Escoamento viscoso em fraturas auto-afins

• Autor(a) principal: Leandro Filho, Francisco de Assis
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/40261
• topic: Escoamento; Fluidos; OpenFOAM

This work aims to study the process of flow of a fluid through uneven surfaces. Initially will address the dynamics of flow through rough surfaces with self-affine geometry. Essentially, the relevant aspects in understanding the flow of irregular structural systems are closely associated with topological and morphological formation of the half. The topology and morphology of the irregular system will be described. It will be appreciated that the geometry of the interfaces that constitute the rough channel feature invariant under transformations statistical properties of anisotropic scale, i.e., can be characterized as self-affine fractal surfaces. The irregular nature of this geometry adds a degree of complexity to the flow problem, reflecting on the properties of velocity and pressure fields. This study aims to investigate the fluid flow in self-affines surfaces through direct numerical simulations of the Navier-Stokes equations. We investigate the influence of the surface roughness to the viscous and non-viscous flow of Newtonian fluids in self-affine joints and fractured surfaces. We denote that the effective permeability of the decays exponentially with the Hurst exponent, used as a quantitative measure of the surface roughness. Nonlinear contributions to the fluid hydraulic resistance become important for sufficiently high Reynolds numbers, due inertial forces contributions, which is typical of experiments. To cubic order, we fi nd that it is possible to nd a universal behavior of the hydraulic resistance of the system, with the onset of the nonlinear corrections to Darcy's law being proportional to the Hurst exponent. This implies that the system can be described macroscopically only by the permeability even for very rough surfaces (H ~ 0.3). We also nd the spontaneous occurrence quasi-one-dimensional channeling in the flow, even with no relative shear displacement between the upper and lower surfaces of the self-a ne fracture joints. This unexpected behavior is quanti ed here using the participation index.