How do physical properties vary spatially in a SUTRA model?
There are three ways in which physical properties can vary spatially in SUTRA: nodewise (a value is assigned to each node); elementwise (a value is assigned to each element); and as a function of pressure, concentration, or temperature. Porosity varies nodewise. Permeabilities and dispersivities vary elementwise. Unsaturated flow properties vary both nodewise and elementwise insofar as a “region number” is assigned to each node and element; the dependence of the unsaturated flow properties on pressure and region number is programmed by the user in subroutine UNSAT. (See “Q: How can I specify the unsaturated flow properties of my system?” below.) Fluid density varies linearly with solute concentration or temperature. For energy transport, fluid viscosity is a function of temperature; for solute transport viscosity is constant and uniform. All remaining physical properties are assigned a single, constant value throughout the model.
