Solution Control Card Syntax (W)

Character string (e.g., van Genuchten, porosity, m^3/s, Roe Superbee)

Integer (no alpha characters, special characters, or punctuation) (e.g., 1, 32, 195634)

Real (decimal points and exponential notation allowed) (e.g., 0, 0.0, 1.e-12, 1.E+3, 2.345)

Keyword (exact formatting required) (e.g., file, ~Solution Control Card, binary file)

Choose one Execution Mode Option

Normal Option

 Normal,

Restart Option (expects filename to be "restart")

Restart,

Restart Option with specified restart filename

 Restart File,Restart Filename,

One or more (or zero) operational mode modifiers can be specified on the Operational Model Option line

Choose One

Choose one or more optional Operational Mode Modifiers

Solute Transport

...Transport,

Choose One

Choose one or more optional Additional Transport Modifiers

Patankar

...Patankar, (This is the default option - does not need to be specified but can be)

First-Order Upwind

...Upwind,

Leonard-TVD Scheme

...TVD or Leonard,

Roe Superbee

...Roe or Superbee,

Electrolyte

...Electrolyte,

Courant-Number Limited Transport

...Courant,

Vadose Zone Courant-Number Limited Transport

...Vadose Courant,

Reactive Transport

...ECKEChem,

Choose One

Choose one or more optional Additional Reactive Transport Modifiers

Solute Transport

...Transport,

Patankar

...Patankar, (This is the default option - does not need to be specified but can be)

First-Order Upwind

...Upwind,

Leonard-TVD Scheme

...TVD or Leonard,

Roe Superbee

...Roe or Superbee,

Courant-Number Limited Transport

...Courant,

Vadose Zone Courant-Number Limited Transport

...Vadose Courant,

Equilibrium Reduced

...Equilibrium Reduced,

Minimum Concentration

...Minimum Concentration,

Log Concentrations

...Log,

Guess

...Guess,

Porosity Alteration with Precipitation

...Porosity,

Effective Reaction Area

...Area,

Constant Surface Area

...Constant Surface Area,

Note: Keywords are not case sensitive

Repeat for each execution time period

Choose One

Choose one time-step reduction option

Four Successive Time Step Reductions before Execution Stop

Initial Time,Unit(s),Final Time,Unit(s),Initial Time Step,Units,Maximum Time Step,Units,Time Step Acceleration Factor,Maximum number of Newton-Raphson iterations per time step,Convergence Criterion,

Time Step Reductions to Minimum Time Step before Execution Stop

Initial Time,Unit(s),Final Time,Unit(s),Initial Time Step,Units,Maximum Time Step,Units,Time Step Acceleration Factor,Maximum number of Newton-Raphson iterations per time step,Convergence Criterion,Minimum Time Step,Units,Time Step Reduction Factor,

Execution Time periods

Execution periods refer to a period of simulation time. STOMP-W allows the user to specify a single or multiple execution periods. For each execution period, the user can control the initial time step, maximum time step, time step acceleration factor, maximum number of Newton-Raphson iterations, and convergence criterion independently.

Initial time

If no initial time record is read for a restart simulation, the initial time record is obtained from the restart file.

Execution Time Step Controls

Two additional solution controls can be specified for each Execution Period input line: 1) the minimum time step, and 2) the time-step cut factor.  These optional solution controls must be specified together.  The minimum-time-step parameter sets the minimum time step for an execution period.  Without this control, STOMP-W quits after four time-step reductions.  Cyclic injection well schedules can yield simulations that execute with large time steps during steady injection periods, but require small time steps during the injection startup.  The minimum-time-step parameter allows the code to cut the time step to the minimum value before quitting.  The time-step cut factor is set to 0.2 by default, which means that time steps are cut to 20% of their value when a convergence failure occurs. Execution performance can be improved for some simulations by altering this factor.

Execution Time Parameters

Recommended values for the Time Step Acceleration Factor, Maximum Number of Newton-Raphson Iterations, and Convergence Criterion are 1.25, 8, and 1.e-06, respectively. Except under special circumstances, it is not recommended to change the value for the Convergence Criterion from its recommended value. This value has proven through numerous applications to achieve a good balance between accuracy and execution speed.  

Zero Time Step Simuations

Interfacial Averaging Variables and Schemes

While STOMP allows the user to specify alternative interfacial averaging schemes, it is strongly suggested that novice users in particular use the default schemes, as not all schemes are appropriate for all field variables.

Field variables, which include physical, thermodynamic, and hydrologic properties, are defined in the finite-difference formulation at the node centers.  Conversely, flux variables are defined at node interfaces.  Computation of flux variables requires knowledge of field variables at node interfaces.  Values of flux variables at node interfaces are evaluated by averaging the field values for the two nodes adjoining an interfacial surface.  Interfacial averaging schemes may be declared individually for each field variable through the Interfacial Averaging Variables input.

The default interfacial averaging schemes for the simulator are shown in the Table below.  For simulations of physical systems involving heat transfer, it should be noted that convergence problems might arise if the density properties are not averaged with upwind weighting.  Likewise, infiltration problems typically demonstrate strong dependencies on the relative permeability of the infiltrating fluid.