Abstract: Two-phase and multi-phase flows are common flow types in fluid mechanics engineering. Among the basic and applied problems of these flow types, two-phase parallel flow is the one that two immiscible fluids flow in the vicinity of each other. In this type of flow, fluid properties (e.g. density, viscosity, and temperature) are different at the two sides of the interface of the two fluids. The most challenging part of the numerical simulation of two-phase flow is to determine the location of interface accurately. In the present work, a coupled interface tracking algorithm is developed based on Arbitrary Lagrangian-Eulerian (ALE) approach using a cell-centered, pressure-based, coupled solver. To validate this algorithm, an analytical solution for fully developed two-phase flow in presence of gravity is derived, and then, the results of the numerical simulation of this flow are compared with analytical solution at various flow conditions. The results of the simulations show good accuracy of the algorithm despite using a nearly coarse and uniform grid. Temporal variations of interface profile toward the steady-state solution show that a greater difference between fluids properties (especially dynamic viscosity) will result in larger traveling waves. Gravity effect studies also show that favorable gravity will result in a reduction of heavier fluid thickness and adverse gravity leads to increasing it with respect to the zero gravity condition. However, the magnitude of variation in favorable gravity is much more than adverse gravity.
Abstract: The damage caused by surge waves generated in water
bodies by flow-like landslides can be very high in terms of human
lives and economic losses. The complicated phenomena occurred in
this highly unsteady process are difficult to model because three
interacting phases: air, water and sediment are involved. The problem
therefore is challenging since the effects of non-Newtonian fluid
describing the rheology of the flow-like landslides, multi-phase flow
and free surface have to be included in the simulation. In this work, the
commercial computational fluid dynamics (CFD) package FLUENT is
used to model the surge waves due to flow-like landslides. The
comparison between the numerical results and experimental data
reported in the literature confirms the accuracy of the method.