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Turbulence: Numerical Analysis, Modelling and Simulation

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ISBN: 9783038428091 9783038428107 Year: Pages: VI, 222 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Physics (General) --- Mathematics
Added to DOAB on : 2018-05-04 10:38:08
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The problem of accurate and reliable simulation of turbulent flows is a central and intractable challenge that crosses disciplinary boundaries. As the needs for accuracy increase and the applications expand beyond flows where extensive data is available for calibration, the importance of a sound mathematical foundation that addresses the needs of practical computing increases. This Special Issue is directed at this crossroads of rigorous numerical analysis, the physics of turbulence and the practical needs of turbulent flow simulations. It seeks papers providing a broad understanding of the status of the problem considered and open problems that comprise further steps.

Optimizing Dual-Doppler Lidar Measurements of Surface Layer Coherent Structures with Large-Eddy Simulations

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Book Series: Wissenschaftliche Berichte des Instituts für Meteorologie und Klimaforschung des Karlsruher Instituts für Technologie ISSN: 1795619 ISBN: 9783731501978 Year: Volume: 64 Pages: 234 p. DOI: 10.5445/KSP/1000039726 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Physics (General)
Added to DOAB on : 2019-07-30 20:02:02
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Coherent structures are patterns in the wind field of the atmospheric boundary layer. The deployment of two scanning Doppler lidars facilitates the measurement of the horizontal wind field, but the inherent averaging processes complicate an interpretation of the results. To assess the suitability of this technique for coherent structure detection large-eddy simulations are used as a basis for virtual measurements, and the effects of the lidar technique on the wind field structure are analyzed.

The Atmosphere over Mountainous Regions

Authors: --- --- --- --- et al.
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889450169 Year: Pages: 160 DOI: 10.3389/978-2-88945-016-9 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Geography
Added to DOAB on : 2018-02-27 16:16:44
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Mountainous regions occupy a significant fraction of the Earth’s continents and are characterized by specific meteorological phenomena operating on a wide range of scales. Being a home to large human populations, the impact of mountains on weather and hydrology has significant practical consequences. Mountains modulate the climate and create micro-climates, induce different types of thermally and dynamically driven circulations, generate atmospheric waves of various scales (known as mountain waves), and affect the boundary layer characteristics and the dispersion of pollutants. At the local scale, strong downslope winds linked with mountain waves (such as the Foehn and Bora) can cause severe damage. Mountain wave breaking in the high atmosphere is a source of Clear Air Turbulence, and lee wave rotors are a major near-surface aviation hazard. Mountains also act to block strongly-stratified air layers, leading to the formation of valley cold-air pools (with implications for road safety, pollution, crop damage, etc.) and gap flows. Presently, neither the fine-scale structure of orographic precipitation nor the initiation of deep convection by mountainous terrain can be resolved adequately by regional-to global-scale models, requiring appropriate downscaling or parameterization. Additionally, the shortest mountain waves need to be parameterized in global weather and climate prediction models, because they exert a drag on the atmosphere. This drag not only decelerates the global atmospheric circulation, but also affects temperatures in the polar stratosphere, which control ozone depletion. It is likely that both mountain wave drag and orographic precipitation lead to non-trivial feedbacks in climate change scenarios. Measurement campaigns such as MAP, T-REX, Materhorn, COLPEX and i-Box provided a wealth of mountain meteorology field data, which is only starting to be explored. Recent advances in computing power allow numerical simulations of unprecedented resolution, e.g. LES modelling of rotors, mountain wave turbulence, and boundary layers in mountainous regions. This will lead to important advances in understanding these phenomena, as well as mixing and pollutant dispersion over complex terrain, or the onset and breakdown of cold-air pools. On the other hand, recent analyses of global circulation biases point towards missing drag, especially in the southern hemisphere, which may be due to processes currently neglected in parameterizations. A better understanding of flow over orography is also crucial for a better management of wind power and a more effective use of data assimilation over complex terrain. This Research Topic includes contributions that aim to shed light on a number of these issues, using theory, numerical modelling, field measurements, and laboratory experiments.

Flow and Heat or Mass Transfer in the Chemical Process Industry

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ISBN: 9783038972389 9783038972396 Year: Pages: 214 DOI: 10.3390/books978-3-03897-239-6 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: General and Civil Engineering
Added to DOAB on : 2018-09-28 12:14:25
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ca. 200 words; this text will present the book in all promotional forms (e.g. flyers). Please describe the book in straightforward and consumer-friendly terms.[Flow through process equipment in a chemical or manufacturing plant (e.g., heat exchangers, reactors, catalyst regeneration units, separation units, pumps, pipes, smoke stacks, etc.) is usually coupled with heat and/or mass transfer. Rigorous investigation of this coupling of momentum, heat, and mass transfer is not only important for the practice of designing process equipment, but is also important for improving our overall theoretical understanding of transfer phenomena. While generalizations and empiricisms, like the concept of the heat transfer coefficient or the widely used Reynolds analogy in turbulence, or the use of empirical transfer equations for flow in separation towers and reactors packed with porous media, have served practical needs in prior decades, such empiricisms can now be revised or altogether replaced by bringing modern experimental and computational tools to bear in understanding the interplay between flow and transfer. The patterns of flow play a critical role in enhancing the transfer of heat and mass. Typical examples are the coherent flow structures in turbulent boundary layers, which are responsible for turbulent transfer and mixing in a heat exchanger and for dispersion from a smoke stack, and the flow patterns that are a function of the configuration of a porous medium and are responsible for transfer in a fixed bed reactor or a fluid bed regenerator unit. The goal of this Special Issue is to be a forum for recent developments in theory, state-of-the-art experiments and computations on the interactions between flow and transfer in single and multi-phase flow, and from small scales to large scales, which can be important for the design of equipment in a chemical processing plant.]

Progress in Combustion Diagnostics, Science and Technology

Authors: --- ---
ISBN: 9783039285105 9783039285112 Year: Pages: 336 DOI: 10.3390/books978-3-03928-511-2 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2020-04-07 23:07:09
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The role that combustion plays in the world’s energy systems will continue to evolve with the changes in technological demands. For example, the challenges that we face today are more focused on the conservation of energy and addressing environmental concerns, which together necessitate cleaner and more efficient combustion processes using a range of fuel sources. This book includes contributions to highlight the recent progress in theory and experiments, development, and demonstration of technologies and systems involving combustion processes, for the production, storage, use, and conservation of energy.

Keywords

steam ejector --- wet steam model --- computational fluid dynamics --- condensation effect --- fire suppression system --- acoustic --- frequency --- NOx emission index --- flame length --- global residence time --- flow-field --- flame-front --- gasoline engine --- flame propagation --- turbulence --- PPCI diesel engine --- pilot injection --- combustion noise --- stationary wavelet packet transform --- stationary wavelet transform --- CO2 emission --- gasoline vehicles --- electric vehicles --- driving cycles --- vehicle dynamic model --- High speed PIV --- flame propagation --- planer laser tomography --- micro-scale combustion --- diffusion flames --- micro power generation --- numerical investigations --- fire whirl --- computational fluid dynamics --- eddy-generation mechanism --- combustion modelling --- detailed chemistry --- large eddy simulation --- combustion waste heat --- experiment --- steam ejector --- shock-mixing layer --- flow structure --- operating parameter --- combustion waste heat --- steam ejector --- shock wave --- entrainment ratio --- pumping performance --- critical back pressure --- hot jet detonation initiation technique --- flame acceleration --- detonation combustion --- vortex --- ignition position --- hydrogen --- internal combustion engine --- compression ignition --- dual-fuel engine --- direct injection --- high pressure gas jet --- jet penetration --- fuel injector --- CI engine --- biofuel --- fuel combustion --- combustion --- alternative fuel --- canola oil (Co) --- diesel engine --- common rail --- diesel fuel (Df) --- n-hexane --- injection --- tunable diode laser absorption tomography --- exhaust gas --- temperature --- similarity analysis --- Mahalanobis distance --- root mean square error --- fire whirl --- computational fluid dynamics --- eddy-generation mechanism --- combustion modelling --- detailed chemistry --- large eddy simulation --- engine valve systems --- continuously variable valve systems --- engine valve system control --- combustion optimization

Computational Aerodynamic Modeling of Aerospace Vehicles

Authors: ---
ISBN: 9783038976103 Year: Pages: 294 DOI: 10.3390/books978-3-03897-611-0 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering --- Transportation
Added to DOAB on : 2019-03-08 11:42:05
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Currently, the use of computational fluid dynamics (CFD) solutions is considered as the state-of-the-art in the modeling of unsteady nonlinear flow physics and offers an early and improved understanding of air vehicle aerodynamics and stability and control characteristics. This Special Issue covers recent computational efforts on simulation of aerospace vehicles including fighter aircraft, rotorcraft, propeller driven vehicles, unmanned vehicle, projectiles, and air drop configurations. The complex flow physics of these configurations pose significant challenges in CFD modeling. Some of these challenges include prediction of vortical flows and shock waves, rapid maneuvering aircraft with fast moving control surfaces, and interactions between propellers and wing, fluid and structure, boundary layer and shock waves. Additional topic of interest in this Special Issue is the use of CFD tools in aircraft design and flight mechanics. The problem with these applications is the computational cost involved, particularly if this is viewed as a brute-force calculation of vehicle’s aerodynamics through its flight envelope. To make progress in routinely using of CFD in aircraft design, methods based on sampling, model updating and system identification should be considered.

Keywords

wake --- bluff body --- square cylinder --- DDES --- URANS --- turbulence model --- large eddy simulation --- Taylor–Green vortex --- numerical dissipation --- modified equation analysis --- truncation error --- MUSCL --- dynamic Smagorinsky subgrid-scale model --- kinetic energy dissipation --- computational fluid dynamics (CFD) --- microfluidics --- numerical methods --- gasdynamics --- shock-channel --- microelectromechanical systems (MEMS) --- discontinuous Galerkin finite element method (DG–FEM) --- fluid mechanics --- characteristics-based scheme --- multi-directional --- Riemann solver --- Godunov method --- bifurcation --- wind tunnel --- neural networks --- modeling --- unsteady aerodynamic characteristics --- high angles of attack --- hypersonic --- wake --- chemistry --- slender-body --- angle of attack --- detection --- after-body --- S-duct diffuser --- flow distortion --- flow control --- vortex generators --- aeroelasticity --- reduced-order model --- flutter --- wind gust responses --- computational fluid dynamics --- convolution integral --- sharp-edge gust --- reduced order aerodynamic model --- geometry --- meshing --- aerodynamics --- CPACS --- MDO --- VLM --- Euler --- CFD --- variable fidelity --- multi-fidelity --- aerodynamic performance --- formation --- VLM --- RANS --- hybrid reduced-order model --- quasi-analytical --- aeroelasticity --- flexible wings --- subsonic --- wing–propeller aerodynamic interaction --- p-factor --- installed propeller --- overset grid approach

Intermittency and Self-Organisation in Turbulence and Statistical Mechanics

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ISBN: 9783039211081 9783039211098 Year: Pages: 298 DOI: 10.3390/books978-3-03921-109-8 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Mathematics
Added to DOAB on : 2019-08-28 11:21:27
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There is overwhelming evidence, from laboratory experiments, observations, and computational studies, that coherent structures can cause intermittent transport, dramatically enhancing transport. A proper description of this intermittent phenomenon, however, is extremely difficult, requiring a new non-perturbative theory, such as statistical description. Furthermore, multi-scale interactions are responsible for inevitably complex dynamics in strongly non-equilibrium systems, a proper understanding of which remains a main challenge in classical physics. As a remarkable consequence of multi-scale interaction, a quasi-equilibrium state (the so-called self-organisation) can however be maintained. This special issue aims to present different theories of statistical mechanics to understand this challenging multiscale problem in turbulence. The 14 contributions to this Special issue focus on the various aspects of intermittency, coherent structures, self-organisation, bifurcation and nonlocality. Given the ubiquity of turbulence, the contributions cover a broad range of systems covering laboratory fluids (channel flow, the Von Kármán flow), plasmas (magnetic fusion), laser cavity, wind turbine, air flow around a high-speed train, solar wind and industrial application.

Multiscale Turbulent Transport

Authors: ---
ISBN: 9783039282128 9783039282135 Year: Pages: 210 DOI: 10.3390/books978-3-03928-213-5 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2020-04-07 23:07:08
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Turbulent transport is currently a prominent and ongoing investigation subject at the interface of methodologies from theory to numerical simulations and experiments, and it covers several spatiotemporal scales. Mathematical analysis, physical modelling, and engineering applications represent different facets of a classical, long-standing problem that is still far from being thoroughly comprehended. The goal of this Special Issue is to outline recent advances of such subjects as multiscale analysis in turbulent transport processes, Lagrangian and Eulerian descriptions of turbulence, advection of particles and fields in turbulent flows, ideal or nonideal turbulence (unstationary/inhomogeneous/anisotropic/compressible), turbulent flows in biofluid mechanics and magnetohydrodynamics, and the control and optimization of turbulent transport. The SI is open to regular articles, review papers focused on the state of the art and the progress made over the last few years, and new research trends.

Recent Advances in Urban Ventilation Assessment and Flow Modelling

Authors: ---
ISBN: 9783038978060 9783038978077 Year: Pages: 448 DOI: 10.3390/books978-3-03897-807-7 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General)
Added to DOAB on : 2019-04-25 16:37:17
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This book contains twenty-one original papers and one review paper published by internationally recognized experts in the Atmosphere Special Issue ""Recent Advances in Urban Ventilation Assessment and Flow Modelling"", years 2017–2019. The Special Issue includes contributions on recent experimental and modelling works, techniques, and developments mainly tailored to the assessment of urban ventilation on flow and pollutant dispersion in cities. The study of ventilation is of critical importance, as it addresses the capacity with which a built urban structure is capable of replacing the polluted air with ambient fresh air. Here, ventilation is recognized as a transport process that improves local microclimate and air quality and closely relates to the term “breathability”. The efficiency with which street canyon ventilation occurs depends on the complex interaction between the atmospheric boundary layer flow and the local urban morphology.The individual contributions to this Issue are summarized and categorized into four broad topics: (1) outdoor ventilation efficiency and application/development of ventilation indices, (2) relationship between indoor and outdoor ventilation, (3) effects of urban morphology and obstacles to ventilation, and (4) ventilation modelling in realistic urban districts. The results and approaches presented and proposed will be of great interest to experimentalists and modelers, and may constitute a starting point for the improvement of numerical simulations of flow and pollutant dispersion in the urban environment, for the development of simulation tools, and for the implementation of mitigation strategies.

Keywords

street canyon --- seasonal variation --- air flow --- pollutant dispersion --- pollutant removal --- natural ventilation --- residential wind environments --- building arrangements --- space pattern --- ventilation efficiency --- CFD simulation --- air change rate (ACH) --- flow and turbulence profiles --- hypothetical urban areas --- street-level ventilation --- ventilation assessment --- wind-tunnel dataset --- street vegetation --- CFD --- aerodynamic and deposition --- tree scenarios --- urban planning --- indoor-outdoor --- mass concentration --- nanoparticles --- particle number concentration (PNC) --- PM10 --- PM2.5 --- sampling --- Total Suspended Particles (TSP) --- ultrafine particles (UFP) --- urban street canyon --- wind enhancement --- architectural intervention --- water channel experiment --- CFD simulation --- passive ventilation --- street canyon --- computational fluid dynamics (CFD) --- ventilation effectiveness --- the age of air --- convective boundary layer --- LES --- street-level ventilation --- small open space --- air change rate per hour (ACH) --- concentration decay method --- urban age of air --- computational fluid dynamic (CFD) simulation --- natural ventilation --- residential building --- climate zone --- thermal comfort --- natural ventilation hour --- Japan cities --- building energy use --- inter-building effect --- highly-reflective building envelope --- BEopt analysis --- source apportionment --- data assimilation --- urban air quality modelling --- wind environment --- Natural Ventilation Potential (NVP) --- PM2.5 --- building–tree grouping patterns --- Computational Fluid Dynamics (CFD) --- LES --- ventilation --- urban planning --- dispersion --- air quality --- street canyon --- traffic tidal flow --- numerical simulation --- vehicular pollution --- non-uniform distribution of the pollution source --- on-road air quality --- traffic composition --- high emitting vehicles --- street canyon --- mobile laboratory --- CFD model --- heat loss --- optimisation --- residential building --- air quality --- carbon dioxide concentration --- ventilation system --- wind pressure coefficient --- airflow network --- multiple linear regression --- natural ventilation --- urban layout --- surrogate model --- schematic urban environment --- wind tunnel --- LES --- validation --- street canyon --- coherent structures --- road tunnel --- natural ventilation --- wind catcher --- intake fraction --- street canyon --- CFD --- Large Eddy Simulation (LES) --- urban air quality --- pedestrian exposure --- concentration fluctuation --- outdoor ventilation --- urban morphology --- building site coverage --- ventilation efficiency --- n/a

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