Application of the Parswms Parallelized Code for Simulation of Three-Dimensional Water Flow and Solute Transport in Containerized Soilless Substrates.

Simulation of three-dimensional water flow and solute transport in containerized variably saturated soilless substrates with complex hydraulic properties and boundary conditions necessitates high-resolution discretization of the spatial domain, which commonly leads to several million nodes requiring numerical evaluation. Even today’s computational power of workstations is not adequate to tackle such problems within a reasonable timeframe. Hence, parallization of the numerical code and utilization of supercomputers are required. We modified and applied the PARSWMS parallelized code that was developed for Linux and is amenable for solving the 3D Richard’s equation for water flow and the convection-dispersion equation for solute transport considering linear solute sorption. The code was modified to allow for nonlinear solute sorption behavior, and applied to simulate water flow and nitrogen and phosphorus transport and transformations in containerized soilless substrates such as perlite, volcanic tuff, coconut coir, Growstones, and mixtures thereof with the University of Arizona El Gato high performance computer cluster. Application of simulation results for economically efficient growth module design and irrigation management, as well as for optimization of substrates via mixing of organic and inorganic constituents will be discussed. In addition, simulations will be compared with results of a well-controlled greenhouse experiment.