User:Mburton/HydroGeoSphere Simulation Control

Many of the inputs required for a HydroGeoSphere simulation are configured in the Simulation Control, which is accessed by right-clicking on the simulation in the Project Explorer. This includes, but is not limited to: time stepping, output, zones, and initial conditions. The following is a full list of parameters available in the Simulation Control dialog.

HydroGeoSphere Simulation Control dialog

General Tab

• Description: this purpose of this textbox is to enter a description that will appear at the top of the .grok file.
• Transient flow: this checkbox adds a time-stepping, transient flow solution.
• Unsaturated: this checkbox adds a variably-saturated flow solution.
• Finite difference
  • Finite difference mode: uses the finite difference approach rather than default finite element method.
  • Control volume: uses the control-volume finite difference approach instead of the default standard finite difference approach. This option results in a conservative scheme with better numerical stability than the default approach.
• Domains
  • Porous media: include the porous media domain. This option is always on.
  • Surface flow: includes the surface flow domain.
    • Dual nodes for surface flow: use the dual-node approach to define the discrete surface flow domain. This option is always on.
  • ET: includes the ET (evapotranspiration) domain.

Units Tab

• Units: a dropdown menu that converts the default values into the specified system. It does not convert properties specified in any .grok, .mprops, etc. files.
  • Kilogram-metre-second
  • Kilogram-metre-minute
  • Kilogram-metre-hour
  • Kilogram-metre-day
  • Kilogram-metre-year
  • Kilogram-centimetre-second
  • Kilogram-centimetre-minute
  • Kilogram-centimetre-hour
  • Kilogram-centimetre-day
  • Kilogram-centimetre-year
• Gravitational acceleration: set a default gravitational acceleration value.

Saturated Flow Tab

• No fluid mass balance: this checkbox suppresses the calculation of fluid mass balance information, which is, by default, computed at each time step.
• Flow solver maximum iterations: maximum number of flow solver iterations, defaults to 2000.
• Flow solver convergence criteria: flow solver convergence tolerance.
• Flow solver detail: controls the level of detail of the solver performance. This defaults to 0-no information, but can also be set to 1-full information.

Variably Saturated Flow Tab

• Upstream weighting factor: defaults to 1.0. This value should be in the range of 0.5 (central weighting) and 1.0 (upstream weighting).
• Newton iteration parameters
  • Remove negative coefficients: forces negative inter-nodal conductance to zero.
  • No nodal flow check: turns off nodal flow check, which is on by default.
  • Nodal flow check tolerance: defaults to 10^-2. This is used to set constraints to the nodal flow error.
  • Underrelaxation factor: factor for the Newton iteration. This defaults to one, but can range from zero to one.

Time Stepping Tab

• General timestep settings
  • Initial time: defaults to 0. This can be used to index the times from an earlier run if the simulation needs to be restarted.
  • Initial timestep: used to assign a new value for the initial timestep, which normally defaults to 0.01.
  • Maximum timestep: used to assign a new value as the maximum size for a timestep. The maximum timestep defaults to 10^25.
  • Minimum timestep: used to assign a new value as the minimum size for a timestep. This defaults to 10^-10. If the timestep size is smaller than the default, HydroGeoSphere will stop.
  • Time varying maximum timestep: this allows the creation of a table to create a dataset where the maximum timestep will vary depending on the time unit.
  • Target times: allows for the creation of a list of target times to add to a current list of target times.
  • Minimum timestep multiplier: used to assign a new value for the minimum timestep multiplier, which defaults to 0.5.
  • Maximum timestep multiplier: used to assign a new value for the maximum timestep multiplier, which defaults to 2.
  • Jacobian epsilon: the shift in the pressure head used to numerically compute the derivatives in the Jacobian matrix.
  • Minimum relaxation factor for convergence: defaults to 0.95. Convergence of the Newton iteration can only be achieved when the computed relaxation factor is larger than the minimum value.
  • Newton maximum iterations: defaults to 15. If this number is exceeded during a timestep, then the current timestep length is reduced by half and a new solution is attempted.
  • Newton minimum iterations: defaults to 0. Convergence of the Newton iteration can only be achieved only after it has performed the minimum number of iterations.
  • Newton absolute convergence criteria: defaults to 10^-5. Convergence of the Newton iteration in achieved when the maximum absolute nodal change in pressure head over the domain for one Newton iteration is less than this value.
  • Newton residual convergence criteria: defaults to 10^-8. Convergence of the Newton iteration is achieved when the maximum absolute nodal residual over the domain for one Newton iteration is less than this value.
  • Newton maximum update for head: defaults to 1.0. This value is used to calculate the underrelaxation factor in the equation.
  • Newton maximum update for depth: update equations are the same as those for "Newton maximum update for head", but are applied to water depth.
  • Newton absolute maximum residual: if after any iteration of the Euclidean norm of the Newton residual exceeds this, then the Newton iteration is restarted with a smaller timestep. by default this tolerance is set to zero, which is treated the same as infinity.
  • Newton maximum residual increase: defaults to 10^30. If after any iteration the Newton residual increases by a factor of more than this, then the Newton iteration is restarted with a smaller timestep.
• Adaptive timestep settings
  • Head control: maximum allowed change in nodal head during any timestep.
  • Water depth control: maximum allowed change in surface water depth during any timestep.
  • Saturation control: maximum allowed change in nodal saturation during any timestep.
  • Newton iteration control: maximum allowed change in Newton-Raphson iterations during any timestep.

Output Tab

• Output times: listed items are added to the current set of output times.

Zones Tab

• Read porous media zones from file: import a data set containing the element zone numbers for the porous media domain.
• Read surface flow zones from file: import a data set containing the element zone numbers for the surface flow domain.
• Read ET zones from file: import a data set containing the element zone numbers for the ET domain.

Initial Conditions Tab

• Head
  • Initial head
  • Initial head depth to water table
  • Initial head surface elevation
  • Initial head from file: import an initial head value set from a file.
• Water depth
  • Initial water depth
  • Initial water depth from file: import an initial water depth value set from a file.