schema_implicite_base

Inherits from: schema_temps_base

Basic class for implicite time scheme.

Parameters:

[max_iter_implicite] (type: int) Maximum number of iterations allowed for the solver (by default 200).
solveur (type: solveur_implicite_base) This keyword is used to designate the solver selected in the situation where the time scheme is an implicit scheme. solver is the name of the solver that allows equation diffusion and convection operators to be set as implicit terms. Keywords corresponding to this functionality are Simple (SIMPLE type algorithm), Simpler (SIMPLER type algorithm) for incompressible systems, Piso (Pressure Implicit with Split Operator), and Implicite (similar to PISO, but as it looks like a simplified solver, it will use fewer timesteps, and ICE (for PB_multiphase). But it may run faster because the pressure matrix is not re-assembled and thus provides CPU gains. Advice: Since the 1.6.0 version, we recommend to use first the Implicite or Simple, then Piso, and at least Simpler. Because the two first give a fastest convergence (several times) than Piso and the Simpler has not been validated. It seems also than Implicite and Piso schemes give better results than the Simple scheme when the flow is not fully stationary. Thus, if the solution obtained with Simple is not stationary, it is recommended to switch to Piso or Implicite scheme.
[tinit] (type: float) Value of initial calculation time (0 by default).
[tmax] (type: float) Time during which the calculation will be stopped (1e30s by default).
[tcpumax] (type: float) CPU time limit (must be specified in hours) for which the calculation is stopped (1e30s by default).
[dt_min] (type: float) Minimum calculation time step (1e-16s by default).
[dt_max] (type: string) Maximum calculation time step as function of time (1e30s by default).
[dt_sauv] (type: float) Save time step value (1e30s by default). Every dt_sauv, fields are saved in the .sauv file. The file contains all the information saved over time. If this instruction is not entered, results are saved only upon calculation completion. To disable the writing of the .sauv files, you must specify 0. Note that dt_sauv is in terms of physical time (not cpu time).
[nb_sauv_max] (type: int) Maximum number of timesteps that will be stored in backup file (10 by default). This value is only useful when doing a complete backup of the calculation with parallel PDI (as it needs to allocate the proper amount of dataspace in advance). If this number is reached (ie we already stored the data of nb_sauv_max timesteps in the file), the next checkpoints will overwrite the first ones
[dt_impr] (type: float) Scheme parameter printing time step in time (1e30s by default). The time steps and the flux balances are printed (incorporated onto every side of processed domains) into the .out file.
[facsec] (type: string) Value assigned to the safety factor for the time step (1. by default). It can also be a function of time. The time step calculated is multiplied by the safety factor. The first thing to try when a calculation does not converge with an explicit time scheme is to reduce the facsec to 0.5. Warning: Some schemes needs a facsec lower than 1 (0.5 is a good start), for example Schema_Adams_Bashforth_order_3.
[seuil_statio] (type: float) Value of the convergence threshold (1e-12 by default). Problems using this type of time scheme converge when the derivatives dGi/dt of all the unknown transported values Gi have a combined absolute value less than this value. This is the keyword used to set the permanent rating threshold.
[residuals] (type: residuals) To specify how the residuals will be computed (default max norm, possible to choose L2-norm instead).
[diffusion_implicite] (type: int) Keyword to make the diffusive term in the Navier-Stokes equations implicit (in this case, it should be set to 1). The stability time step is then only based on the convection time step (dt=facsec*dt_convection). Thus, in some circumstances, an important gain is achieved with respect to the time step (large diffusion with respect to convection on tightened meshes). Caution: It is however recommended that the user avoids exceeding the convection time step by selecting a too large facsec value. Start with a facsec value of 1 and then increase it gradually if you wish to accelerate calculation. In addition, for a natural convection calculation with a zero initial velocity, in the first time step, the convection time is infinite and therefore dt=facsec*dt_max.
[seuil_diffusion_implicite] (type: float) This keyword changes the default value (1e-6) of convergency criteria for the resolution by conjugate gradient used for implicit diffusion.
[impr_diffusion_implicite] (type: int) Unactivate (default) or not the printing of the convergence during the resolution of the conjugate gradient.
[impr_extremums] (type: int) Print unknowns extremas
[no_error_if_not_converged_diffusion_implicite] (type: int) not_set
[no_conv_subiteration_diffusion_implicite] (type: int) not_set
[dt_start] (type: dt_start) dt_start dt_min : the first iteration is based on dt_min. dt_start dt_calc : the time step at first iteration is calculated in agreement with CFL condition. dt_start dt_fixe value : the first time step is fixed by the user (recommended when resuming calculation with Crank Nicholson temporal scheme to ensure continuity). By default, the first iteration is based on dt_calc.
[nb_pas_dt_max] (type: int) Maximum number of calculation time steps (1e9 by default).
[niter_max_diffusion_implicite] (type: int) This keyword changes the default value (number of unknowns) of the maximal iterations number in the conjugate gradient method used for implicit diffusion.
[precision_impr] (type: int) Optional keyword to define the digit number for flux values printed into .out files (by default 3).
[periode_sauvegarde_securite_en_heures] (type: float) To change the default period (23 hours) between the save of the fields in .sauv file.
[no_check_disk_space] (type: flag) To disable the check of the available amount of disk space during the calculation.
[disable_progress] (type: flag) To disable the writing of the .progress file.
[disable_dt_ev] (type: flag) To disable the writing of the .dt_ev file.
[adapt_dt_tmax] (type: flag) Use to adapt final dt when approaching tmax.
[gnuplot_header] (type: int) Optional keyword to modify the header of the .out files. Allows to use the column title instead of columns number.

schema_adams_moulton_order_2

Inherits from: schema_implicite_base

not_set

Parameters:

[facsec_max] (type: float) Maximum ratio allowed between time step and stability time returned by CFL condition. The initial ratio given by facsec keyword is changed during the calculation with the implicit scheme but it couldn\'t be higher than facsec_max value. Warning: Some implicit schemes do not permit high facsec_max, example Schema_Adams_Moulton_order_3 needs facsec=facsec_max=1. Advice: The calculation may start with a facsec specified by the user and increased by the algorithm up to the facsec_max limit. But the user can also choose to specify a constant facsec (facsec_max will be set to facsec value then). Faster convergence has been seen and depends on the kind of calculation: -Hydraulic only or thermal hydraulic with forced convection and low coupling between velocity and temperature (Boussinesq value beta low), facsec between 20-30-Thermal hydraulic with forced convection and strong coupling between velocity and temperature (Boussinesq value beta high), facsec between 90-100 -Thermohydralic with natural convection, facsec around 300 -Conduction only, facsec can be set to a very high value (1e8) as if the scheme was unconditionally stableThese values can also be used as rule of thumb for initial facsec with a facsec_max limit higher.
[max_iter_implicite] (type: int) Maximum number of iterations allowed for the solver (by default 200).
solveur (type: solveur_implicite_base) This keyword is used to designate the solver selected in the situation where the time scheme is an implicit scheme. solver is the name of the solver that allows equation diffusion and convection operators to be set as implicit terms. Keywords corresponding to this functionality are Simple (SIMPLE type algorithm), Simpler (SIMPLER type algorithm) for incompressible systems, Piso (Pressure Implicit with Split Operator), and Implicite (similar to PISO, but as it looks like a simplified solver, it will use fewer timesteps, and ICE (for PB_multiphase). But it may run faster because the pressure matrix is not re-assembled and thus provides CPU gains. Advice: Since the 1.6.0 version, we recommend to use first the Implicite or Simple, then Piso, and at least Simpler. Because the two first give a fastest convergence (several times) than Piso and the Simpler has not been validated. It seems also than Implicite and Piso schemes give better results than the Simple scheme when the flow is not fully stationary. Thus, if the solution obtained with Simple is not stationary, it is recommended to switch to Piso or Implicite scheme.
[tinit] (type: float) Value of initial calculation time (0 by default).
[tmax] (type: float) Time during which the calculation will be stopped (1e30s by default).
[tcpumax] (type: float) CPU time limit (must be specified in hours) for which the calculation is stopped (1e30s by default).
[dt_min] (type: float) Minimum calculation time step (1e-16s by default).
[dt_max] (type: string) Maximum calculation time step as function of time (1e30s by default).
[dt_sauv] (type: float) Save time step value (1e30s by default). Every dt_sauv, fields are saved in the .sauv file. The file contains all the information saved over time. If this instruction is not entered, results are saved only upon calculation completion. To disable the writing of the .sauv files, you must specify 0. Note that dt_sauv is in terms of physical time (not cpu time).
[nb_sauv_max] (type: int) Maximum number of timesteps that will be stored in backup file (10 by default). This value is only useful when doing a complete backup of the calculation with parallel PDI (as it needs to allocate the proper amount of dataspace in advance). If this number is reached (ie we already stored the data of nb_sauv_max timesteps in the file), the next checkpoints will overwrite the first ones
[dt_impr] (type: float) Scheme parameter printing time step in time (1e30s by default). The time steps and the flux balances are printed (incorporated onto every side of processed domains) into the .out file.
[facsec] (type: string) Value assigned to the safety factor for the time step (1. by default). It can also be a function of time. The time step calculated is multiplied by the safety factor. The first thing to try when a calculation does not converge with an explicit time scheme is to reduce the facsec to 0.5. Warning: Some schemes needs a facsec lower than 1 (0.5 is a good start), for example Schema_Adams_Bashforth_order_3.
[seuil_statio] (type: float) Value of the convergence threshold (1e-12 by default). Problems using this type of time scheme converge when the derivatives dGi/dt of all the unknown transported values Gi have a combined absolute value less than this value. This is the keyword used to set the permanent rating threshold.
[residuals] (type: residuals) To specify how the residuals will be computed (default max norm, possible to choose L2-norm instead).
[diffusion_implicite] (type: int) Keyword to make the diffusive term in the Navier-Stokes equations implicit (in this case, it should be set to 1). The stability time step is then only based on the convection time step (dt=facsec*dt_convection). Thus, in some circumstances, an important gain is achieved with respect to the time step (large diffusion with respect to convection on tightened meshes). Caution: It is however recommended that the user avoids exceeding the convection time step by selecting a too large facsec value. Start with a facsec value of 1 and then increase it gradually if you wish to accelerate calculation. In addition, for a natural convection calculation with a zero initial velocity, in the first time step, the convection time is infinite and therefore dt=facsec*dt_max.
[seuil_diffusion_implicite] (type: float) This keyword changes the default value (1e-6) of convergency criteria for the resolution by conjugate gradient used for implicit diffusion.
[impr_diffusion_implicite] (type: int) Unactivate (default) or not the printing of the convergence during the resolution of the conjugate gradient.
[impr_extremums] (type: int) Print unknowns extremas
[no_error_if_not_converged_diffusion_implicite] (type: int) not_set
[no_conv_subiteration_diffusion_implicite] (type: int) not_set
[dt_start] (type: dt_start) dt_start dt_min : the first iteration is based on dt_min. dt_start dt_calc : the time step at first iteration is calculated in agreement with CFL condition. dt_start dt_fixe value : the first time step is fixed by the user (recommended when resuming calculation with Crank Nicholson temporal scheme to ensure continuity). By default, the first iteration is based on dt_calc.
[nb_pas_dt_max] (type: int) Maximum number of calculation time steps (1e9 by default).
[niter_max_diffusion_implicite] (type: int) This keyword changes the default value (number of unknowns) of the maximal iterations number in the conjugate gradient method used for implicit diffusion.
[precision_impr] (type: int) Optional keyword to define the digit number for flux values printed into .out files (by default 3).
[periode_sauvegarde_securite_en_heures] (type: float) To change the default period (23 hours) between the save of the fields in .sauv file.
[no_check_disk_space] (type: flag) To disable the check of the available amount of disk space during the calculation.
[disable_progress] (type: flag) To disable the writing of the .progress file.
[disable_dt_ev] (type: flag) To disable the writing of the .dt_ev file.
[adapt_dt_tmax] (type: flag) Use to adapt final dt when approaching tmax.
[gnuplot_header] (type: int) Optional keyword to modify the header of the .out files. Allows to use the column title instead of columns number.

schema_adams_moulton_order_3

Inherits from: schema_implicite_base

not_set

Parameters:

[facsec_max] (type: float) Maximum ratio allowed between time step and stability time returned by CFL condition. The initial ratio given by facsec keyword is changed during the calculation with the implicit scheme but it couldn\'t be higher than facsec_max value. Warning: Some implicit schemes do not permit high facsec_max, example Schema_Adams_Moulton_order_3 needs facsec=facsec_max=1. Advice: The calculation may start with a facsec specified by the user and increased by the algorithm up to the facsec_max limit. But the user can also choose to specify a constant facsec (facsec_max will be set to facsec value then). Faster convergence has been seen and depends on the kind of calculation: -Hydraulic only or thermal hydraulic with forced convection and low coupling between velocity and temperature (Boussinesq value beta low), facsec between 20-30-Thermal hydraulic with forced convection and strong coupling between velocity and temperature (Boussinesq value beta high), facsec between 90-100 -Thermohydralic with natural convection, facsec around 300 -Conduction only, facsec can be set to a very high value (1e8) as if the scheme was unconditionally stableThese values can also be used as rule of thumb for initial facsec with a facsec_max limit higher.
[max_iter_implicite] (type: int) Maximum number of iterations allowed for the solver (by default 200).
solveur (type: solveur_implicite_base) This keyword is used to designate the solver selected in the situation where the time scheme is an implicit scheme. solver is the name of the solver that allows equation diffusion and convection operators to be set as implicit terms. Keywords corresponding to this functionality are Simple (SIMPLE type algorithm), Simpler (SIMPLER type algorithm) for incompressible systems, Piso (Pressure Implicit with Split Operator), and Implicite (similar to PISO, but as it looks like a simplified solver, it will use fewer timesteps, and ICE (for PB_multiphase). But it may run faster because the pressure matrix is not re-assembled and thus provides CPU gains. Advice: Since the 1.6.0 version, we recommend to use first the Implicite or Simple, then Piso, and at least Simpler. Because the two first give a fastest convergence (several times) than Piso and the Simpler has not been validated. It seems also than Implicite and Piso schemes give better results than the Simple scheme when the flow is not fully stationary. Thus, if the solution obtained with Simple is not stationary, it is recommended to switch to Piso or Implicite scheme.
[tinit] (type: float) Value of initial calculation time (0 by default).
[tmax] (type: float) Time during which the calculation will be stopped (1e30s by default).
[tcpumax] (type: float) CPU time limit (must be specified in hours) for which the calculation is stopped (1e30s by default).
[dt_min] (type: float) Minimum calculation time step (1e-16s by default).
[dt_max] (type: string) Maximum calculation time step as function of time (1e30s by default).
[dt_sauv] (type: float) Save time step value (1e30s by default). Every dt_sauv, fields are saved in the .sauv file. The file contains all the information saved over time. If this instruction is not entered, results are saved only upon calculation completion. To disable the writing of the .sauv files, you must specify 0. Note that dt_sauv is in terms of physical time (not cpu time).
[nb_sauv_max] (type: int) Maximum number of timesteps that will be stored in backup file (10 by default). This value is only useful when doing a complete backup of the calculation with parallel PDI (as it needs to allocate the proper amount of dataspace in advance). If this number is reached (ie we already stored the data of nb_sauv_max timesteps in the file), the next checkpoints will overwrite the first ones
[dt_impr] (type: float) Scheme parameter printing time step in time (1e30s by default). The time steps and the flux balances are printed (incorporated onto every side of processed domains) into the .out file.
[facsec] (type: string) Value assigned to the safety factor for the time step (1. by default). It can also be a function of time. The time step calculated is multiplied by the safety factor. The first thing to try when a calculation does not converge with an explicit time scheme is to reduce the facsec to 0.5. Warning: Some schemes needs a facsec lower than 1 (0.5 is a good start), for example Schema_Adams_Bashforth_order_3.
[seuil_statio] (type: float) Value of the convergence threshold (1e-12 by default). Problems using this type of time scheme converge when the derivatives dGi/dt of all the unknown transported values Gi have a combined absolute value less than this value. This is the keyword used to set the permanent rating threshold.
[residuals] (type: residuals) To specify how the residuals will be computed (default max norm, possible to choose L2-norm instead).
[diffusion_implicite] (type: int) Keyword to make the diffusive term in the Navier-Stokes equations implicit (in this case, it should be set to 1). The stability time step is then only based on the convection time step (dt=facsec*dt_convection). Thus, in some circumstances, an important gain is achieved with respect to the time step (large diffusion with respect to convection on tightened meshes). Caution: It is however recommended that the user avoids exceeding the convection time step by selecting a too large facsec value. Start with a facsec value of 1 and then increase it gradually if you wish to accelerate calculation. In addition, for a natural convection calculation with a zero initial velocity, in the first time step, the convection time is infinite and therefore dt=facsec*dt_max.
[seuil_diffusion_implicite] (type: float) This keyword changes the default value (1e-6) of convergency criteria for the resolution by conjugate gradient used for implicit diffusion.
[impr_diffusion_implicite] (type: int) Unactivate (default) or not the printing of the convergence during the resolution of the conjugate gradient.
[impr_extremums] (type: int) Print unknowns extremas
[no_error_if_not_converged_diffusion_implicite] (type: int) not_set
[no_conv_subiteration_diffusion_implicite] (type: int) not_set
[dt_start] (type: dt_start) dt_start dt_min : the first iteration is based on dt_min. dt_start dt_calc : the time step at first iteration is calculated in agreement with CFL condition. dt_start dt_fixe value : the first time step is fixed by the user (recommended when resuming calculation with Crank Nicholson temporal scheme to ensure continuity). By default, the first iteration is based on dt_calc.
[nb_pas_dt_max] (type: int) Maximum number of calculation time steps (1e9 by default).
[niter_max_diffusion_implicite] (type: int) This keyword changes the default value (number of unknowns) of the maximal iterations number in the conjugate gradient method used for implicit diffusion.
[precision_impr] (type: int) Optional keyword to define the digit number for flux values printed into .out files (by default 3).
[periode_sauvegarde_securite_en_heures] (type: float) To change the default period (23 hours) between the save of the fields in .sauv file.
[no_check_disk_space] (type: flag) To disable the check of the available amount of disk space during the calculation.
[disable_progress] (type: flag) To disable the writing of the .progress file.
[disable_dt_ev] (type: flag) To disable the writing of the .dt_ev file.
[adapt_dt_tmax] (type: flag) Use to adapt final dt when approaching tmax.
[gnuplot_header] (type: int) Optional keyword to modify the header of the .out files. Allows to use the column title instead of columns number.

schema_backward_differentiation_order_2

Inherits from: schema_implicite_base

not_set

Parameters:

[facsec_max] (type: float) Maximum ratio allowed between time step and stability time returned by CFL condition. The initial ratio given by facsec keyword is changed during the calculation with the implicit scheme but it couldn\'t be higher than facsec_max value. Warning: Some implicit schemes do not permit high facsec_max, example Schema_Adams_Moulton_order_3 needs facsec=facsec_max=1. Advice: The calculation may start with a facsec specified by the user and increased by the algorithm up to the facsec_max limit. But the user can also choose to specify a constant facsec (facsec_max will be set to facsec value then). Faster convergence has been seen and depends on the kind of calculation: -Hydraulic only or thermal hydraulic with forced convection and low coupling between velocity and temperature (Boussinesq value beta low), facsec between 20-30-Thermal hydraulic with forced convection and strong coupling between velocity and temperature (Boussinesq value beta high), facsec between 90-100 -Thermohydralic with natural convection, facsec around 300 -Conduction only, facsec can be set to a very high value (1e8) as if the scheme was unconditionally stableThese values can also be used as rule of thumb for initial facsec with a facsec_max limit higher.
[max_iter_implicite] (type: int) Maximum number of iterations allowed for the solver (by default 200).
solveur (type: solveur_implicite_base) This keyword is used to designate the solver selected in the situation where the time scheme is an implicit scheme. solver is the name of the solver that allows equation diffusion and convection operators to be set as implicit terms. Keywords corresponding to this functionality are Simple (SIMPLE type algorithm), Simpler (SIMPLER type algorithm) for incompressible systems, Piso (Pressure Implicit with Split Operator), and Implicite (similar to PISO, but as it looks like a simplified solver, it will use fewer timesteps, and ICE (for PB_multiphase). But it may run faster because the pressure matrix is not re-assembled and thus provides CPU gains. Advice: Since the 1.6.0 version, we recommend to use first the Implicite or Simple, then Piso, and at least Simpler. Because the two first give a fastest convergence (several times) than Piso and the Simpler has not been validated. It seems also than Implicite and Piso schemes give better results than the Simple scheme when the flow is not fully stationary. Thus, if the solution obtained with Simple is not stationary, it is recommended to switch to Piso or Implicite scheme.
[tinit] (type: float) Value of initial calculation time (0 by default).
[tmax] (type: float) Time during which the calculation will be stopped (1e30s by default).
[tcpumax] (type: float) CPU time limit (must be specified in hours) for which the calculation is stopped (1e30s by default).
[dt_min] (type: float) Minimum calculation time step (1e-16s by default).
[dt_max] (type: string) Maximum calculation time step as function of time (1e30s by default).
[dt_sauv] (type: float) Save time step value (1e30s by default). Every dt_sauv, fields are saved in the .sauv file. The file contains all the information saved over time. If this instruction is not entered, results are saved only upon calculation completion. To disable the writing of the .sauv files, you must specify 0. Note that dt_sauv is in terms of physical time (not cpu time).
[nb_sauv_max] (type: int) Maximum number of timesteps that will be stored in backup file (10 by default). This value is only useful when doing a complete backup of the calculation with parallel PDI (as it needs to allocate the proper amount of dataspace in advance). If this number is reached (ie we already stored the data of nb_sauv_max timesteps in the file), the next checkpoints will overwrite the first ones
[dt_impr] (type: float) Scheme parameter printing time step in time (1e30s by default). The time steps and the flux balances are printed (incorporated onto every side of processed domains) into the .out file.
[facsec] (type: string) Value assigned to the safety factor for the time step (1. by default). It can also be a function of time. The time step calculated is multiplied by the safety factor. The first thing to try when a calculation does not converge with an explicit time scheme is to reduce the facsec to 0.5. Warning: Some schemes needs a facsec lower than 1 (0.5 is a good start), for example Schema_Adams_Bashforth_order_3.
[seuil_statio] (type: float) Value of the convergence threshold (1e-12 by default). Problems using this type of time scheme converge when the derivatives dGi/dt of all the unknown transported values Gi have a combined absolute value less than this value. This is the keyword used to set the permanent rating threshold.
[residuals] (type: residuals) To specify how the residuals will be computed (default max norm, possible to choose L2-norm instead).
[diffusion_implicite] (type: int) Keyword to make the diffusive term in the Navier-Stokes equations implicit (in this case, it should be set to 1). The stability time step is then only based on the convection time step (dt=facsec*dt_convection). Thus, in some circumstances, an important gain is achieved with respect to the time step (large diffusion with respect to convection on tightened meshes). Caution: It is however recommended that the user avoids exceeding the convection time step by selecting a too large facsec value. Start with a facsec value of 1 and then increase it gradually if you wish to accelerate calculation. In addition, for a natural convection calculation with a zero initial velocity, in the first time step, the convection time is infinite and therefore dt=facsec*dt_max.
[seuil_diffusion_implicite] (type: float) This keyword changes the default value (1e-6) of convergency criteria for the resolution by conjugate gradient used for implicit diffusion.
[impr_diffusion_implicite] (type: int) Unactivate (default) or not the printing of the convergence during the resolution of the conjugate gradient.
[impr_extremums] (type: int) Print unknowns extremas
[no_error_if_not_converged_diffusion_implicite] (type: int) not_set
[no_conv_subiteration_diffusion_implicite] (type: int) not_set
[dt_start] (type: dt_start) dt_start dt_min : the first iteration is based on dt_min. dt_start dt_calc : the time step at first iteration is calculated in agreement with CFL condition. dt_start dt_fixe value : the first time step is fixed by the user (recommended when resuming calculation with Crank Nicholson temporal scheme to ensure continuity). By default, the first iteration is based on dt_calc.
[nb_pas_dt_max] (type: int) Maximum number of calculation time steps (1e9 by default).
[niter_max_diffusion_implicite] (type: int) This keyword changes the default value (number of unknowns) of the maximal iterations number in the conjugate gradient method used for implicit diffusion.
[precision_impr] (type: int) Optional keyword to define the digit number for flux values printed into .out files (by default 3).
[periode_sauvegarde_securite_en_heures] (type: float) To change the default period (23 hours) between the save of the fields in .sauv file.
[no_check_disk_space] (type: flag) To disable the check of the available amount of disk space during the calculation.
[disable_progress] (type: flag) To disable the writing of the .progress file.
[disable_dt_ev] (type: flag) To disable the writing of the .dt_ev file.
[adapt_dt_tmax] (type: flag) Use to adapt final dt when approaching tmax.
[gnuplot_header] (type: int) Optional keyword to modify the header of the .out files. Allows to use the column title instead of columns number.

schema_backward_differentiation_order_3

Inherits from: schema_implicite_base

not_set

Parameters:

[facsec_max] (type: float) Maximum ratio allowed between time step and stability time returned by CFL condition. The initial ratio given by facsec keyword is changed during the calculation with the implicit scheme but it couldn\'t be higher than facsec_max value. Warning: Some implicit schemes do not permit high facsec_max, example Schema_Adams_Moulton_order_3 needs facsec=facsec_max=1. Advice: The calculation may start with a facsec specified by the user and increased by the algorithm up to the facsec_max limit. But the user can also choose to specify a constant facsec (facsec_max will be set to facsec value then). Faster convergence has been seen and depends on the kind of calculation: -Hydraulic only or thermal hydraulic with forced convection and low coupling between velocity and temperature (Boussinesq value beta low), facsec between 20-30-Thermal hydraulic with forced convection and strong coupling between velocity and temperature (Boussinesq value beta high), facsec between 90-100 -Thermohydralic with natural convection, facsec around 300 -Conduction only, facsec can be set to a very high value (1e8) as if the scheme was unconditionally stableThese values can also be used as rule of thumb for initial facsec with a facsec_max limit higher.
[max_iter_implicite] (type: int) Maximum number of iterations allowed for the solver (by default 200).
solveur (type: solveur_implicite_base) This keyword is used to designate the solver selected in the situation where the time scheme is an implicit scheme. solver is the name of the solver that allows equation diffusion and convection operators to be set as implicit terms. Keywords corresponding to this functionality are Simple (SIMPLE type algorithm), Simpler (SIMPLER type algorithm) for incompressible systems, Piso (Pressure Implicit with Split Operator), and Implicite (similar to PISO, but as it looks like a simplified solver, it will use fewer timesteps, and ICE (for PB_multiphase). But it may run faster because the pressure matrix is not re-assembled and thus provides CPU gains. Advice: Since the 1.6.0 version, we recommend to use first the Implicite or Simple, then Piso, and at least Simpler. Because the two first give a fastest convergence (several times) than Piso and the Simpler has not been validated. It seems also than Implicite and Piso schemes give better results than the Simple scheme when the flow is not fully stationary. Thus, if the solution obtained with Simple is not stationary, it is recommended to switch to Piso or Implicite scheme.
[tinit] (type: float) Value of initial calculation time (0 by default).
[tmax] (type: float) Time during which the calculation will be stopped (1e30s by default).
[tcpumax] (type: float) CPU time limit (must be specified in hours) for which the calculation is stopped (1e30s by default).
[dt_min] (type: float) Minimum calculation time step (1e-16s by default).
[dt_max] (type: string) Maximum calculation time step as function of time (1e30s by default).
[dt_sauv] (type: float) Save time step value (1e30s by default). Every dt_sauv, fields are saved in the .sauv file. The file contains all the information saved over time. If this instruction is not entered, results are saved only upon calculation completion. To disable the writing of the .sauv files, you must specify 0. Note that dt_sauv is in terms of physical time (not cpu time).
[nb_sauv_max] (type: int) Maximum number of timesteps that will be stored in backup file (10 by default). This value is only useful when doing a complete backup of the calculation with parallel PDI (as it needs to allocate the proper amount of dataspace in advance). If this number is reached (ie we already stored the data of nb_sauv_max timesteps in the file), the next checkpoints will overwrite the first ones
[dt_impr] (type: float) Scheme parameter printing time step in time (1e30s by default). The time steps and the flux balances are printed (incorporated onto every side of processed domains) into the .out file.
[facsec] (type: string) Value assigned to the safety factor for the time step (1. by default). It can also be a function of time. The time step calculated is multiplied by the safety factor. The first thing to try when a calculation does not converge with an explicit time scheme is to reduce the facsec to 0.5. Warning: Some schemes needs a facsec lower than 1 (0.5 is a good start), for example Schema_Adams_Bashforth_order_3.
[seuil_statio] (type: float) Value of the convergence threshold (1e-12 by default). Problems using this type of time scheme converge when the derivatives dGi/dt of all the unknown transported values Gi have a combined absolute value less than this value. This is the keyword used to set the permanent rating threshold.
[residuals] (type: residuals) To specify how the residuals will be computed (default max norm, possible to choose L2-norm instead).
[diffusion_implicite] (type: int) Keyword to make the diffusive term in the Navier-Stokes equations implicit (in this case, it should be set to 1). The stability time step is then only based on the convection time step (dt=facsec*dt_convection). Thus, in some circumstances, an important gain is achieved with respect to the time step (large diffusion with respect to convection on tightened meshes). Caution: It is however recommended that the user avoids exceeding the convection time step by selecting a too large facsec value. Start with a facsec value of 1 and then increase it gradually if you wish to accelerate calculation. In addition, for a natural convection calculation with a zero initial velocity, in the first time step, the convection time is infinite and therefore dt=facsec*dt_max.
[seuil_diffusion_implicite] (type: float) This keyword changes the default value (1e-6) of convergency criteria for the resolution by conjugate gradient used for implicit diffusion.
[impr_diffusion_implicite] (type: int) Unactivate (default) or not the printing of the convergence during the resolution of the conjugate gradient.
[impr_extremums] (type: int) Print unknowns extremas
[no_error_if_not_converged_diffusion_implicite] (type: int) not_set
[no_conv_subiteration_diffusion_implicite] (type: int) not_set
[dt_start] (type: dt_start) dt_start dt_min : the first iteration is based on dt_min. dt_start dt_calc : the time step at first iteration is calculated in agreement with CFL condition. dt_start dt_fixe value : the first time step is fixed by the user (recommended when resuming calculation with Crank Nicholson temporal scheme to ensure continuity). By default, the first iteration is based on dt_calc.
[nb_pas_dt_max] (type: int) Maximum number of calculation time steps (1e9 by default).
[niter_max_diffusion_implicite] (type: int) This keyword changes the default value (number of unknowns) of the maximal iterations number in the conjugate gradient method used for implicit diffusion.
[precision_impr] (type: int) Optional keyword to define the digit number for flux values printed into .out files (by default 3).
[periode_sauvegarde_securite_en_heures] (type: float) To change the default period (23 hours) between the save of the fields in .sauv file.
[no_check_disk_space] (type: flag) To disable the check of the available amount of disk space during the calculation.
[disable_progress] (type: flag) To disable the writing of the .progress file.
[disable_dt_ev] (type: flag) To disable the writing of the .dt_ev file.
[adapt_dt_tmax] (type: flag) Use to adapt final dt when approaching tmax.
[gnuplot_header] (type: int) Optional keyword to modify the header of the .out files. Allows to use the column title instead of columns number.

schema_euler_implicite

Synonyms: scheme_euler_implicit

Inherits from: schema_implicite_base

This is the Euler implicit scheme.

Parameters:

[facsec_cfl] (type: flag) Flag to compute time step based on CFL: dt=min(facsec,facsec_max)*dt(convection)X/
[facsec_max] (type: float) For old syntax, see the complete parameters of facsec for details
[facsec_expert] (type: facsec_expert) Advanced facsec specification
[facsec_func] (type: string) Advanced facsec specification as a function
[resolution_monolithique] (type: bloc_lecture) Activate monolithic resolution for coupled problems. Solves together the equations corresponding to the application domains in the given order. All aplication domains of the coupled equations must be given to determine the order of resolution. If the monolithic solving is not wanted for a specific application domain, an underscore can be added as prefix. For example, resolution_monolithique { dom1 { dom2 dom3 } _dom4 } will solve in a single matrix the equations having dom1 as application domain, then the equations having dom2 or dom3 as application domain in a single matrix, then the equations having dom4 as application domain in a sequential way (not in a single matrix).
[max_iter_implicite] (type: int) Maximum number of iterations allowed for the solver (by default 200).
solveur (type: solveur_implicite_base) This keyword is used to designate the solver selected in the situation where the time scheme is an implicit scheme. solver is the name of the solver that allows equation diffusion and convection operators to be set as implicit terms. Keywords corresponding to this functionality are Simple (SIMPLE type algorithm), Simpler (SIMPLER type algorithm) for incompressible systems, Piso (Pressure Implicit with Split Operator), and Implicite (similar to PISO, but as it looks like a simplified solver, it will use fewer timesteps, and ICE (for PB_multiphase). But it may run faster because the pressure matrix is not re-assembled and thus provides CPU gains. Advice: Since the 1.6.0 version, we recommend to use first the Implicite or Simple, then Piso, and at least Simpler. Because the two first give a fastest convergence (several times) than Piso and the Simpler has not been validated. It seems also than Implicite and Piso schemes give better results than the Simple scheme when the flow is not fully stationary. Thus, if the solution obtained with Simple is not stationary, it is recommended to switch to Piso or Implicite scheme.
[tinit] (type: float) Value of initial calculation time (0 by default).
[tmax] (type: float) Time during which the calculation will be stopped (1e30s by default).
[tcpumax] (type: float) CPU time limit (must be specified in hours) for which the calculation is stopped (1e30s by default).
[dt_min] (type: float) Minimum calculation time step (1e-16s by default).
[dt_max] (type: string) Maximum calculation time step as function of time (1e30s by default).
[dt_sauv] (type: float) Save time step value (1e30s by default). Every dt_sauv, fields are saved in the .sauv file. The file contains all the information saved over time. If this instruction is not entered, results are saved only upon calculation completion. To disable the writing of the .sauv files, you must specify 0. Note that dt_sauv is in terms of physical time (not cpu time).
[nb_sauv_max] (type: int) Maximum number of timesteps that will be stored in backup file (10 by default). This value is only useful when doing a complete backup of the calculation with parallel PDI (as it needs to allocate the proper amount of dataspace in advance). If this number is reached (ie we already stored the data of nb_sauv_max timesteps in the file), the next checkpoints will overwrite the first ones
[dt_impr] (type: float) Scheme parameter printing time step in time (1e30s by default). The time steps and the flux balances are printed (incorporated onto every side of processed domains) into the .out file.
[facsec] (type: string) Value assigned to the safety factor for the time step (1. by default). It can also be a function of time. The time step calculated is multiplied by the safety factor. The first thing to try when a calculation does not converge with an explicit time scheme is to reduce the facsec to 0.5. Warning: Some schemes needs a facsec lower than 1 (0.5 is a good start), for example Schema_Adams_Bashforth_order_3.
[seuil_statio] (type: float) Value of the convergence threshold (1e-12 by default). Problems using this type of time scheme converge when the derivatives dGi/dt of all the unknown transported values Gi have a combined absolute value less than this value. This is the keyword used to set the permanent rating threshold.
[residuals] (type: residuals) To specify how the residuals will be computed (default max norm, possible to choose L2-norm instead).
[diffusion_implicite] (type: int) Keyword to make the diffusive term in the Navier-Stokes equations implicit (in this case, it should be set to 1). The stability time step is then only based on the convection time step (dt=facsec*dt_convection). Thus, in some circumstances, an important gain is achieved with respect to the time step (large diffusion with respect to convection on tightened meshes). Caution: It is however recommended that the user avoids exceeding the convection time step by selecting a too large facsec value. Start with a facsec value of 1 and then increase it gradually if you wish to accelerate calculation. In addition, for a natural convection calculation with a zero initial velocity, in the first time step, the convection time is infinite and therefore dt=facsec*dt_max.
[seuil_diffusion_implicite] (type: float) This keyword changes the default value (1e-6) of convergency criteria for the resolution by conjugate gradient used for implicit diffusion.
[impr_diffusion_implicite] (type: int) Unactivate (default) or not the printing of the convergence during the resolution of the conjugate gradient.
[impr_extremums] (type: int) Print unknowns extremas
[no_error_if_not_converged_diffusion_implicite] (type: int) not_set
[no_conv_subiteration_diffusion_implicite] (type: int) not_set
[dt_start] (type: dt_start) dt_start dt_min : the first iteration is based on dt_min. dt_start dt_calc : the time step at first iteration is calculated in agreement with CFL condition. dt_start dt_fixe value : the first time step is fixed by the user (recommended when resuming calculation with Crank Nicholson temporal scheme to ensure continuity). By default, the first iteration is based on dt_calc.
[nb_pas_dt_max] (type: int) Maximum number of calculation time steps (1e9 by default).
[niter_max_diffusion_implicite] (type: int) This keyword changes the default value (number of unknowns) of the maximal iterations number in the conjugate gradient method used for implicit diffusion.
[precision_impr] (type: int) Optional keyword to define the digit number for flux values printed into .out files (by default 3).
[periode_sauvegarde_securite_en_heures] (type: float) To change the default period (23 hours) between the save of the fields in .sauv file.
[no_check_disk_space] (type: flag) To disable the check of the available amount of disk space during the calculation.
[disable_progress] (type: flag) To disable the writing of the .progress file.
[disable_dt_ev] (type: flag) To disable the writing of the .dt_ev file.
[adapt_dt_tmax] (type: flag) Use to adapt final dt when approaching tmax.
[gnuplot_header] (type: int) Optional keyword to modify the header of the .out files. Allows to use the column title instead of columns number.