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

fvm for unsteady term

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 5, 2020, 01:10
Default fvm for unsteady term
  #1
New Member
 
Jagan Mohan
Join Date: Dec 2019
Location: New York
Posts: 19
Rep Power: 4
jagan1mohan is on a distinguished road
Hello Friends, Greetings. I hope, you all are doing well. I'm trying to build an application in OpenFOAM. I'm starting from scratch as I think this is best way to learn what exactly happens behind screen. With all others details implemented into main function, compilation successful, lets focus on following.



for (int i = 0; i <= 10; i++)

{
solve
(
fvm::laplacian(kTh, T)
);
runTime++;
runTime.write( );
}


As you can see, I'm solving steady Laplace conduction equation with no source terms. ControlDict settings are timeStep is 1 (these are now steady iterations) with some startTime and endTime.



1. What I observe is in first step itself, final residual goes to e-6 and it says iterations 46. What are these iterations and where are they coming from?



2. In all subsequent steps, residual does not change at all and so called iterations are zero.


3. When we write Laplacian solver in Matlab using FV Method, we see a residual plot which decreases. Why are we not seeing such thing in OpenFOAM?


4. Also, when solver knows that residual is less than tolerance value, why does not it stop iterating? (Like we see in Matlab code).


Thank you,
Jagan Mohan.
jagan1mohan is offline   Reply With Quote

Reply

Tags
fvm::ddt(), fvm::laplacian

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
How to add Source term (2) for PYROLYSIS - reactingOneDim Kummi OpenFOAM 10 April 12, 2021 21:11
FVM Source term discretisation vkoppejan Main CFD Forum 7 November 29, 2015 09:26
Source term in OpenFOAM: fvc vs fvm Sylv OpenFOAM Programming & Development 0 November 20, 2014 06:39
ATTENTION! Reliability problems in CFX 5.7 Joseph CFX 14 April 20, 2010 15:45
FVM discretization of diffusion term on crvlnr gr Michail Main CFD Forum 3 March 14, 2008 06:52


All times are GMT -4. The time now is 18:09.