4.5.3.1.2 Transient Simulation Control:

The parameters startTime and endTime determine the start time and the end time for the transient simulation. Modifying the default value of startTime to values other than "0.s" can be used in conjunction with time dependent process temperature or coefficient models to achieve some additional flexibility.

By using the interface Parameter timeStepMode one can choose between three different time step control algorithms:

const constant time steps given by the value of the parameter prntstepTime. The last time step is truncated if necessary to reach the endTime exactly.

iterative the initial time step is prntstepTime. All further time steps result from the number of iterations (iterationCount) it took for the iterative solving algorithm to compute the results:

if ( iterationCount < (iterationLimit * lowIterationLevel) )
   stepTime = stepTime * timeStretch;
if ( iterationCount < (iterationLimit * highIterationLevel) )
   stepTime = stepTime * timeReject;

step-doubling the initial time step is prntstepTime. All further time steps are computed by following the two-level step doubling strategy [20,40].

All interface parameters of the PromisNTSetupModel instance dedicated to the control of the transient simulation flow are listed in Table 4.5.

Table 4.5: PROMIS-NT setup Model Parameters concerning the transient simulation time

Name	Type	Description
startTime	MdlString	The start time of the transient simulation. The time unit can be specified by appending s, min, hour, or day to the numerical value and defaults to s. Default: "0.0 s"
endTime	MdlString	The end time for transient simulation. Default: "0.0 s"
stepTime	MdlString	The length of the initial time step. Default: "1.0 s"
timeStepMode	MdlString	The transient time stepping mode. One of "const", "iterative", "step-doubling" modes. Default: "step-doubling"
highIterationLevel	double	Time steps are decreased when solving the equation system requires more than highIterationLevel * iterationLimit iterations. (Table 4.8) Default: 0.4
lowIterationLevel	double	Time steps are increased when solving the equation system requires more than highIterationLevel * iterationLimit iterations. (Table 4.8) Default: 0.2
transError	double	The error limit for the transient integration. If the occurring error is too large the time step will be rejected and if the limit fits the time step will be stretched Default: 1e-2
timeStretch	double	Stretching factor for time stepping Default: 2.0
timeReject	double	Rejection factor for time stepping Default: 0.5