CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Slow Transient Solution

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 19, 2014, 19:41
Unhappy Slow Transient Solution
  #1
New Member
 
Join Date: Nov 2013
Posts: 5
Rep Power: 12
scoobysimon is on a distinguished road
Hello,

I am doing a 2D transient simulation of an aerofoil passing a cylinder to simulate a wind turbine blade passing a tower using a sliding mesh. At the moment my solution is taking quite a while (over 24 hours).

A problem I am finding is that I have set the maximum iterations per time-step to be 800 and it seems to use up all 800 for nearly every time-step. I was under the impression that after the solution settles down it should only take ~50 iterations. I have set the time step to be the time taken for the mesh to slide the length of the smallest element.

For example I am plotting Cl vs time throughout the solution and I understand that the solution needs to settle (possibly due to limiting it to 800 iterations/time step) but I would assume that after a while.

Any help or advice would be appreciated, I have attached some images of the mesh if that helps.
Attached Images
File Type: jpg mesh1.jpg (84.8 KB, 15 views)
File Type: jpg mesh2.jpg (97.4 KB, 14 views)
File Type: jpg mesh3.jpg (90.8 KB, 11 views)
scoobysimon is offline   Reply With Quote

Old   March 21, 2014, 04:19
Default
  #2
Senior Member
 
Bionico's Avatar
 
Flavio
Join Date: Sep 2011
Location: Brescia, Italy
Posts: 181
Rep Power: 15
Bionico is on a distinguished road
Hello scoobysimon,
I'm not expert in airfoil (I've never simulated one), but I'd say that usually in transient simulation the number-it/time-step is less important than the time-step value: I never used such a large number of it/time-step (max 20-30).
I suggest trying 20 it/time-step and reducing the time-step checking your time-discretization.

Regards
__________________
Bionico
Bionico is offline   Reply With Quote

Reply

Tags
slow, solution, transient analysis

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
Seeing results at different time steps of a transient solution. juZby FLUENT 4 January 21, 2013 00:17
Transient Solution looks like Steady State ljwnow FLUENT 0 March 26, 2012 02:54
transient solution faw FLUENT 2 March 12, 2012 12:25
Best practice for transient simulations? siw CFX 5 October 30, 2010 06:45
Problem with transient solution of flow past a row of cylinders jostanek Main CFD Forum 0 January 6, 2010 13:16


All times are GMT -4. The time now is 03:11.