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adaptive time step UDF

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Old   May 15, 2014, 11:21
Default adaptive time step UDF
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Tiziano Ghisu
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Hello everyone,

I wastrying to write a UDF defining an adaptive time step function for a time-dependent simulation ... but i encountered problems even before i arrived to the adaptive part, just by using the DEFINE_DELTAT UDF

while i was doing this, I encountered a very strange problem. While the simulation is stable for a given time step without the UDF, as soon as i use the udf to set the time step, the simulation blows up, even if i use the same time-step i was using earlier. The UDF I am using is very simple

/************************************************** *******************
UDF that changes the time step value for a time-dependent solution
************************************************** ********************/
#include "udf.h"

real dt=1.0e-4;
return dt;

How is this possible? Any suggestions? Thanks

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Old   November 25, 2014, 17:58
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Mahdi Torabi Asr
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Too late reply ;) but maybe works for others...

The problem is a result of using "Extrapolate Variables" option in calculation menu during adaptive time-step calculation (at least in my case).
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define_deltat, udf

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