Center for Exposure Assessment Modeling (CEAM) (EPA)Center for Exposure Assessment Modeling (CEAM)
VADOFT is a finite-element code that simulates one-dimensional, single-phase
moisture and solute transport in unconfined, variably saturated porous media.
Transport processes include hydrodynamic dispersion, advection, linear
equilibrium sorption, and first-order decay. VADOFT employs the Galerkin
finite-element technique to approximate the governing equations for flow and
transport and allows for a wide range of nonlinear flow conditions. Boundary
conditions of the variably saturated flow problems may be specified in terms
of prescribed pressure head or prescribed volumetric water flux per unit
area. Boundary conditions of the solute transport problem may be specified
in terms of prescribed concentrations of prescribed solute mass flux per unit
area. All boundary conditions may be time dependent. An important feature
of the algorithm is the use of constitutive relationships for soil water
characteristic curves based on soil texture.
Hysteresis effects in the constitutive relationships are assumed to be negligible. Sorption and decay of the solute are described by a linear equilibrium isotherm and a lumped first-order decay constant. The code considers only single porosity soil media and does not simulate flow or transport in fractured porous media or structured soils.
Three sets of benchmark problems were used to test the VADOFT code; numerical results from VADOFT were compared with analytical solutions and results using two other finite-element codes (MULLINS et al. 1993).
Source of the Abstract:
Mullins, J.A., R.F. Carsel, J.E. Scarbrough, A.M. Ivery. 1993