Physica A 387 (2008) 4541–4546 Contents lists available at ScienceDirect Physica A journal homepage: www.elsevier.com/locate/physa Permeability variation with fracture dissolution: Role of diffusion vs. drift Supti Sadhukhan a , Dibendyu Mal a , Tapati Dutta b , S. Tarafdar a,∗ a Condensed Matter Physics Research Centre, Physics Department, Jadavpur University, Kolkata 700032, India b Physics Department, St. Xavier’s College, Kolkata 700016, India article info Article history: Received 23 November 2007 Received in revised form 6 March 2008 Available online 28 March 2008 PACS: 47.60.+i 47.56.+r 05.40.Fb 47.11.-j Keywords: Permeability Porous media Random walk Peclet number abstract Pores and fractures in rocks are continually being reshaped through different chemical and physical processes. Fluids filling the pore space carry the different chemical species responsible for these changes. In the present work we study the relative effects of drift and diffusion of these particles, through a random walk. A bias imposed on the walker determines the competition between drift and diffusion, i.e. to a variation of the Peclet number. We find that the pore structure and hence permeability depends strongly on the bias. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Flow of reactive fluids in the pore space of rocks can cause dissolution of the surface and hence induce changes in rock structure and transport properties. Coupling between fluid flow and chemical kinetics plays an important role in geophysical problems such as the development of limestone caverns or the sequestration of CO 2 . Where local reaction kinetics is fast relative to reactant transport (i.e. the Damkohler number Da ≫ 1), fracture dissolution is strongly influenced by the Peclet number Pe. Pe weighs the relative magnitude of advective and diffusive transport of reactants. The process of channel formation is a contributing factor to ‘diagenesis’ in sedimentary rocks. The growth of worm-hole like channels through dissolution can be effectively studied through experiments [1] and simulations [2] in quasi-two dimensional systems. Experiments [1] show that the Peclet number for the flow, plays an important role in determining modification of the pore geometry. In the present work we report a computer simulation study in two-dimensions to simulate flow of a single fluid, through a random porous matrix for different values of the Peclet number (Pe). Our methodology is as follows (i) first we simulate fluid flow through a channel with some irregular shape and find out the permeability from Darcy’s law. For this step we employ a numerical finite difference solution of the steady state Navier–Stokes equation. The ratio of fluid flux to the applied constant pressure gradient, gives the initial permeability. (ii) In the next step we wish to simulate channel reshaping during flow, when the fluid erodes the walls, this is to be done for varying Peclet number. We take a simpler route for this process by simulating the fluid transport here through ∗ Corresponding author. Tel.: +91 3324 237540. E-mail address: sujata_tarafdar@hotmail.com (S. Tarafdar). 0378-4371/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.physa.2008.03.026