keypoints. Is it possible? (I know it is! I've extracted the picture from an OMAE paper!)
But how? Is it possible in Mechanical APDL? Is any special command necessary? or maybe I've to use another meshing software?!!!

I was wondering if you'd mind explaining it! Thank you.
Attached Images
File Type: jpg Untitled.jpg (70.9 KB, 25 views)

Last edited by Pouya; October 29, 2012 at 14:40.
Pouya is offline   Reply With Quote

Old   October 23, 2012, 15:38
Default
  #2
Senior Member
 
Chris DeGroot
Join Date: Nov 2011
Location: Canada
Posts: 387
Rep Power: 6
cdegroot is on a distinguished road
A structured mesh has the elements ordered in rows and columns. The picture you are showing is a block structured mesh, meaning there are certain blocks in which the mesh is structured (with a row/column format). I'm not sure about creating the mesh in the software you mentioned; never tried it. I would be more concerned about whether or not the CFD solver you are going to use will accept meshes with faces that aren't connected one-to-one. What solver are you going to use?
cdegroot is offline   Reply With Quote

Old   October 23, 2012, 16:47
Default
  #3
New Member
 
Pouya
Join Date: Feb 2012
Posts: 17
Rep Power: 5
Pouya is on a distinguished road
Thanks for your answer. I'm using CFX & I must use LES or DES turbulence model. As you mentioned faces of elements aren't connected.
Pouya is offline   Reply With Quote

Old   October 23, 2012, 16:59
Default
  #4
Senior Member
 
Chris DeGroot
Join Date: Nov 2011
Location: Canada
Posts: 387
Rep Power: 6
cdegroot is on a distinguished road
Okay. So while I can't comment on how to construct the mesh, you shouldn't have a problem in CFX with faces that do not line up properly. CFX is very good at handling this using the General Grid Interface (GGI) connections. Just make each block a separate fluid domain and define a conservative domain interface between them. Good luck.
cdegroot is offline   Reply With Quote

Old   October 24, 2012, 16:54
Default
  #5
New Member
 
Pouya
Join Date: Feb 2012
Posts: 17
Rep Power: 5
Pouya is on a distinguished road
Thanks Chris. Today I studied about GGI! I think you are right. I'm going to try it!
Pouya is offline   Reply With Quote

Reply

Tags
ansys apdl, structured mesh

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
AMI speed performance danny123 OpenFOAM 19 October 24, 2012 07:44
mesh file for flow over a circular cylinder Ardalan Main CFD Forum 6 April 17, 2010 23:40
[ICEM] How to find number of elements, nodes for Tetras Karatix ANSYS Meshing & Geometry 6 March 31, 2010 09:40
RPM in Wind Turbine Pankaj CFX 9 November 23, 2009 05:05
Finite element method - number of elements poornima Main CFD Forum 6 April 14, 2006 07:23


All times are GMT -4. The time now is 22:53.