Author: J. LaasonenPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Numerical Modelling of Jets and Plumes
Author: J. LaasonenTurbulent Jets and Plumes
Author: Joseph Hun-wei LeePublisher: Springer Science & Business Media
ISBN: 1461504074
Category : Science
Languages : en
Pages : 391
Book Description
Jets and plumes are shear flows produced by momentum and buoyancy forces. Examples include smokestack emissions, fires and volcano eruptions, deep sea vents, thermals, sewage discharges, thermal effluents from power stations, and ocean dumping of sludge. Knowledge of turbulent mixing by jets and plumes is important for environmental control, impact and risk assessment. Turbulent Jets and Plumes introduces the fundamental concepts and develops a Lagrangian approach to model these shear flows. This theme persists throughout the text, starting from simple cases and building towards the practically important case of a turbulent buoyant jet in a density-stratified crossflow. Basic ideas are illustrated by ample use of flow visualization using the laser-induced fluorescence technique. The text includes many illustrative worked examples, comparisons of model predictions with laboratory and field data, and classroom tested problems. An interactive PC-based virtual-reality modelling software (VISJET) is also provided. Engineering and science students, researchers and practitioners may use the book both as an introduction to the subject and as a reference in hydraulics and environmental fluid mechanics.
Recent Research Advances in the Fluid Mechanics of Turbulent Jets and Plumes
Author: P.A. DaviesPublisher: Springer Science & Business Media
ISBN: 9401109184
Category : Science
Languages : en
Pages : 513
Book Description
Challenging problems involvrllg jet and plume phenomena are common to many areas of fundamental and applied scientific research, and an understanding of plume and jet behaviour is essential in many geophysical and industrial contexts. For example, in the field of meteorology, where pollutant dispersal takes place by means of atmospheric jets and plumes formed either naturally under conditions of convectively-driven flow in the atmospheric boundary layer, or anthropogenically by the release of pollutants from tall chimneys. In other fields of geophysics, buoyant plumes and jets are known to play important roles in oceanic mixing processes, both at the relatively large scale (as in deep water formation by convective sinking) and at the relatively small scale (as with plume formation beneath ice leads, for example). In the industrial context, the performances of many engineering systems are determined primarily by the behaviour of buoyant plumes and jets. For example, (i) in sea outfalls, where either sewage or thermal effluents are discharged into marine and/or freshwater environments, (ii) in solar ponds, where buoyant jets are released under density interfaces, (iii) in buildings, where thermally-generated plumes affect the air quality and ventilation properties of architectural environments, (iv) in rotating machinery where fluid jet~ are used for cooling purposes, and (v) in long road and rail tunnels, where safety and ventilation prcedures rely upon an understanding of the behaviour of buoyant jets. In many other engineering and oceanographic contexts, the properties of jets and plumes are of great importance.
Turbulent Buoyant Jets and Plumes
Author: Wolfgang RodiPublisher: Elsevier
ISBN: 1483189872
Category : Technology & Engineering
Languages : en
Pages : 193
Book Description
The Science & Applications of Heat and Mass Transfer: Reports, Reviews, & Computer Programs, Volume 6: Turbulent Buoyant Jets and Plumes focuses on the formation, properties, characteristics, and reactions of turbulent jets and plumes. The selection first offers information on the mechanics of turbulent buoyant jets and plumes and turbulent buoyant jets in shallow fluid layers. Discussions focus on submerged buoyant jets into shallow fluid, horizontal surface or interface jets into shallow layers, fundamental considerations, and turbulent buoyant jets (forced plumes). The manuscript then examines a turbulence model for buoyant flows and its application to vertical buoyant jets, including mathematical model, calculation of vertical buoyant jets, and explanation of velocity and temperature spreading in pure jets and pure plumes. The publication is a dependable reference for scientists and readers interested in turbulent buoyant jets and plumes.
Numerical Modeling of Laser-induced Plumes and Jets
Author: Austin PalyaPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 162
Book Description
The goal of the current work is to perform numerical modeling and identify important phenomena associated with vapor plume and jet flows induced by irradiation of metal targets with short pulse or continuous wave (CW) lasers, discover and explain the mechanisms responsible for vaporized material motion in applications of lasers for material processing and analysis such as deep laser drilling, laser-induced breakdown spectroscopy (LIBS), and selective laser melting (SLM) of metallic powders. The simulations of laser-induced vapor expansion into a background gas are performed with a combined computational model, including the thermal model of irradiated targeted and a kinetic model of multi-component gas flows. The latter is implemented for simulations in the form of the Direct Simulation Monte Carlo method. Based on this model, two major problems are considered. In the first problem, vapor plume expansion under conditions of spatial confinement when the plume, which is induced by irradiation of a copper target by a short-pulse laser, propagates inside a cavity or trench, is considered. The simulations identify two major effects, the focusing effect, appearing due to transient motion of shock waves inside the cavity, and the confinement effect, induced due to overall deceleration of the plume with increasing background gas pressure, as two major mechanisms affecting removal of vaporized material out of the cavity and formation of high-density and high-temperature regions in the plume core. Due to the trade-off between these effects, an optimum background gas pressure exists, when the efficiency of the vapor removal from the cavity is maximized. At later stages of plume expansion, the simulations also reveal a suction effect, when the vapor flow at the cavity throat can be temporarily directed into the cavity, inducing a decrease of the overall efficiency of vapor removal. The balance between the focusing and confinement effects is studied in a range of the background gas pressure, for various background gas species, and various geometrical parameters of the cavity and laser beam. It is also shown that application of double laser pulses with short inter-pulse separation can be beneficial for both laser drilling and LIBS. In the second problem, a vapor jet induced by irradiation of a stainless steel target by a CW laser is simulated under conditions specific for SLM of metallic powders. The generated vapor jet is then used to predict motion of powder particles that can be efficiently entrapped into the ambient gas flow induced by the vapor jet. It is shown that powder particles in a broad range of their diameters can be efficiently entrained into the gas flow and, thus, removed from the irradiated surface. These results are in agreement with experimental observations of the surface denudation effect in SLM.
Numerical and Analytical Studies of Single and Multiphase Starting Jets and Plumes
Author: Ruo-Qian WangPublisher:
ISBN:
Category :
Languages : en
Pages : 195
Book Description
Multiphase starting jets and plumes are widely observed in nature and engineering systems. An environmental engineering example is open-water disposal of sediments. The present study numerically simulates such starting jets/plumes using Large Eddy Simulations. The numerical scheme is first validated for single phase plumes, and the relationship between buoyancy and penetration rate is revealed. Then, the trailing stem behind the main cloud is identified, and the the formation number (critical ratio U[delta]t/D, where U, D and [delta]t are discharge velocity, diameter and duration) that determines its presence is determined as a function of plume buoyancy. A unified relationship for starting plumes is developed to describe behaviors from negative to positive buoyancy. In multiphase simulations, two-phase phenomena are clarified including phase separation and the effect of particle release conditions. The most popular similarity law to scale up from the lab to the field (Cloud number scaling) is validated by a series of simulations. Finally, an example of sediment disposal in the field is given based on the present study. In related theoretical analysis, an analytical model on the vortex ring is developed and found to agree well with the direct numerical simulation results.
Numerical Modeling of Chemistry, Turbulent Mixing and Aerosol Dynamics in Near-field Aircraft Plumes
Author: Zheng WangA Numerical and Experimental Study of Turbulent Single and Multiphase Forced Plumes and Jets at Moderate Reynolds Numbers
Author: Gordon N. TaubPublisher:
ISBN:
Category :
Languages : en
Pages : 164
Book Description
Flows where a narrow body of fluid, carried by initial momentum or buoyancy, entrains an ambient fluid are common in the environment. Volcanoes, smoke exiting a chimney or rising from a forest fire, tornadoes and deep water oil spills are just a few examples. If the main driving force is momentum we term such a flow a jet. On the other hand, if the main driving force is buoyancy we typically refer to the flow as a plume. Perhaps more common, initial momentum and buoyancy are both present in which case we can refer to the flow as either a buoyant jet or a forced plume. Forced plumes can be either single phase, where buoyancy is caused by either a difference in temperature or some other scalar phenomenon, or multiphase where buoyancy is due to the injection of particles, bubbles or drops of material other than the ambient fluid into the flow. In this study single and multiphase jets and plumes will be examined. A laminar study will be presented which examines the effect of the addition of a small amount of nonzero angular momentum to jets and plumes. The results of direct numerical simulations of a pure jet, a pure plume and a forced plume, in the turbulent, moderate Reynolds number regime are presented and compared. Each simulation was run long enough so that time averaged third order statistics converged, allowing each term of the turbulent kinetic energy equation and Reynolds stress transport equations to be calculated directly. The results of laboratory experiments of a pure jet and multiphase plume, conducted at Ecole Nationale Superieure De Mecanique et D'Aerotechnique (ENSMA) located in Poitiers, France will be presented. Preliminary results of multiphase plume simulations using the Equilibrium-Eulerian technique will be discussed.
Numerical Simulation of Effluent Discharges
Author: Abdolmajid MohammadianPublisher: CRC Press
ISBN: 1000819744
Category : Technology & Engineering
Languages : en
Pages : 127
Book Description
Numerical Simulation of Effluent Discharges: Applications with OpenFOAM provides a resource for understanding the effluent discharge mechanisms and the approaches for modeling them. It bridges the gap between academia and industry with a focused approach in CFD modeling and providing practical examples and applications. With a detailed discussion on performing numerical modeling of effluent discharges in various ambient waters and with different discharge configurations, the book covers the application of OpenFOAM in effluent discharge modeling. Features: Discusses effluent discharges into various ambient waters with different discharge configurations. Focuses on numerical modeling of effluent discharges. Covers the fundamentals in predicting the mixing characteristics of effluents resulting from desalination plants. Reviews the past CFD studies on the effluent discharge modeling thoroughly. Provides guidance to researchers and engineers on the future steps in modeling of effluent discharges. Includes an introduction to OpenFOAM and its application in effluent discharge modeling. The book will benefit both academics and professional engineers practicing in the area of environmental fluid mechanics and working on the effluent discharge modeling. Chapter 3 of this book is available for free in PDF format as Open Access from the individual product page at www.routledge.com. It has been made available under a Creative Commons Attribution-Non Commercial-No Derivatives 4.0 license.
Author: S. Paul Pao