Sharif Digital Repository

The solution to the hyperbolic conservation laws may involve discontinuities or shocks even if initial condition is smooth. Devising low cost methods which can identify shocks accurately, has always been a challenge. This project focuses on applying high resolution schemes to the solution of two and three phase Buckley-Leverett equation and hyperbolic conservation laws in general.Buckley-Leverett equation is a transport equation which is used to describe two and three phase flows in porous media. Weighted Essentially Non-Oscillatory (WENO) schemes with reconstruction on fluxes in finite difference formulation are used to solve one dimensional systems of equations including Euler equation as... 

In this study, a new finite-element-volume (FEV) arbitrary Lagrangian-Eulerian (ALE) method is suitably extended to simulate the three-phases flows air, liquid water droplets and ice in ice accretion, i.e., over flying object surfaces. This methods benefit from the advantages of both finite-volume and finite-element methods. This method is developed for the first time to simulate three phases turbulent flows. Since the ice formation and growth needs grid movement consistant with ice boundary movement, we have used ALE approach to fulfill this requirment. In this regard, we use the linear spring analogy approach to move the hybrid triangular-rectangular mesh suitably. Facing with a chaotic... 

Today, the Oil industry, much progress has been made in terms of increasing the productivity of reservoirs. In this method, generally one or more fluids are injected into wells to help, extract more oil from the reservoir. Knowledge of the main parameters in this flow of two or three phase fluid in the reservoir is most important. If fractured reservoirs are studied, the multiphase flow are much more complex and require more information about that. Unfortunately, due to the complexity of fractured reservoirs and fluid flow within them, little research has been done on them. The studies about two or three phase flow in fractured reservoirs are classified in two groups, modeling and laboratory... 

In this work a generalized non-equilibrium model of three-phase flow in porous media including gravity as well as capillary terms is developed and used for analysis of Riemann’s problem in several three-phase systems. The proposed model uses the extension of Barenblatt model to three-phase systems considering dynamic effects in both relative permeability and capillary pressure functions. We compare the solution of the Riemann’s problem when non-equilibrium effects are included. While equilibrium formulation develops unstable oscillatory solution in the elliptic region, non-equilibrium solution is smooth and stable. The proposed non-equilibrium model is validated by the experimental data of... 

When producing oil reservoirs, if the reservoir formation has a low resistance, the entry of sand into the oil wells is definite. Creating a bed of sand particles at the bottom of the tube can cause operational problems such as reduced production and excessive drop in pressure, equipment failure, erosion and corrosion. By keeping the velocity above the sedimentation rate (the speed of solid particles always moving and above the bottom of the tube), preventing these problems can be prevented. A wide analysis of the flow regime in the horizontal and sloping pipelines for the flow of water, oil, and sand has been made in this context. Also, the effect of sand concentration on the flow regime... 

Gas–liquid–solid fluidized beds are widely used in the petrochemical, biochemical, biotechnology, and wastewater treatment industries. These beds have the advantage of appropriate mass and heat transfer, better temperature control, and more solid content. In the present work, computational studies have been conducted on two-dimensional tapered fluidized beds to characterize their hydrodynamic behaviour. The presence of two dispersed phases in these beds results in difference in interphase interactions compared to two-phase fluidized beds. Generally, the three phase fluidized beds create a more complex flow pattern than the conventional type of fluidized beds. Three-phase flow in these beds...