Understanding Of Fluid Mechanics Research Articles

Technical Perspective of Carbon Capture, Utilization, and Storage

Carbon dioxide (CO 2 ) is the primary greenhouse gas contributing to anthropogenic climate change which is associated with human activities. The majority of CO 2 emissions are results of the burning of fossil fuels for energy, as well as industrial processes such as steel and cement production. Carbon capture, utilization, and storage (CCUS) is a sustainable technology promising in terms of reducing CO 2 emissions that would otherwise contribute to climate change. From this perspective, the discussion on carbon capture focuses on chemical absorption technology, primarily due to its commercialization potential. The CO 2 absorptive capacity and absorption rate of various chemical solvents have been summarized. The carbon utilization focuses on electrochemical conversion routes converting CO 2 into potentially valuable chemicals which have received particular attention in recent years. The Faradaic conversion efficiencies for various CO 2 reduction products are used to describe efficiency improvements. For carbon storage, successful deployment relies on a better understanding of fluid mechanics, geomechanics, and reactive transport, which are discussed in details.

Hydrodynamics in Cell Studies.

Hydrodynamic phenomena are ubiquitous in living organisms and can be used to manipulate cells or emulate physiological microenvironments experienced in vivo. Hydrodynamic effects influence multiple cellular properties and processes, including cell morphology, intracellular processes, cell–cell signaling cascades and reaction kinetics, and play an important role at the single-cell, multicellular, and organ level. Selected hydrodynamic effects can also be leveraged to control mechanical stresses, analyte transport, as well as local temperature within cellular microenvironments. With a better understanding of fluid mechanics at the micrometer-length scale and the advent of microfluidic technologies, a new generation of experimental tools that provide control over cellular microenvironments and emulate physiological conditions with exquisite accuracy is now emerging. Accordingly, we believe that it is timely to assess the concepts underlying hydrodynamic control of cellular microenvironments and their applications and provide some perspective on the future of such tools in in vitro cell-culture models. Generally, we describe the interplay between living cells, hydrodynamic stressors, and fluid flow-induced effects imposed on the cells. This interplay results in a broad range of chemical, biological, and physical phenomena in and around cells. More specifically, we describe and formulate the underlying physics of hydrodynamic phenomena affecting both adhered and suspended cells. Moreover, we provide an overview of representative studies that leverage hydrodynamic effects in the context of single-cell studies within microfluidic systems.

On the transient flow characteristics in Confined Impinging Jet Mixers ‐ CFD simulation and experimental validation

Confined impinging jet reactors (CIJMs) are very efficient mixing devices. Due to the generation of high turbulent dissipation and, thus, intensive mixing of two colliding liquid flows CIJMs are widely used in laboratory applications. Besides low construction effort, these mixers enable a sensitive control of fast reactions, an efficient initial homogenization of educts and consequently a rapid build-up of supersaturation as the driving force for precipitation and crystallization. The understanding of fluid mechanics and mixing in those CIJMs is of fundamental interest for a proper description of parallel or consecutive processes. Therefore, this paper gives an insight into characteristic procedures, with the main focus on the turbulent flow regime in a T- and Y-CIJM. Experimental investigation on the local mixing behavior of liquid-phase impinging jets in static mixers is carried out by using an optical laser induced fluorescence (LIF) and particle image velocimetry (PIV) setup. In order to avoid optical measurement errors due to the cylindrical geometry, a refractive index correction of fluids with the ionic additive NH4SCN has been carried out. Due to poor information in literature, important properties of the corrected aqueous solution are listed. Another main focus of this work lies in the mathematical modeling of the flow field based on computational fluid dynamics (CFD) methods. The transient hybrid Detached Eddy-SST-k–ω turbulence approach is introduced as a computational cost-efficient highly accurate method to calculate flow conditions in turbulent CIJMs. LIF and PIV as well as pressure drop measurements provide a wide set of data that serve to validate CFD simulations.

Development of Efficient Designs of Cooking Systems. II. Computational Fluid Dynamics and Optimization

Sections 2–6 of Part I were devoted to the analysis of heat transfer characteristics of cookers. In all the experiments, only water was employed as a working medium. Now, we extend such an analysis to the actual cooking process in order to arrive at an improved cooking device. The major strategies for the optimization of energy utilization is to design appropriate insulation that has been obtained by two cover vessels. In order to select an air gap, the flow and temperature patterns in the air gap have been extensively analyzed using computational fluid dynamics (CFD). The flow pattern and heat transfer in cooking pots have also been analyzed by CFD. This has enabled us to design suitable internals for minimizing the stratification of temperature. The understanding of fluid mechanics has also given basis for selection of heat flux, gap between burner tip and cooker bottom, and temperature of flue gases leaving the cooker. Chemical engineering principles have been used for modeling and optimization. Kinetics have been obtained in batch cookers. The knowledge of kinetics, thermal mixing, axial mixing, and optimum selection of insulation have been employed for the development of continuous cookers. The continuous mode of operation also helps in saving of energy. Systematic data have been collected for the design and scale up of continuous cookers.

Enhancing the Learning of Fluid Mechanics Using Computer Simulations

AbstractThis paper reports the results of a study into the impact of computer simulations on the understanding of fluid mechanics by engineering students. A “lesson study” approach was taken, using constructivist educational theory combined with the variation theory of learning from phenomenography to inform the design of learning activities and to assess their impact. Student difficulties with fluid mechanics concepts were assessed using questions from the Fluid Mechanics Concept Inventory (FMCI). Students had the greatest difficulties with pressure measurement, fluid flow through pipes with changing diameter, and velocity profiles for fluid between flat plates. We developed a set of three simulations to address these difficulties. The impact of the simulations was gauged by a second administration of the FMCI. Most of the students in the sophomore fluid mechanics class participated in the whole of this exercise. Students showed significant improvement in two of the three areas of difficulty. Student feedback on this as an additional learning exercise was very positive.

SIR JAMES LIGHTHILL

James Lighthill died on 17 July 1998, at the end of a ten-hour swim round the Channel Island of Sark. He had earlier, at age 49, been the first person ever to do this, and he was carrying out the swim for the seventh time when the exertion revealed a mitral valve weakness which had never been diagnosed, and which led to his sudden death in the water. The swim was one of many long ‘adventure swims’ which Lighthill liked to take, all characterized by strong tidal currents and often heavy seas. And Lighthill took much pleasure through exercising his comprehensive understanding of fluid mechanics first in preparing for them through study of local conditions and then in adapting his performance when, as often, he found that in practice the currents were not as charted and, in fact, often more treacherous.Many obituary notices have already appeared in the national press in the UK and USA, and now in the newsletters and journals of learned societies; and extensive conspectuses of Lighthill's contributions to fluid mechanics and applied mathematics, and to science generally and to the administration of science, will be published in Annual Review of Fluid Mechanics (2000), and in Biographical Memoirs of Fellows of the Royal Society (2000). The reader will learn, from those accounts, of the unique range and depth of Lighthill's contributions; and virtually all readers should expect to be surprised and impressed to read of facets of Lighthill's work of which they were previously totally unaware.

FLOW STRUCTURES AND HEAT TRANSFER DURING TRANSITION IN PERTURBED MIXED-CONVECTION CHANNEL FLOWS

This research seeks to increase our understanding of fluid mechanics and heat transfer phenomena in transitional mixed-convection flows between two heated vertical plates. A direct numerical simulation by the spectral method with weak formulation is used to solve the transient three-dimensional (3-D) Navier-Stokes equations and energy equation. Initial disturbances consist of the finite amplitude two-dimensional Tollmien-Schlichting wave and two 3-D oblique waves. The Nusselt number (Nu) is mainly a function of the Rayleigh number (Ra) and also depends on the Reynolds number (Re) and the Richardson number (Ri). Nu dependence on Re increases with increase of Ra. Disturbance competitions among different modes during transition are shown for different sets of dimensionless parameters. Flow visualization by passive particles is also presented.

Jaime Amorocho 1920”1983

Jim made his initial major contribution to hydrology with his Ph.D. dissertation, in which he developed a mathematical modeling procedure for nonlinear analysis of hydrologic systems. He continued the use of mathematical modeling procedures to analyze hydrologic problems throughout his career, including the novel application of entropy to assess uncertainty in hydrologic systems. The availability of new technologies always fascinated him. He developed practical procedures to analyze rainfall from satellite imagery. His broad interests led him to direct the construction and operation of a snowmelt lysimeter for field studies of mountain snowpacks for fundamental work in snow hydrology. He contributed much to the basic understanding of fluid mechanics and hydraulics through hydraulic model studies of significant structures, including flows in natural channels, sediment transport in rivers, and wind shear effects on flow in large open channels. He was an early developer and user of a laser Doppler flow velocity meter, which he and colleagues used extensively in studies of fundamental fluid mechanics. His research activity embraced broad areas of hydrology and hydraulic engineering.

Concepts on the pathogenesis of middle ear effusions.

Several concepts related to the pathogenesis of middle ear effusions are postulated. The mechanisms proposed are based on an understanding of fluid mechanics. A flask with a long, narrow neck is presented as a model of the Eustachian tube-middle ear-mastoid system. Fluid flow into and out of the flask is dependent upon the pressure gradient, compliance of the narrow neck and whether or not the bulbous portion is intact. It is suggested that locking of the tube may be dependent upon the speed of the application of the negative pressure and the compliance. Eustachian tube opening appears to be related not only to active muscle forces but may also be dependent upon the presence of a pressure gradient which passively assists tubal function. It is proposed that middle ear effusions result from reflux, aspiration or insufflation of nasopharyngeal secretions (acute otitis media), or from persistent functional or mechanical Eustachian tube obstruction (secretory otitis media) or both.

Habitat of Oil in Carbonate Rocks: ABSTRACT

Entrapment of oil in carbonate reservoirs can be explained by analysis of (a) depositional environment, (b) diagenetic changes, (c) structural history, and (d) fluid mechanics. Favorable reservoir rocks in carbonate environments include reefs, bioherms, oolite bars, and porous skeletal calcarenite. Production of organic material in such environments (with the exception of oolite bars) is prolific, but under normal conditions a major part of the organic soft parts are destroyed by bacteria scavengers and early diagenesis, whereas skeletal parts are preserved. Early diagenesis modifies the texture and the original porosity of carbonate deposits by recrystallization, solution, cementation, and replacement. Under favorable conditions, dolomitization enhances the reservoir characteristics of the carbonate sediment. Hydrocarbons are found in cyclic carbonates which were deposited on unstable shelves and subjected to recurrent sea-level fluctuations with periodic influxes of terrigenous clastic material. Under a cyclic regime of sedimentation, a reservoir-type carbonate facies can be covered by sapropelic shale, evaporite, or basinal facies. This stratigraphic relation, in addition to providing an adequate seal, also can be suitable to preservation of organic soft parts within the reservoir facies. In the writer's opinion, cyclic sedimentation in carbonate rocks could explain in situ accumulation of hydrocarbons in carbonate rocks under certain favorable conditions. The oil generated in carbonate rocks is subject to secondary migration as a result of structural deformation. An understanding of fluid mechanics is very useful for explanation of some peculiarities of oil distribution within the carbonate traps. Tectonic setting of the carbonate shelf, relative to the stable nuclei and the mobile margins of the continents, has a profound influence on the type of trapping mechanisms likely to be found in the carbonate rocks. End_of_Article - Last_Page 1831------------