Soft Matter and Complex Systems Seminar
sala 2.08, ul. Pasteura 5
2016-11-04 (09:30) 
Anthony Ladd (Unversity of Florida)
Numerical simulations of fracture dissolution
Fractures take up only about 1% of the subsurface pore space, but in soluble rocks they make the most important contribution to groundwater transport; for example in the development of karst formations. The increase in permeability due to dissolution of the fracture surfaces gives rise to a number of questions that are important for waste storage systems, sequestration, oil and gas recovery, and dam stability.
In this talk I will review numerical simulations of fracture dissolution using 1D, 2D, and 3D models for the fracture geometry. Historically, lower dimensional models have added considerable insight to our understanding of the dynamics of a dissolving fracture. I will outline the important contributions from these models and their limitations in comparison with recent fully three-dimensional simulations. While it has been known for some time that one-dimensional models omit crucial aspects of the dissolution dynamics, recently we have shown that two dimensional models do not correctly describe the flow in tube-like conduits which develop as the fracture dissolves.
Three-dimensional simulations have shown that the elliptical conduits characteristic of karst formations evolve very early in the dissolution, even prior to breakthrough. They can be nucleated from local enhancements of aperture, from spatially random aperture distributions, or even from variations in the central plane of an otherwise smooth fracture. The shape of the conduit depends on flow rate: at small flow rates they are circular, but expand horizontally into elliptical shapes as the flow rate increases.
In this talk I will review numerical simulations of fracture dissolution using 1D, 2D, and 3D models for the fracture geometry. Historically, lower dimensional models have added considerable insight to our understanding of the dynamics of a dissolving fracture. I will outline the important contributions from these models and their limitations in comparison with recent fully three-dimensional simulations. While it has been known for some time that one-dimensional models omit crucial aspects of the dissolution dynamics, recently we have shown that two dimensional models do not correctly describe the flow in tube-like conduits which develop as the fracture dissolves.
Three-dimensional simulations have shown that the elliptical conduits characteristic of karst formations evolve very early in the dissolution, even prior to breakthrough. They can be nucleated from local enhancements of aperture, from spatially random aperture distributions, or even from variations in the central plane of an otherwise smooth fracture. The shape of the conduit depends on flow rate: at small flow rates they are circular, but expand horizontally into elliptical shapes as the flow rate increases.