|
[Sponsors] |
June 1, 2009, 22:31 |
Relative Tolerance
|
#1 |
New Member
Rachel Harch
Join Date: Mar 2009
Location: RAdelaide
Posts: 2
Rep Power: 0 |
Hi
I was wondering if someone could help me to understand the details of relTol. I am unsure which has the stricter convergence criteria relTol=0.1 or relTol=0.001. I understand that if you set relTol=0 that you force the solution to converge to the solver tolerance, but I am not sure about other values. Cheers Rach |
|
June 4, 2009, 10:56 |
|
#2 |
Senior Member
Rishi .
Join Date: Mar 2009
Posts: 149
Rep Power: 17 |
Hello,
relTol is a parameter to say how much the intial residual should reduce in a particular time step. e.g. relTol=0, then default tolerence is targetted. (e-6 here) DICPCG: Solving for p, Initial residual = 1, Final residual = 7.55402e-07, No Iterations 35 ... DICPCG: Solving for p, Initial residual = 0.379232, Final residual = 3.38648e-07, No Iterations 34 e.g. relTol=0.01, then solver only tries to reduce residual by certain factor. This relTol is the order of magnitude reduction. So here Solver tries to reach a value below 1/100 of initial value. DICPCG: Solving for p, Initial residual = 1, Final residual = 0.00837542, No Iterations 24 ... DICPCG: Solving for p, Initial residual = 0.378888, Final residual = 0.00355735, No Iterations 23 So relTol=0.001 is stricter criteria & requires more iterations. Observe the number of iterations required in the above examples, for the same calculation. |
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
relative humidity and temperature by outlet | Bing | FLUENT | 5 | March 7, 2014 06:03 |
Relative humidity | amar | FLUENT | 0 | April 14, 2009 20:59 |
Tolerance in GAMBIT Help!!!!!! | Lottar | FLUENT | 0 | October 6, 2008 14:03 |
Relative Error in Grid Convergence | Christopher Haugh | Main CFD Forum | 2 | March 9, 2007 12:42 |
RELATIVE STREAMLINES !! | ozgur | FLUENT | 0 | March 25, 2004 20:34 |