Simulating The Effect Of Matrix Diffusion In Fractured Porous Media With Dual Domain Mass Transfer: A Modeling Comparison
Weingarten, Matthew 1 ; Hsieh, Paul 2
1 University of Colorado at ºù«ÍÞÊÓƵ, ºù«ÍÞÊÓƵ, CO, USA
2 U.S. Geological Survey, Menlo Park, CA, USA
Solute transport through fractured porous rocks can be described by advective-dispersive transport through the fractures and diffusive transport through the unfractured matrix. The effect of matrix diffusion is to reduce the effective solute velocity in the fracture until the matrix storage capacity has been reached. A model comparison between (1) fully simulating advection-dispersion in fractures and diffusive transport in the matrix and (2) the dual-domain mass transfer (DDMT) approach is presented. Numerous case studies of contaminant transport in highly fractured or heterogeneous media have shown that the DDMT model may improve model calibration at the field scale. The simulations are compared for a simple case involving solute transport through a single fracture and the matrix diffusion associated with this transport. Solute injection to the domain is varied to study the model responses to continuous injection and pulse injection under a variety of matrix porosities and dispersivities. This study finds the best-fit mass transfer rate coefficients under these various aquifer conditions at the very near field scale.
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