Explicit Finite Difference Solution for One Dimensional Solute Transport of Unstable Flow

Abstract

The study on the transport law of soil solute is of great significance for soil salt and alkali, soil and fertilizer utilization, production of industrial and mineral industry and the discharge of pollutants caused by rainwater runoff and geological storage of nuclear waste [1-5]. The solute dissolved in the groundwater can not only move with the groundwater, but also diffuse as the diffusion movement of water molecules. Therefore, the soil solute transport model is composed of the problem of groundwater flow and the solute transport. Solution of solute transport requires simultaneous solution of water flow problem and solute transport problem. For problems like the safety assessment of geological storage of nuclear wastes, groundwater pollution and the design of remediation, it is necessary to predict the flow of groundwater and the transport of contaminated materials in large space and long time span. There are many methods for determining the solutions such as finite difference method, finite element method, boundary element method and finite analysis method. Among these numerical solutions, the finite difference method is the most widely used for its simplicity and clear physical meaning and so on. Compared with the extensive attention of the steady flow solute transport, the study on the solute transport of unsteady flow is almost blank in China[1,3]. In this paper, a numerical formula of the explicit time domain difference method for one dimensional solute transport is established for the first time. The temporal and spatial distribution of solute concentration is calculated and the results are qualitatively analyzed.