CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

structured grid and/or increase convergence rate

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

LinkBack Thread Tools Search this Thread Display Modes
Old   May 12, 2006, 03:36
Default structured grid and/or increase convergence rate
Ashish Pande
Posts: n/a
Dear all,

I am Ashish Pande, a new user of Fluent. I am trying to model 3-D, 1 phase, batch/continuous, incompressible, steady state model in a single rushton turbine stirred tank. Latter on, I want to extend this to 2-phase solid suspended model. It is taking too much time for convergence, just for 1-phase calculations. I am using Multiple reference frame model. I have roughly 1,50,000 nodes and 6,50,000 cells. To speed up the convergence, I've tried to play with under-relaxation parameters and changing from SIMPLE to PISO, but that is not not much use. Now my problems are as follows.

1) I have generated unstructured mesh in gambit. Should I switch over to structured mesh to speed things up?

2) I tried to generated structured mesh. In the inner zone (around impeller) I could use quad-map for faces everywhere except the caps of the cylinder enclosing the zone and the bottom of frustum. (To use quad-map, I had to split up the faces and so on). Now the modelling guide says that at least one of the surfaces must not be sub-mappable for cooper scheme to apply (so this condition is fulfilled in my case) and non-source faces must be mappable, which is true in my case. But even then, when I select the source faces as (split faces of) the bottom of frustrum and caps of zone, error says that either the face is not sub-mappable or the choice of source face is not correct. Does it mean that the source faces also have to be sub-mappable for Copper? It wud then violate one of the conditions given above.

3) Is there any other way to use structured/block-structured grid for my case? (I mean without going for cooper scheme)? Most of the literature on rushton turbine modelling uses structured grid (but only half of the geometry of the tank is modelled, for other half symmetry condition is used). Also I don't know how to create block-structured grid in gambit.
  Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
error and convergence rate HaKu Main CFD Forum 0 April 28, 2011 17:39
Structured to Unstructured grid Sen Main CFD Forum 2 March 2, 2011 11:33
Block Structured Grid aurel Fidelity CFD 0 October 21, 2005 09:17
Grid Convergence Tests CFDtoy FLUENT 0 April 29, 2004 17:23
Grid generator for structured grids Tore Myhrvold Main CFD Forum 5 January 21, 1999 08:09

All times are GMT -4. The time now is 23:37.