Namelist "Simulation_Management"

This data setup allows the user to set the time parameters of the code in order to :

perform the numerical simulation (time step, stopping criteria…)

record the results associated to time series of probes, instantaneous physical quantity fields, statistical quantities.

record the backup/restart files

Full data set of the namelist

&Simulation_Management Restart_Parameter= 0 ,
Steady_Flow_Stopping_Criterion_Enabled = .false. ,
Steady_Flow_Stopping_Criterion = 1.D-20,
Temporal_Iterations_Number = 10 ,
Final_Time = 3.D+01 ,
TimeStep_Type = 0 ,
Timestep_Min = 1.D-03 ,
Timestep_Max = 1.D-03 ,
CFL_Min = 0.5 ,
CFL_Max = 0.5 ,
Iterations_For_Timestep_Linear_Progress= 1,
Simulation_Backup_Rate = 1000 ,
Simulation_Checking_Rate = 200 ,
Fields_Recording_Rate = 1.D+00 ,
Probe_Recording_Rate = 10 ,
Start_Time_For_Statistics= 1.D+2 ,
Time_Range_Statistic_Calculation = 1.D+00 /

Definition of the data set

Restart the simulation

Restart_Parameter

Type : Integer Value

This data indicates how is initialized the simulation :

0 : The simulation starts from the beginning corresponding to an initialization state.

1 or 2 : The simulation is resumed from a temporary backup file recorded during the previous simulation. Useful to resume a simulation suddenly interrupted. As the temporary backup file a regularly removed during a simulation, only the two last files created by the code are available. They correspond to the number 1 or 2. The number of last file created is recorded in the file num_sav_xxxxx.d (xxxxx correspond to the MPI process number when the simulation is performed in a domain decomposition approach).

3 : The simulation is resumed from the last backup file built during the last time step of the previous simulation. Useful to continue a incompleted simulation. The number 3 must be present in the file num_sav_xxxxx.d (proof that the previous simulation is correctly completed), otherwise the numbers 0, 1 or 2 (related to the previous cases) will be present.

Stopping criteria

Steady_Flow_Stopping_Criterion_Enabled

Type : Boolean value

Activation of the stopping criterion for steady flow (based on the L2-norm of the time variation of physical quantities).

Steady_Flow_Stopping_Criterion

Type : Real value

When the L2-norm of the time variation of physical quantities is lower than this value, the simulation is stopped and the solution corresponds to a steady flow.

Number_Temporal_Iterations

Type : Integer value

This value is the maximum of time iterations performed by the code before stopping.

Final_Time

Type : Real value

This value is the physical time limit reached by the simulation before stopping.

The simulation stops as soon as one of these conditions is achieved.

Numerical time step

TimeStep_Type

Type : Integer value

Selection of way to define the numerical time step :

0 : The time step is constant and defined by the user by means of the variable “Timestep_max” (see further).

-1 : The time step evolves lineraly between the values given by “Timestep_min” and “Timestep_max”. The range of variation is defined by the variable “Iterations_For_Timestep_Linear_Progress” (in time iteration number, see further).

1 : The time step is calculated for each time iteration by means of the CFL parameter. The CFL parameter can be constant, it is thus defined by the variable “CFL_Max”.
It can also evolve linearly between the values given by “CFL_Min” and “CFL_Max”. The range of variation is defined by the variable “Iterations_For_Timestep_Linear_Progress” (in time iteration number, see further).

Timestep_min

Type : Real value

Minimum value of the time step. This variable can be omitted when the time step is constant.

Timestep_max

Type : Real value

Maximum value of the time step. This variable set the value of the time step when it is constant.

CFL_min

Type : Real value. This variable can be omitted when the time step is constant.

Minimum value of the CFL parameter (can be omitted, in this case CFL_Max will define the CFL value).

CFL_max

Type : Real value

Maximum value of the CFL parameter. This variable set the value of the CFL parameter when it is constant (in this case, CFL_Min is useless).

Iterations_For_Timestep_Linear_Progress

Type : Integer value

Number of time iterations over which the CFL parameter or the time step can evolve linearly. When the time step or the CFL parameter are constant, this variable must not set to a value greater than 1. It could actually be omitted (this default value is 1).

For a dynamic computation of the time step from a CFL condition, you can only set the variable CFL_Max if you want a constant CFL value and CFL_Min can be omitted. In any way, the maximum value the time step can reached is limited by the value of Timestep_max (useful when the initial condition is defined from a zero velocity field for which the time step cannot be computed from the CFL condition).

Recording rates for different kind of files

- For backup/restart files :

Simulation_Backup_Rate

Type : Integer value

This variable defines the recording rate, in time iteration units , of the backup files (for instance, when “Simulation_Backup_Rate=1000” a data backup is carried out for all time iteration numbers that are a multiple of 1000).
Backup data are dispatched in two files that are named save_var_yyyyy_n.d and save_fld_yyyyy_n.d ('yyyyy' is the subdomain number for simulations based on the MPI domain-decomposition approach, n= 1 or 2 for temporary backup files and n=3 for the backup files created during the last time step of the simulation).

- For snapshot files :

Field_Recording_Rate

Type : Real value

This variable defines the recording rate, in time units , of instantaneous fields (for instance, when “Field_Recording_Rate=1.5” an instantaneous field file is created as soon as the time value is a multiple of 1.5).
Instantaneous field files are named res_xxxxxxx_yyyyy.d ('yyyyy' is the subdomain number for simulations based on the MPI domain-decomposition approach, 'xxxxxxx' is the file number). The intantaneous fields of the physical quantities are defined with the namelist “Instantaneous_Fields_Listing”.

InstantaneousFields_RecordingStartTime

Type : Real value

This variable sets the time threshold from which the record of instantaneous fields begins. It must be used along with the next variable “InstantaneousFields_TimeRecordingRate”. This value is defined in time units.

InstantaneousFields_TimeRecordingRate

Type : Real value

This variable defines the recording rate, in time units , of instantaneous fields. For instance, when “InstantaneousFields_TimeRecordingRate=1.5” a file is created at every 1.5 time units from the start time provided by the variable “InstantaneousFields_RecordingStartTime”.

InstantaneousFields_StartTimeIterationRecording

Type : Integer value

This variable sets the time-iteration threshold from which the record of instantaneous fields begins. It must be used along with the next variable “InstantaneousFields_TimeIterationRecordingRate”. This value is defined in time-iteration units (number of time steps).

InstantaneousFields_TimeIterationRecordingRate

Type : Integer value

This variable defines the recording rate, in time-iteration units , of instantaneous fields. For instance, when “InstantaneousFields_TimeIterationRecordingRate=100” a file is created at every 100 time steps from the threshold provided by the variable “InstantaneousFields_StartTimeIterationRecording”.

InstantaneousFields_RecordingReset

Type : Boolean value

When this variable is set to “true”, the ID number of file 'xxxxxxx' is set to zero for the next simulation.

Keep in mind : Instantaneous field files are named res_xxxxxxx_yyyyy.d. T The number 'yyyyy' stands for the subdomain number on which fields are recorded for simulations based on the MPI domain-decomposition approach. When the domain decomposition approach is not used (just one domain), 'yyyyy=00000' is the default value. 'xxxxxxx' is the ID number of the file. 'xxxxxxx' is incremented by one for each new file created. The intantaneous fields of the physical quantities written in each file are defined with the namelist “Instantaneous_Fields_Listing”.

- For statistics files :

Start_Time_For_Statistics

Type : Real value

Time from which the statistical fields are calculated.

Time_Range_Statistic_Calculation

Type : Real value

Time range over which statistical fields are calculated. When this time range has been covered, statistical fields are recorded in a file named rst_xxxxxxx_yyyyy.d ('yyyyy' is the subdomain number for simulations based on the MPI domain-decomposition approach, 'xxxxxxx' is the file number). If the simulation is not completed a new cycle of statistical calculation is initialized. The statistical quantities are defined with the namelist “Statistical_Fields_Listing”.

- For probe time-series files :

Probe_Recording_Rate

Type : Integer value

This variable defines the recording rate, in time iteration units , of time series associated to the probes distributed over the domain (see the namelist “Probe_Location”). The physical quantities linked to the probe time-series are defined with the namelist “Probe_Quantities_Enabled”. For instance, when “Probe_Recording_Rate=10”, a new value is added to probe time-series for all time iteration numbers that are a multiple of 10).