The Numerical Controls pane is on the SUTRA Options dialog box.
Fractional upstream weight (UP): Up is used to help stabilize oscillations due to highly advective transport or unsaturated flow. The recommended value is 0 (no upstream weighting). Upstream weighting increases the local effective longitudinal dispersivity of the simulation.
Pressure boundary condition factor (GNUP): "Pressure boundary condition factor or “conductance”. A high value causes SUTRA simulated and specified pressure values at specified pressure nodes to be equal in all significant figures. A low value causes simulated pressure to deviate significantly from specified values. The ideal value of GNUP causes simulated and specified pressures to match in the largest six or seven significant figures only, and deviate in the rest. Trial and error is required to determine an ideal GNUP value for a given simulation by comparing values specified with those calculated at the appropriate nodes for different values of GNUP. An initial guess of 0.01 is suggested." (Voss and Provost, 2010)
Concentration/temperature boundary condition factor (GNUU): "Concentration/temperature boundary condition factor. A high value causes SUTRA simulated values and specified values at specified concentration/temperature nodes to be equal in all significant figures. A low value causes simulated values to deviate significantly from specified values. The ideal value of GNUU causes simulated and specified concentrations or temperatures to match in the largest six or seven significant figures only, and deviate in the rest. Trial and error is required to determine an ideal GNUU value for a given simulation by comparing specified values with those calculated at the appropriate nodes for different values of GNUU. An initial guess of 0.01 is suggested." (Voss and Provost, 2010)
Maximum number of iterations allowed per time step to resolve nonlinearities (ITRMAX): "Maximum number of iterations allowed per time step to resolve nonlinearities. Set to a value of +1 for noniterative solution. Noniterative solution may be used for saturated aquifers when density variability of the fluid is small or for unsaturated aquifers when time steps are chosen to be small." (Voss and Provost, 2010)
Absolute iteration convergence criterion for pressure solution (RPMAX): When the maximum change in pressure during an iterative solution is less than RPMAX, the pressure solution has converged.
Absolute iteration convergence criterion for transport solution (RUMAX): When the maximum change in temperature or concentration during an iterative solution is less than RUMAX, the transport solution has converged.
