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Large-eddy simulation --- Dissertations [Academic ] --- Transfert de chaleur conjugué --- Dissertations [Academic ] --- Gas-turbines --- Cooling --- Dissertations [Academic ]

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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.

Turbulent fluxes --- Downslope winds --- Large eddy simulation --- Sub-mesoscale circulations --- orographic precipitation --- Thermally-driven flows --- Horizontal inhomogeneity --- Cold air pools --- Hydraulic jumps --- mountain waves

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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.

Turbulent fluxes --- Downslope winds --- Large eddy simulation --- Sub-mesoscale circulations --- orographic precipitation --- Thermally-driven flows --- Horizontal inhomogeneity --- Cold air pools --- Hydraulic jumps --- mountain waves --- Turbulent fluxes --- Downslope winds --- Large eddy simulation --- Sub-mesoscale circulations --- orographic precipitation --- Thermally-driven flows --- Horizontal inhomogeneity --- Cold air pools --- Hydraulic jumps --- mountain waves

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This Special Issue highlights the latest enhancements in the abatement of noise and vibrations in aerospace and automotive systems. The reduction of acoustic emissions and the improvement of interior cabin comfort desired by all major transportation industries, as these areas have a direct impact on customer satisfaction and, consequently, the commercial success of new products. Topics covered in this Special Issue deal with computational approaches, instrumentation and data analysis related to noise and vibrations of fixed-wing aircraft, satellites, spacecraft, automobiles, and trains, covering aerodynamically generated noise, engine noise, sound absorption, cabin acoustic treatments, duct acoustics, and vibroacoustic properties of materials. This Special Issue also focuses on industrial aspects. Existing procedures and algorithms that are useful in reaching the abovementioned objectives in the most efficient way are illustrated in the collected papers.

History of engineering & technology --- flexible spacecraft --- periodic disturbance compensation --- compensate torque design --- vibration attenuation --- reaction wheel. --- vibration analysis --- FEM --- multibody simulations --- Plasma flow control --- multichannel discharge --- plasma synthetic actuator --- actuator array --- analytic model --- centrifugal fan --- unsteady flow --- vibroacoustics --- fluid-structure-acoustic coupling --- optimization --- high-speed train --- pantograph --- aerodynamic noise --- large eddy simulation --- acoustic finite element method --- transonic buffet --- tangential slot --- steady and periodic blowing --- postpone of buffet onset --- buffet load alleviation --- component mode synthesis --- petrol engine --- NVH --- FRF --- leakage location --- Lamb wave --- beamforming --- spacecraft in orbit --- vibro-acoustics --- MDO --- aircraft fuselage --- aeroacoustics --- acoustics --- noise --- vibration --- aeronautics --- automotive

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The air pollution problem inevitably accompanies our human activities. Severe air pollution situations have been reported, especially in emerging countries, and satisfying the air quality standards fully remains an underlying issue. Today, modeling research is one of the more valuable approaches to understanding the behavior of air pollutants, and is useful for regulation-, policy- and decision-making. Such modeling applications range, with regard to horizontal grid resolution, from a few km (local) to hundreds of km (regional), to thousands of km (global). To foster our current scientific knowledge on modeling potentialities and limitations, scientific research related to multi-scale air pollution modeling is collected in this book.

Environmental science, engineering & technology --- Urban pollution --- Street canyon --- Nitrate aerosol --- CFD --- Air quality --- open burning --- biomass burning --- sugarcane crops --- environmental assessment --- air quality modeling --- chemical reaction model --- urban canyon --- radiation --- mesoscale models --- reactive pollutants --- Community Multiscale Air Quality (CMAQ) --- East Asia --- Tokyo --- SO42– --- stabilized Criegee intermediates (SCI) --- wildfire plume rise --- smoke modeling --- large eddy simulation --- emissions dispersion --- WRF-SFIRE --- RxCADRE --- RePLaT-Chaos --- large-scale atmospheric advection --- chaotic advection --- stretching rate --- escape rate --- education --- CMAQ --- PM10 --- atmospheric reanalysis --- PM2.5 --- PM2.5 components --- three-dimensional chemical transport model --- model inter-comparison --- urban scale --- secondary particles --- WRF-Chem --- visibility --- eastern China --- neural network algorithm --- IMPROVE --- n/a --- SO42 --- -stabilized Criegee intermediates (SCI)