By default, HydroGeoSphere uses the upstream weighting scheme (weighted harmonic mean) for relative permeability, with an upstream weighting factor value of 1.0. The default behaviour can be changed using the following commands:

Upstream weighting factor

1. upwfactor Upstream weighting factor.

Assigns a new value for the upstream weighting factor, which defaults to 1.0. This value should be in the range from 0.5 (central weighting) to 1.0 (upstream weighting).

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Central weighting

Causes HydroGeoSphere to use central weighting (weighted arithmetic mean) instead of upstream weighting.

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Primary variable switching

Causes HydroGeoSphere to use the primary variable substitution technique outlined in Section 3.13.3.

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If desired, the default values of ${\displaystyle tol_{f}}$ and ${\displaystyle tol_{b}}$, the upper and lower limits for variable substitution (see Equation 3.99) can be changed using the following commands:

Upper limit

1. switch_t Upper limit of the variable substitution approach, tol_f in Equation 3.99. The default value is 0.99.

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Lower limit

1. switch_f Lower limit of the variable substitution approach, tol_b in Equation 3.99. The default value is 0.89.

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