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No presente estudo é analisado numericamente, com auxílio do software Ansys Fluent, a mobilização de óleo mediante injeção de água em uma geometria bidimensional formado por placas paralelas com uma microcavidade quadrada que, de forma simplificada, representa as gargantas e poros da rocha-reservatório portadora de óleo. O objetivo fundamental é avaliar a influência da curvatura da quina no processo de mobilização do óleo. Para isso, o efeito de três raios de curvatura são comparados com a quina formada por um ponto. O problema é transiente, bifásico, com forças capilares dominantes sobre as viscosas e as de inercia. Os resultados obtidos, para o caso com quina aguda, é coincidente com o trabalho de Coelho, Pena e Romero (2016). A análise dos casos considerados permitem destacar que ao final do processo de deslocamento uma fração de óleo continuará trapeado na microcavidade. Também, para a geometria considerada e independente do raio de curvatura da quina, existem três regiões distintas ao se avaliar a fração volumétrica média de óleo. A primeira região em que a redução de óleo é acentuada. Uma segunda região onde a retirada de óleo torna-se cada vez mais lenta. E uma terceira que identifica a saturação de óleo residual. Finalmente, o processo se torna mais eficiente quanto maior for o raio de curvatura da quina do microporo. Esta relação, pelo menos para os casos analisados, é linear.

In this work, the oil displacement process due to water injection in a two-dimensional geometry formed by parallel plates with a micro square cavity that, in simplified form, represents the pores of the oil reservoir rock is analyzed numerically. This was achieved with the Ansys Fluent software that uses the finite volume method. The main aim of this paper is the investigation of the influence of a rounded corner of the geometry in the oil displacement process. In the multiphasic, transient, Newtonian flow, capillary forces prevailing over the inertial and viscous forces. The results obtained, for the case with square corners, coincide with the work of Coelho, Pena e Romero (2016). The analysis shows that, for the four cases considered, at the end of the oil displacement process a portion of the oil will remain trapped in the microcavity. Additionally, for the considered geometry, independent of the radius of curvature of the rounded corners, there are three distinct regions when evaluating the average oil volume fraction. A first region, where the reduction of oil is accentuated, then a second region, where the oil displacement becomes slower, and finally a third region, identified by the saturation of the residual oil. The process becomes more efficient as the radius of curvature of the micropore with rounded corners increases. This relation, at least for the cases analyzed, is linear. [ABSTRACT FROM AUTHOR]

The limitation of countercurrent flow, or flooding, is a phenomenon characterized by the control that a gas exerts in the flow of a liquid in the opposite direction. This effect has received special attention from the nuclear area due to its influence on the thermofluid dynamics behavior of Pressurized Water Reactor (PWR) during a Loss of Coolant Accident (LOCA). Numerical modeling is a fundamental tool for the development of nuclear engineering. This work has the purpose to demonstrate that the Computational Fluid Dynamics (CFD) software OpenFOAM® has the potential to be used in the modeling of the countercurrent flow phenomenon that occurs in the core of PWR reactors. An introduction of CFD using OpenFOAM. The solver used was interFoam, where it was observed that openFOAM presented satisfactory results for the multiphase flow study. [ABSTRACT FROM AUTHOR]