Simulation, analysis and computational characterization of fingering patterns in fluids displacement on porous media. / Simulação, análise e caracterização computacional de padrões de fingering em deslocamentos de fluidos em meios porosos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

In this work, the patterns related to the displacement process of an interface between two ftuids of different mobilities are studied computationally. In the literature, the formation process of these patterns is known as fingering, a type of dynamic instability in the interface between two miscible fluids, where the fingers are classified in two types: density fingering and viscous fingering. Those instabilities can be analyzed using 1D concentration profiles from the average concentration on the concentration matrix in transverse and longitudinal directions of interface propagation. In the first part of this work, the main goal is to study comparatively these two types of fingering from its 1D averaged concentration profiles. To do this, it is used beyond usual structural measures as the mixing length and mean wave number, the gradient asymmetry coefficient as a measure of bilateral asymmetries typically found in the averaged concentration profiles. The results show consistency with the classical analysis of fingering patterns and highlight the similarities and differences between the two types of instabilities indicating the moment that it occur in the nonlinear regime. This analysis is applied to DF patterns, in innovative way, varying the gravity acceleration in this model. For this analysis, the results indicate that the fingering formation results in differents patterns for dífferent values of gravitational acceleration. In the second part of work, it is analyzed a system which presents the fingering phenomenon according to degree of structural complexity. The interaction between the dynamics of coalescence, characteristic of the Rayleigh-Taylor instability, and the number of wavelength, characteristic of diffusive instability, may lead to development of space-time patterns structurally complex. In a general way, all results based on spectral measures, identify the transitions to the strongly nonlinear regime where the diffusive instability appears as the main responsible for the spatio-temporal chaos identified in tho analysis. As a fundamental goal, this study contributes to new simulations and structural measures of fingering patterns in porous media, providing a new characterization of nonlinear processes involved, where the structural complexity shows direct dependence on the choice of constitutive physical parameters.

ASSUNTO(S)

instabilidade de rayleigh-taylor gradient pattern analysis sauffman-taylor instability análise de padrôes gradientes computational characterization instabilidade de sauffman-taylor hydrodinamic instabilities raileigh-taylor instability instabilidade caracterização computacional

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