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-   -   how to decrease time step based on previous result in openfoam (https://www.cfd-online.com/Forums/openfoam-programming-development/123976-how-decrease-time-step-based-previous-result-openfoam.html)

cctv September 25, 2013 05:35
how to decrease time step based on previous result in openfoam
 
Hi
how to decrease time step based on previous result in openfoam? for example, at first, I set deltaT=0.1, and runed to 10, then I want to change deltaT to 0.01, and begin from time 10, what should I do? I changed the deltaT to 0.01 in system/controlDIC, but find it just ran 10 times 10.01,not from 10.01 to 10.10. Is that correct? What should I do?
Thank.

cctv September 25, 2013 06:31
It seems because of time precision. I am wondering if there are any files except the uniform/time in the output folder would record time precision? I successfully change the deltaT in the same folder, but failed to do so by cp previous result from another folder. I am not sure the reason.

jherb September 26, 2013 04:21
Please post your system/controlDict. The relevant parameters are startFrom, startTime, stopAt, endTime, deltaT, writeControl and writeInterval. Perhaps also adjustTimeStep.

cctv September 26, 2013 06:34
Quote:
Originally Posted by jherb (Post 453658)
Please post your system/controlDict. The relevant parameters are startFrom, startTime, stopAt, endTime, deltaT, writeControl and writeInterval. Perhaps also adjustTimeStep.
startFrom latestTime;
startTime 0.0;
stopAt endTime;
endTime 2000.0;
deltaT 0.00001;
writeControl runTime;
writeInterval 10;
cycleWrite 1;
writeFormat ascii;
writeCompression uncompressed;
timeFormat general;
timePrecision 8;

jherb September 26, 2013 17:17
I do not know what cycleWrite means. Otherwise you might want to start from the tutorials, e.g. simpleFoam/motorBike:
Code:
startFrom      latestTime;
startTime 0.0;
stopAt          endTime;
endTime 10.1;
deltaT 0.01;
writeControl    timeStep;
writeInterval  1;

cctv September 27, 2013 16:56
Quote:
Originally Posted by jherb (Post 453792)
I do not know what cycleWrite means. Otherwise you might want to start from the tutorials, e.g. simpleFoam/motorBike:
Code:
startFrom      latestTime;
startTime 0.0;
stopAt          endTime;
endTime 10.1;
deltaT 0.01;
writeControl    timeStep;
writeInterval  1;
Have you tried before?


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