Three-dimensional convection and unstable displacement of viscous fluids from strongly encumbered space

Purpose of the present paper is to investigate 3D instability effects in convective flows of viscous fluid displaced by a less viscous one from strongly encumbered space, and to determine characteristics of displacement quality. Fluids are assumed incompressible and miscible. Extensive direct numerical simulations are used to study the sensitivity of the displacement process to variation of values of the main governing parameters. Comparison with results of two-dimensional simulations enabled us to investigate the effect of aspect ratio on instability growth in viscous fluids displacement. A 1D model with two fitting parameters is created in order to simulate behavior of the cross section averaged parameters of the flow.