Thermal_control_data
Contents
Data Structure: Thermal_control_data |
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"Thermal Control Data" data structure |
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Thermal_control_data NUM=ival where ival is the data structure number |
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Overview The Thermal_control_data structure defines solution algorithm, output and termination data for the current stage for the thermal field. It must be defined for both thermal only simulations and also for multi-field simulations where the thermal field is active
Notes •Many of the parameters are set by default. The minimum data comprises the termination data. •For single field analysis the no further data for the current stage is read subsequent to reading the Thermal_control_data structure. •One data structure is required for each analysis stage.
Examples demonstrating the usage of Thermal_control_data include: •All thermal examples |
 | Control_title Control data name |
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Control data name (maximum 64 characters).
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| Solution_algorithm Solution algorithm for thermal field |
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Specifies the solution algorithm to be used for solving the thermal field, valid values are: • 1 - linear static • 2 - nonlinear static • 3 - linear transient • 4 - nonlinear transient (default)
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| Initial_time Initial time for the analysis (default 0.0) |
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Specifies that the simulation starts from a specific reference time. Generally Initial_time is not specified and is set to 0.0 by default
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| Initial_time_step Initial time step |
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Defines the time step length for first time step of the control stage. The initial time step length must always be specified.
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| Time_step_growth Time step growth in the implicit mechanical field |
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Defines the time step growth between successive increments in the mechanical field specified as a factor; i.e. Δtnext =fgrowthΔtcurr where fgrowth is the growth factor ( fgrowth > 1).
Generally the default value is adequate and this parameter does not need to be specified.
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| Maximum_time_step_growth Maximum time step change |
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Defines the maximum time step growth between successive increments specified as a factor; i.e. Δtnext ≤ fgrowthΔtcurr where fgrowth is the growth factor ( fgrowth > 1) with a default value of unlimited growth
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| Minimum_time_step Minimum time step that terminates the analysis |
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Defines the minimum time step that terminates the analysis.
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| Maximum_time_step Maximum allowable time step |
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Defines the maximum allowable time step size.
Notes •Maximum_time_step is only required if variable time step is used. •By default the maximum time step size is unbounded.
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| Maximum_number_time_steps Maximum number of steps for control |
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Defines the maximum number of steps for control stage (Default: 1E8)
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| Termination_time Termination time for control |
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Defines the termination time for the current control stage. This is the absolute termination time rather than the duration.
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| Duration The duration for the control step |
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Defines the duration for the current control stage. If the duration is specified then the Termination time for the current control stage is automatically set to the current time + the duration
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| Maximum_number_iterations Maximum number of iterations for a time step |
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Defines the maximum number of iterations for a time step (Default: 15). If the maximum value is reached the simulation will be terminated.
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| Target_number_iterations Target optimal number of iterations |
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Defines the target optimal number of iterations. This parameter indicates that variable time step is required and also controls the time step size. The variable time step algorithm chooses the time step based on the expression:
where Δtcurr is the current time step, Δtnext is the time step for the next step, Ntarget is the target number of iterations and Ncurr is the number of iterations required for the current step.
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| Temperature_tolerance Tolerance for temperature convergence using incremental values |
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Defines the tolerance for temperature convergence using incremental and total values; i.e.
Notes •The default value is 0.01%
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| Temperature_total_tolerance Tolerance for temperature convergence using total values |
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Defines the tolerance for temperature convergence using incremental and total values; i.e.
Notes •The default value is 0.01%
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| Residual_norm_tolerance Tolerance for residual convergence |
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The tolerance for the residual flux is defined as:
Notes •The default value is 0.0001%
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| Max_number_timestep_cuts Max_number_timestep_cuts |
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Time step cutting can be used to repeat the current time step with a smaller step length if convergence with the current step length cannot be achieved. The maximum number of time step cuts specifies the number of times a time step can be cut before the analysis should be terminated. Each time step cut reduces the the time step length by 50%, so that the default value of max_number_timestep_cut of 3 terminates if convergence cannot be achieved with a time step of 12.5% of the initial value.
Notes •The default value of 3 is generally the best option. More than 3 time step cuts would imply a sudden large drop (ca. 90%) in the acceptable time step length
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| Output_frequency_plotfile Output step frequency to plot file |
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Defines the number of time steps between output of results to the plot file. If a value of - 1 is specified then output will be performed at the end of the control stage. Note that if Output_frequency_plotfile is not defined no plot file will be output based on time steps/ increments nor at the end of stage.
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| Output_time_plotfile Output time frequency to plot file |
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Defines the time between output of data to the plot file (Default 0.0 - No output based on time).
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| Screen_message_frequency Output step frequency to screen |
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Defines the number of time steps between output of the log file data to the screen. If a value of - 1 is specified then output will be performed at the end of the control stage.
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| Screen_message_time Output time frequency to screen |
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Defines the time between output of log data to the screen (Default 0.0 - No output based on time)
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| Output_frequency_restart Output step frequency to restart file |
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Defines the number of time steps between output of results to the restart file named ModelName.rst . If a value of - 1 is specified then output will be performed at the end of the control stage to the restart file named ModelName_stage_No.rst , where No is the number of control stage within the analysis. (Default /k1 Output_frequency_restart = - 1)
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| Output_time_restart Output time frequency to restart file |
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Defines the time between output of data to the restart file named ModelName.rst . (Default 0.0 - No output based on time).
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| Symmetric_solver_flag Symmetric solver flag |
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Flag indicating whether a symmetric or non-symmetric solver should be used for the thermal field. Generally this value is not defined by the user and is automatically evaluated. Valid values are: • 0 - non symmetric solver • 1 - symmetric solver
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