Case02 Implicit Initialization

 

The present case demonstrates how to use the implicit solver for the two initial initialization stages (gravity initialization and tectonic displacement). The initialization stages accounting for contact release and constitutive release need to be run with the explicit solver as the implicit solver cannot be used for non-linear materials/contact.

 

The initial conditions, material properties and boundary conditions are identical to Case01 and only difference is usage of the implicit solver for the first two stages. It should be noted that the only difference in the data set up for running the implicit solver is in Control_data. The workflow consists of two steps:

 

1.Definition of a datafile for the first two stages using the implicit solver. A restart file (.rst) must be output at the end of the second stage.

2.A restart datafile is defined to start from the results after the implicit initialization stage.

 

The data files are in MEM_001\Case02\Data.

 

 

 

Implicit Initialization

 

The Control_data set up for running the initialization stages using the implicit solver is shown below.

 

Data File

 

* Control_data

! ====================================

 Control_title           "Tectonic"

Solution_algorithm               7

 Duration                       1.0

 Initial_time_increment         1.0

 Displacement_norm_tolerance   0.01

 Residual_norm_tolerance       0.01  

 Output_frequency_plotfile       -1

 Screen_message_frequency         1

 Output_frequency_restart        -1

 

1.Solution_algorithm set to option 7 indicates usage of the implicit solver for the geomechanical field

2.Definition of Displacement_norm_tolerance and Residual_norm_tolerance is compulsory.

3.Definition of Initial_time_increment indicating the time step size is compulsory.

4.Output_frequency_restart set to -1 must be specified in order to allow restart and continuation of the simulation using the explicit solver.

 

 

 

 

Explicit Stages

 

Nothing special needs to be defined to continue the simulation with the explicit solver. Only definition of Restart_read_data and appropriate Control_data for the explicit solver is required. The data is identical to Case01.

 

 

Restart_read_data

 

Data File

 

* Restart_read_data

! ----------------------------------------

 Restart_file_name      MEM_001_Case02_stage_02.rst

 

1.Restart_read_data is defined to read the state at the end of the tectonic initialization stage and enable to continue the simulation from this point using the explicit solver.

 

 

 

 

Control_data

 

Data File

 

* Control_data

! =====================================

  Control_title           "Release"

  Solution_algorithm               1

  Duration                       1.0

  Target_number_time_steps     10000

  Output_frequency_plotfile       -1

  Output_time_plotfile           0.2

  Output_frequency_restart        -1

  Screen_message_frequency      1000

 

1.The usual data for the geomechanical field using the explicit solver is defined in Control_data.

 

 

 

 

 

Results

 

The results are in MEM_001\Case02\Results. These are not discussed as they are similar to Case01 results.

 

Comparison of the CPU time reported in the .res file for solving the two first initialization stages using the explicit and the implicit solvers is shown below. Note that the simulation has been run sequentially.

 

Explicit

Implicit

124 s

4 s