Finally, interfacial behaviors of multi-layer liquid-liquid flow of non-Newtonian and Newtonian fluids in an inclined channel are investigated. The lighter fluid is replaced by a shear thinning, non-Newtonian fluid. A proper empirical model for viscosity constitutive equation is employed for describing the non-Newtonian behavior of the fluid to allow for numerical computation. A comparative study is conducted with suitable range of flow parameters using non-Newtonian fluid as the lighter fluid occupying the upper layer of channel. The thickness of the PEG layer increases as the degree of shear thinning increases. This effect is observed only with gravity induced wavy interface. Shear induced wavy interface does not manifest any effect of shear thinning of the oil for the range of degree of shear thinning effects considered in this study.
Immiscible multi-fluid flows are of great industrial importance. The nature of such flows and their stability is the topic of study here. Results of the present study has are prescribed in two parts. First part discusses the two layer fluid flows in pipe geometry while the second part looks in the properties of two layer fluid flows in inclined channel geometry.
Microfluidic devices are utilized in a wide range of applications, including micro-electromechanical devices, drug delivery, biological diagnostics and micro-fuel cell systems. Of particular interest here are liquid-liquid microfluidic systems; which are used in drug discovery, food and oil industry amongst others. Increased understanding of the fundamentals of flows in such devices and an improved capacity to design them can come from modelling. In the case of liquid-liquid flows in microfluidic systems, it is necessary to explicitly model the behaviour of the individual liquid phases. Such explicit numerical simulation (ENS) as it is termed requires advanced numerical methods that are able to evaluate flow involving multiple deforming fluid domains within often complex boundaries. Smoothed Particle Hydrodynamics (SPH), a Lagrangian meshless method, is particularly suitable for such problems. This use of a CFD allows determination of parameters that are difficult to determine experimentally because of the challenges faced in microfabrication. The study reported in this thesis addresses these concerns through development of a new SPH-based model to correctly capture the immiscible liquid-liquid interfaces in general and for a microfluidic hydrodynamic focusing system in particular. The model includes surface tension to enforce immiscibility between different liquids based on a new immiscibility model, enforces strict incompressibility, and allows for arbitrary fluid constitutive models. This work presents a detailed study on the effects of various flow parameters including flowrate ratio, viscosity ratio and capillary number of each liquid phase, and geometry characteristics such as channel size, width ratio, and the angle between the inlet main and side channels on the flow dynamics and topological changes of the multiphase microfluidic system. According to our findings, both flowrate quantity and flowrate ratio affect the droplet length in the dripping regime and a large viscosity ratio imposes an increase in the flowrate of the continuous phase with the same capillary number of the dispersed phase to attain dripping regime in the outlet channel. Also, increasing the side channel width causes longer droplets, and the right-angled design makes the most efficient focusing behaviour. This study will provide great insights in designing microfluidic devices involving immiscible liquid-liquid flows.
Numerical simulation of multiphase reactors with continuous liquid phase provides current research and findings in multiphase problems, which will assist researchers and engineers to advance this field. This is an ideal reference book for readers who are interested in design and scale-up of multiphase reactors and crystallizers, and using mathematical model and numerical simulation as tools. Yang and Mao's book focuses on modeling and numerical applications directly in the chemical, petrochemical, and hydrometallurgical industries, rather than theories of multiphase flow. The content will help you to solve reacting flow problems and/or system design/optimization problems. The fundamentals and principles of flow and mass transfer in multiphase reactors with continuous liquid phase are covered, which will aid the reader's understanding of multiphase reaction engineering. Provides practical applications for using multiphase stirred tanks, reactors, and microreactors, with detailed explanation of investigation methods. Presents the most recent research efforts in this highly active field on multiphase reactors and crystallizers. Covers mathematical models, numerical methods and experimental techniques for multiphase flow and mass transfer in reactors and crystallizers.
Numerical simulation of multiphase reactors with continuous liquid phase provides current research and findings in multiphase problems, which will assist researchers and engineers to advance this field. This is an ideal reference book for readers who are interested in design and scale-up of multiphase reactors and crystallizers, and using mathematical model and numerical simulation as tools. Yang and Mao's book focuses on modeling and numerical applications directly in the chemical, petrochemical, and hydrometallurgical industries, rather than theories of multiphase flow. The content will help you to solve reacting flow problems and/or system design/optimization problems. The fundamentals and principles of flow and mass transfer in multiphase reactors with continuous liquid phase are covered, which will aid the reader's understanding of multiphase reaction engineering. - Provides practical applications for using multiphase stirred tanks, reactors, and microreactors, with detailed explanation of investigation methods - Presents the most recent research efforts in this highly active field on multiphase reactors and crystallizers - Covers mathematical models, numerical methods and experimental techniques for multiphase flow and mass transfer in reactors and crystallizers
Compared to the traditional modeling of computational fluid dynamics, direct numerical simulation (DNS) and large-eddy simulation (LES) provide a very detailed solution of the flow field by offering enhanced capability in predicting the unsteady features of the flow field. In many cases, DNS can obtain results that are impossible using any other me
