Numerical analysis of spatial moments for reactive transport through fractured porous media

Abstract

We investigate the transport of chemicals in a fractured porous medium affected by multiprocess non-equilibrium. Advection-dispersion-reaction equation, which accounts for both the physical and chemical non-equilibrium, is used to simulate the transport in both the fracture and the porous medium, with linear equilibrium sorption and first-order degradation in the fracture, and physical and chemical non-equilibrium in the porous medium. Effect of first-order mass transfer, equilibrium sorption, first-order reverse sorption, porosity, groundwater velocity, fracture aperture and spacing on the transport process is examined. It was observed that increase in the value of mass transfer coefficient, reverse sorption coefficient, equilibrium sorption, decay rate coefficient, fracture retardation factor and porosity reduces the mean displacement and spreading of reactive solute in both the fracture and the porous block. As expected, higher value of groundwater velocity, fracture aperture and spacing increases the mean displacement and spreading of solute in both fracture and porous block. It is also seen that behaviour of mean displacement and variance are non-linear during small travel time and become linear at large travel time for reactive solute in the fracture and in the porous block. This numerical model can be used for remediation of fractured rock areas subjected to hazardous waste disposal.

Keywords:

• fractured porous media
• reactive chemicals
• spatial moments