CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

How to set deltaT in controlDict?

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 12, 2019, 10:31
Default How to set deltaT in controlDict?
  #1
Senior Member
 
Raza Javed
Join Date: Apr 2019
Location: Germany
Posts: 183
Rep Power: 7
Raza Javed is on a distinguished road
Hello Everyone,


I have a question related to deltaT in controlDict.



What things do I need to consider while choosing the deltaT? I am running my simulation, there is a fluid flow in my case, and velocity of fluid is in range of 1e-3 m/s to 1.5 m/s. but my residuals for velocity are not getting down.



I exactly don't know but could it be also because of my deltaT because solver seems to be working, but the velocity residuals are very high (between 0.003 to 0.01).


Do I need to set deltaT by keeping in mind my velocity of fluid?


I shall be very thankful if someone can help me out in this.


Thank you
Raza Javed is offline   Reply With Quote

Old   October 9, 2023, 19:30
Default
  #2
New Member
 
Johannes
Join Date: Feb 2023
Posts: 3
Rep Power: 3
roo1valk is on a distinguished road
Have a look at the Courant Number and the Courant–Friedrichs–Lewy condition.
roo1valk is offline   Reply With Quote

Old   October 10, 2023, 14:08
Default
  #3
Senior Member
 
Saeed Jamshidi
Join Date: Aug 2019
Posts: 214
Rep Power: 7
saeed jamshidi is on a distinguished road
On the basis of my information, there are two ways for setting delta t:
First and easiest way is working with courant number directly; in controlDict set adjustableTimeStep to true.

Second way is to manually calculate time step. You should take the smallest cell volume (3D) and adapt your time step on the basis of it. See attached file.
However, in my opinion, it's better to use forst way, because the second way automatically is done by openfoam.
Good luck.
Attached Images
File Type: jpg 1696961216685.jpg (62.4 KB, 8 views)
File Type: jpg 1696961216697.jpg (44.5 KB, 5 views)
saeed jamshidi is offline   Reply With Quote

Reply

Tags
controldict, openfoam

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
feature or bug - deltaT issue lakeat OpenFOAM Running, Solving & CFD 29 August 8, 2020 01:34
Possible bug with stitchMesh and cyclics in OpenFoam Jack001 OpenFOAM Pre-Processing 0 May 21, 2016 08:00
Ansys SIG$ILL error loth ANSYS 3 December 24, 2015 05:31
Unexpected deltaT decrease in pimpleFoam simulation robyTKD OpenFOAM Running, Solving & CFD 9 June 27, 2014 06:52
[General] 2 datas on one plot Akuji ParaView 46 December 1, 2013 14:06


All times are GMT -4. The time now is 14:39.