A numerical model is developed for describing the transport of virus in a fracture-matrix coupled system with fracture-skin. An advective dispersive virus transport equation, including first-order sorption and inactivation constant is used for simulating the movement of viruses. Implicit finite-difference numerical technique is used to solve the coupled non-linear governing equations for the triple continuum model consisting of fracture, fracture-skin and the rock-matrix. A varying grid is adopted at the fracture and fracture-skin interface to capture the mass transfer. Sensitivity analysis was performed to investigate the effect of various properties of the fracture-skin as well as viruses on the virus concentration in the fractured formation with fracture-skin. Simulation results suggest that the virus concentration in the fracture decreases with increment in the fracture-skin porosity, fracture-skin diffusion coefficient, mass transfer coefficient, inactivation constant and sorption distribution coefficient, and with reduction in the fracture aperture. © 2012, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

Govindarajan Suresh Kumar

Department of Ocean Engineering

N.Natarajan

Finite difference method

Fracture

FRACTURE APERTURE

MASS TRANSFER

numerical model

porous medium

Sensitivity analysis

Transport process

Virus

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Geoscience Frontiers

Monitoring of BTX natural attenuation in a fractured rock aquifer is highly challenging due to lack of knowledge about the influence of interaction of heterogeneous domains on transport processes. Contaminant transport in a fractured rock is commonly investigated using dual continuum models by considering fracture and its surrounding rock–matrix as two different continuums. In this study, a numerical multi-component transport model based on a triple continuum modeling approach is developed to investigate the transport of dissolved BTX in a discretely fractured aquifer with fracture–skin. A residual BTX source zone is considered to be present at the fracture inlet. A multi-component dissolution model is coupled with the present numerical model to simulate the dissolution of benzene, toluene and xylene at the residual BTX source. Dissolved BTX components are considered to undergo sorption and biodegradation in addition to advection and dispersion within the fracture. Dissolved BTX components diffusing to fracture–skin and rock–matrix are considered to undergo sorption and biodegradation in fracture–skin and rock–matrix. A novel sensitivity analysis approach based on spatial moments is introduced in the manuscript to investigate the sensitivity of various flow and transport parameters of fracture–skin and rock–matrix on dissolved BTX mass retained in fracture and matrix. The presence of fracture–skin is found to significantly affect the concentration distribution and mass retention of dissolved BTX components in a fractured aquifer. © 2017, Springer-Verlag GmbH Germany.

Environmental Earth Sciences

Multi-component transport of BTX in a discretely fractured aquifer with fracture–skin: numerical investigation and sensitivity analysis

Fractures act as a highly permeable conduit for flow in naturally fractured reservoir. Geo-chemical reactions inside fractures may lead to partial or complete filling of pore spaces inside fractures over time. This reduction in fracture aperture directly affects its capability to transport fluid. The current study presents a 1-D mathematical model to simulate the geochemical filling of natural fractures. The fracture walls have been represented by simple mathematical functions to reflect variable aperture of natural fractures. Mass transfer through convection/diffusion and mineral precipitation due to precipitation/dissolution reaction were solved as a simplified mathematical representation of the actual processes. Precipitation reaction is coupled with mass transport by the fluid to ensure mass conservation of reacting components. For simplification, calcite precipitation in fracture has been modelled. The effect of pressure drop, diffusion constant, type of fracture aperture profile on evolution of fracture aperture was simulated in this study. Comparison is made between increasing, decreasing and constant fracture profiles to understand their effect on fracture evolution. This study aims to present a methodology to model variable fractures and study its effect on deposition inside the fracture. The model shows that the simple parallel model over predicts the precipitation that occurs in a fracture. © 2016 Indian Society for Hydraulics.

ISH Journal of Hydraulic Engineering

Modelling of mineral precipitation in fractures with variable aperture

The contaminant transport mechanism in fractured clay porous media has been analysed using numerical modelling. Implicit finite difference has been used to develop the numerical model. A constant continuous source of contaminants has been assumed at the inlet of the fracture. The domain is considered to be saturated. A varying grid is considered in the fracture skin to account for the flux transfer at the interface of the fracture and the skin. The effect of constant dispersion as well as distance-dependent dispersion on the contaminant transport mechanism has been analysed in the presence of fracture skin. The contaminants are assumed to follow Freundlich non-linear sorption isotherm. Sensitivity analysis has been conducted to study the effect of different fracture-skin porosities, skin diffusion coefficients, half fracture apertures, fluid velocities and skin thicknesses on the solute transport mechanism within the fractured clay porous media. Results suggest that amount of solute diffusion into the clay matrix is directly proportional to the fracture-skin porosity and fracture-skin diffusion coefficient and inversely proportional to thickness of the half fracture aperture and the fluid velocity. The role of non-linear sorption is insignificant and scale-dependent dispersivity results in enhanced mass diffusion from the fracture. © 2014 Indian Society for Hydraulics.

Effect of fracture-skin formation in clay fractured porous media

Fractures act as a highly permeable conduit for flow in naturally fractured reservoir. Geo-chemical reactions inside fractures may lead to partial or complete filling of pore spaces inside fractures over time. This reduction in fracture aperture directly affects its capability to transport fluid. The current study presents a 1-D mathematical model to simulate the geochemical filling of natural fractures. The fracture walls have been represented by simple mathematical functions to reflect variable aperture of natural fractures. Mass transfer through convection/diffusion and mineral precipitation due to precipitation/dissolution reaction were solved as a simplified mathematical representation of the actual processes. Precipitation reaction is coupled with mass transport by the fluid to ensure mass conservation of reacting components. For simplification, calcite precipitation in fracture has been modelled. The effect of pressure drop, diffusion constant, type of fracture aperture profile on evolution of fracture aperture was simulated in this study. Comparison is made between increasing, decreasing and constant fracture profiles to understand their effect on fracture evolution. This study aims to present a methodology to model variable fractures and study its effect on deposition inside the fracture. The model shows that the simple parallel model over predicts the precipitation that occurs in a fracture.

Journal of Environmental Engineering

Breakthrough Curves and Simulation of Virus Transport through Fractured Porous Media

Journal of Hydro-environment Research

Numerical analysis of virus transport through heterogeneous porous media

Colloids and Surfaces A: Physicochemical and Engineering Aspects

Numerical modelling of colloid transport in sets of parallel fractures with fracture skin

Environmental Science & Technology

Removal of Biocolloids Suspended in Reclaimed Wastewater by Injection into a Fractured Aquifer Model

Transport in Porous Media

Transport of Viruses Through Saturated and Unsaturated Columns Packed with Sand

Effect of fracture-skin on virus transport in fractured porous media