Bibliographies thématiques / Vertical velocities

Littérature scientifique sur le sujet « Vertical velocities »

Auteur : Grafiati
Publié le 7 juillet 2024
Mis à jour le 7 juillet 2024

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Articles de revues sur le sujet "Vertical velocities"

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Vélez-Belchí, Pedro, et Joaquín Tintoré. « Vertical velocities at an ocean front ». Scientia Marina 65, S1 (30 juillet 2001) : 291–300. http://dx.doi.org/10.3989/scimar.2001.65s1291.

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Frajka-Williams, Eleanor, Charles C. Eriksen, Peter B. Rhines et Ramsey R. Harcourt. « Determining Vertical Water Velocities from Seaglider ». Journal of Atmospheric and Oceanic Technology 28, no 12 (1 décembre 2011) : 1641–56. http://dx.doi.org/10.1175/2011jtecho830.1.

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Abstract Vertical velocities in the world’s oceans are typically small, less than 1 cm s−1, posing a significant challenge for observational techniques. Seaglider, an autonomous profiling instrument, can be used to estimate vertical water velocity in the ocean. Using a Seaglider’s flight model and pressure observations, vertical water velocities are estimated along glider trajectories in the Labrador Sea before, during, and after deep convection. Results indicate that vertical velocities in the stratified ocean agree with the theoretical Wentzel–Kramers–Brillouin (WKB) scaling of w; and in the turbulent mixed layer, scale with buoyancy, and wind forcing. It is estimated that accuracy is to within 0.5 cm s−1. Because of uncertainties in the flight model, velocities are poor near the surface and deep apogees, and during extended roll maneuvers. Some of this may be improved by using a dynamic flight model permitting acceleration and by better constraining flight parameters through pilot choices during the mission.
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Merckelbach, Lucas, David Smeed et Gwyn Griffiths. « Vertical Water Velocities from Underwater Gliders ». Journal of Atmospheric and Oceanic Technology 27, no 3 (1 mars 2010) : 547–63. http://dx.doi.org/10.1175/2009jtecho710.1.

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Abstract The underwater glider is set to become an important platform for oceanographers to gather data within oceans. Gliders are usually equipped with a conductivity–temperature–depth (CTD) sensor, but a wide range of other sensors have been fitted to gliders. In the present work, the authors aim at measuring the vertical water velocity. The vertical water velocity is obtained by subtracting the vertical glider velocity relative to the water from the vertical glider velocity relative to the water surface. The latter is obtained from the pressure sensor. For the former, a quasi-static model of planar glider flight is developed. The model requires three calibration parameters, the (parasite) drag coefficient, glider volume (at atmospheric pressure), and hull compressibility, which are found by minimizing a cost function based on the variance of the calculated vertical water velocity. Vertical water velocities have been calculated from data gathered in the northwestern Mediterranean during the Gulf of Lions experiment, winter 2008. Although no direct comparison could be made with water velocities from an independent measurement technique, the authors show that, for two different heat loss regimes (≈0 and ≈400 W m−2), the calculated vertical velocity scales are comparable with those expected for internal waves and active open ocean convection, respectively. High noise levels resulting from the pressure sensor require the water velocity time series to be low-pass filtered with a cutoff period of 80 s. The absolute accuracy of the vertical water velocity is estimated at ±4 mm s−1.
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Rao, P. V., P. Vinay Kumar, M. C. Ajay Kumar et G. Dutta. « Long-term mean vertical velocity measured by MST radar at Gadanki (13.5° N, 79.2° E) ». Annales Geophysicae 27, no 2 (2 février 2009) : 451–59. http://dx.doi.org/10.5194/angeo-27-451-2009.

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Abstract. MST radars are capable of measuring vertical motion along a vertically directed beam. We present 8 years (1995–2003) averaged profile of vertical velocity in the troposphere and the lower stratosphere over Gadanki (13.5° N, 79.2° E), a tropical station. A downward mid-tropospheric w is observed with a reversal of sign around 10 km and a further reversal can also be seen at ~17 km. A significant diurnal and semidiurnal variation in vertical wind is observed for all heights with subsidence during the evening hours. Seasonal variability of vertical wind is also found to be quite appreciable. Vertical velocities have been derived using symmetric pairs of off-vertical beams and a comparison has been made with direct vertical beam measurements. Vertical components estimated from E-W and N-S radial velocities do not match and are also found to have discrepancy with direct measurements. Plausible causes of the discrepancy have been investigated with the help of some case studies. Vertical shear in horizontal wind, gradients in horizontal velocities and echo power imbalance may be some of the factors responsible for the observed discrepancy.
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Donner, Leo J., Travis A. O'Brien, Daniel Rieger, Bernhard Vogel et William F. Cooke. « Are atmospheric updrafts a key to unlocking climate forcing and sensitivity ? » Atmospheric Chemistry and Physics 16, no 20 (20 octobre 2016) : 12983–92. http://dx.doi.org/10.5194/acp-16-12983-2016.

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Abstract. Both climate forcing and climate sensitivity persist as stubborn uncertainties limiting the extent to which climate models can provide actionable scientific scenarios for climate change. A key, explicit control on cloud–aerosol interactions, the largest uncertainty in climate forcing, is the vertical velocity of cloud-scale updrafts. Model-based studies of climate sensitivity indicate that convective entrainment, which is closely related to updraft speeds, is an important control on climate sensitivity. Updraft vertical velocities also drive many physical processes essential to numerical weather prediction.Vertical velocities and their role in atmospheric physical processes have been given very limited attention in models for climate and numerical weather prediction. The relevant physical scales range down to tens of meters and are thus frequently sub-grid and require parameterization. Many state-of-science convection parameterizations provide mass fluxes without specifying vertical velocities, and parameterizations that do provide vertical velocities have been subject to limited evaluation against what have until recently been scant observations. Atmospheric observations imply that the distribution of vertical velocities depends on the areas over which the vertical velocities are averaged. Distributions of vertical velocities in climate models may capture this behavior, but it has not been accounted for when parameterizing cloud and precipitation processes in current models.New observations of convective vertical velocities offer a potentially promising path toward developing process-level cloud models and parameterizations for climate and numerical weather prediction. Taking account of the scale dependence of resolved vertical velocities offers a path to matching cloud-scale physical processes and their driving dynamics more realistically, with a prospect of reduced uncertainty in both climate forcing and sensitivity.
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Gudadze, Nikoloz, Gunter Stober et Jorge L. Chau. « Can VHF radars at polar latitudes measure mean vertical winds in the presence of PMSE ? » Atmospheric Chemistry and Physics 19, no 7 (5 avril 2019) : 4485–97. http://dx.doi.org/10.5194/acp-19-4485-2019.

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Abstract. Mean vertical velocity measurements obtained from radars at polar latitudes using polar mesosphere summer echoes (PMSEs) as an inert tracer have been considered to be non-representative of the mean vertical winds over the last couple of decades. We used PMSEs observed with the Middle Atmosphere Alomar Radar System (MAARSY) over Andøya, Norway (69.30∘ N, 16.04∘ E), during summers of 2016 and 2017 to derive mean vertical winds in the upper mesosphere. The 3-D vector wind components (zonal, meridional and vertical) are based on a Doppler beam swinging experiment using five beam directions (one vertical and four oblique). The 3-D wind components are computed using a recently developed wind retrieval technique. The method includes full non-linear error propagation, spatial and temporal regularisation, and beam pointing corrections and angular pointing uncertainties. Measurement uncertainties are used as weights to obtain seasonal weighted averages and characterise seasonal mean vertical velocities. Weighted average values of vertical velocities reveal a weak upward behaviour at altitudes ∼84–87 km after eliminating the influence of the speed of falling ice. At the same time, a sharp decrease (increase) in the mean vertical velocities at the lower (upper) edges of the summer mean altitude profile, which are attributed to the sampling issues of the PMSE due to disappearance of the target corresponding to the certain regions of motions and temperatures, prevails. Thus the mean vertical velocities can be biased downwards at the lower edge, and the mean vertical velocities can be biased upwards at the upper edge, while at the main central region the obtained mean vertical velocities are consistent with expected upward values of mean vertical winds after considering ice particle sedimentation.
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Yi, Zhang, et Oddbj�rn Engvold. « Vertical velocities and oscillations in quiescent filaments ». Solar Physics 134, no 2 (août 1991) : 275–86. http://dx.doi.org/10.1007/bf00152648.

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Sévellec, F., A. C. Naveira Garabato, J. A. Brearley et K. L. Sheen. « Vertical Flow in the Southern Ocean Estimated from Individual Moorings ». Journal of Physical Oceanography 45, no 9 (septembre 2015) : 2209–20. http://dx.doi.org/10.1175/jpo-d-14-0065.1.

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AbstractThis study demonstrates that oceanic vertical velocities can be estimated from individual mooring measurements, even for nonstationary flow. This result is obtained under three assumptions: (i) weak diffusion (Péclet number ≫ 1), (ii) weak friction (Reynolds number ≫ 1), and (iii) small inertial terms (Rossby number ≪ 1). The theoretical framework is applied to a set of four moorings located in the Southern Ocean. For this site, the diagnosed vertical velocities are highly variable in time, their standard deviation being one to two orders of magnitude greater than their mean. The time-averaged vertical velocities are demonstrated to be largely induced by geostrophic flow and can be estimated from the time-averaged density and horizontal velocities. This suggests that local time-mean vertical velocities are primarily forced by the time-mean ocean dynamics, rather than by, for example, transient eddies or internal waves. It is also shown that, in the context of these four moorings, the time-mean vertical flow is consistent with stratified Taylor column dynamics in the presence of a topographic obstacle.
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Hoppe, C. M., F. Ploeger, P. Konopka et R. Müller. « Kinematic and diabatic vertical velocity climatologies from a chemistry climate model ». Atmospheric Chemistry and Physics Discussions 15, no 21 (2 novembre 2015) : 29939–71. http://dx.doi.org/10.5194/acpd-15-29939-2015.

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Abstract. The representation of vertical velocity in chemistry climate models is a key element for the representation of the large scale Brewer–Dobson-Circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Messy Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10 year simulation are provided for both, kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows younger mean age of air in the inner tropical upwelling branch and older mean age in the extratopical tropopause region.
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Hoppe, Charlotte Marinke, Felix Ploeger, Paul Konopka et Rolf Müller. « Kinematic and diabatic vertical velocity climatologies from a chemistry climate model ». Atmospheric Chemistry and Physics 16, no 10 (23 mai 2016) : 6223–39. http://dx.doi.org/10.5194/acp-16-6223-2016.

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Abstract. The representation of vertical velocity in chemistry climate models is a key element for the representation of the large-scale Brewer–Dobson circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10-year simulation are provided for both kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely, upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities and analyze the impact of residual circulation and mixing processes on the age of air. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows a younger mean age of air in the inner tropical upwelling branch and an older mean age in the extratropical tropopause region.
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Thèses sur le sujet "Vertical velocities"

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Barnhart, Gregory J. « Predicting hail size using model vertical velocities ». Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://bosun.nps.edu/uhtbin/hyperion-image.exe/08Mar%5FBarnhart.pdf.

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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2008.
Thesis Advisor(s): Nuss, Wendell. "March 2008." Description based on title screen as viewed on April 25, 2008. Includes bibliographical references (p. 47-49). Also available in print.
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Wayne, Simon Patrick. « A LABORATORY INVESTIGATION OF THE NEAR-SURFACE VELOCITIES IN TORNADO-LIKE VORTICES ». Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1186170043.

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Cortés, Morales Diego. « Large-scale Vertical Velocities in the Global Open Ocean via Linear Vorticity Balance ». Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS061.

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À l'échelle des bassins océaniques, les vitesses verticales présentent des valeurs nettement inférieures à celles des vitesses horizontales, imposant ainsi un défi considérable en ce qui concerne leur mesure directe dans l'océan. Par conséquent, leur évaluation nécessite une combinaison d'ensembles de données observationnelles et de considérations théoriques. Diverses méthodes ont été tentées, allant de celles qui se fondent sur la divergence du courant horizontal in situ à celles qui reposent sur des équations complexes de type oméga. Cependant, l'équilibre de Sverdrup a attiré l'attention des chercheurs, y compris la nôtre, en raison de sa description robuste et simple de la dynamique des océans. L'une de ses composantes fondamentales est l'équilibre de vorticité linéaire (LVB: βv = f ∂z w). Celle-ci introduit une dimension verticale dans l'équilibre de Sverdrup conventionnel, en établissant un lien entre le mouvement vertical et le transport méridien au-dessus de lui. Afin de progresser dans la perspective théorique de l'estimation des vitesses verticales, on analyse la validité de cet équilibre linéaire dans une simulation de modèle de circulation générale océanique (OGCM) eddy-permitting. Au départ, cette analyse est effectuée dans la région de l'océan Atlantique Nord, puis étendue à l'ensemble de l'océan mondial, en mettant l'accent sur des échelles supérieures à des échelles plus grandes que 5 degrés. L'analyse a révélé la faisabilité du calcul d'un champ de vitesse verticale robuste sous la couche de mélange en utilisant l'approche LVB pour de grandes fractions de la colonne d'eau dans les régions intérieures des gyres tropicaux et subtropicaux, ainsi que dans certaines couches de la circulation subpolaire et australe à des échelles de temps annuelles et interannuelles. Des déviations par rapport à la LVB se produisent dans les courants de la frontière occidentale, les flux tropicaux zonaux forts, les gyres subpolaires et les échelles plus petites en raison des non-linéarités, des mélanges et des contributions au bilan de vorticité induites par la bathymétrie. L'étude de la validité de la LVB dans l'océan global fournit une base relativement simple pour l'estimation des vitesses verticales à travers de la LVB intégrée indéfinie en profondeur. Grâce à l'utilisation d'un OGCM, il a été démontré que ces estimations ont la capacité de reproduire avec précision l'amplitude temporelle moyenne et de la variabilité interannuelle des vitesses verticales dans des portions substantielles de l'océan global, en comparaison avec le modèle de référence. Nous construisons ici le produit DIOLIVE (Depth-Indefinitive integrated Observation-based LInear Vorticity Estimates) dérivé des vitesses géostrophiques ARMOR3D basées sur des observations et appliquées à la LVB intégrée indéfinie en profondeur, avec les données de forçage du vent ERA5 comme conditions limites à la surface. Ce produit contient des vitesses verticales couvrant l'ensemble de la thermocline globale à une résolution horizontale de 5 degrés et 40 niveaux isopycnaux pendant la période 1993-2018.Une analyse comparative entre le produit DIOLIVE et quatre autres produits de vitesse verticale, comprenant une simulation OGCM, deux réanalyses et une reconstruction basée sur l'observation de l'équation oméga, est proposée. Diverses métriques sont utilisées pour évaluer les caractéristiques multidimensionnelles de la circulation verticale de l'océan. Le produit basé sur l'équation oméga révèle d'importantes divergences par rapport à la synchronisation et à la baroclinicité reproduites par l'ensemble de validation. Mais, dans les régions où la LVB est une hypothèse valide, le produit DIOLIVE démontre une capacité remarquable à reproduire la structure barocline de l'océan, présentant une cohérence spatiale satisfaisante et un accord notable en termes de variabilité temporelle lorsqu'il est comparé aux deux réanalyses et à la simulation OGCM
At oceanic basin scales, vertical velocities are several orders of magnitude smaller than their horizontal counterparts, rendering a formidable challenge for their direct measurement in the real ocean. Therefore, their estimations need a combination of observation-based datasets and theoretical considerations.Historically, scientists have employed various techniques to estimate vertical velocities across different scales constrained by the available observations of their time. Various approaches have been attempted, ranging from methods utilizing in situ horizontal current divergence to those based on intricate omega-type equations. However, the Sverdrup balance has captured the attention of researchers and ours due to its robust and straightforward description of ocean dynamics. One of the fundamental components of the Sverdrup balance is the linear vorticity balance (LVB: βv = f ∂z w). It introduces a novel vertical dimension to the conventional Sverdrup balance, establishing a connection between vertical movement and the meridional transport above it.In order to advance on the theoretical prospect of estimating the vertical velocities, it is primarily identified the annual and interannual timescales patterns governing the linear vorticity balance within an eddy-permitting OGCM simulation. Initially, this analysis is conducted over the North Atlantic Ocean, and subsequently expanded to encompass the entire global ocean, focusing on larger scales than 5 degrees. The analysis revealed the feasibility of computing a robust vertical velocity field beneath the mixed layer using the LVB approach across large fractions of the water column in the interior regions of tropical and subtropical gyres and within some layers of the subpolar and austral circulation. Departures from the LVB occur in the western boundary currents, strong zonal tropical flows, subpolar gyres and smaller scales due to the nonlinearities, mixing and bathymetry-driven contributions to the vorticity budget.The extensive validity of the LVB description of the global ocean provides a relatively simple foundation for estimating the vertical velocities through the indefinite depth-integrated LVB. Using an OGCM, it has demonstrated that the estimates possess the capability to accurately reproduce the time-mean amplitude and interannual variability of the vertical velocity field within substantial portions of the global ocean when compared to the reference model. Here, we build the DIOLIVE (indefinite Depth-Integrated Observation-based LInear Vorticity Estimates) product by applying the observation-based geostrophic velocities from ARMOR3D into the indefinite depth-integrated LVB formalism, with wind stress data from ERA5 serving as boundary condition at the surface. This product contains vertical velocities spanning the global ocean's thermocline at 5 degrees horizontal resolution and 40 isopycnal levels during the 1993-2018 period.A comparative analysis between the DIOLIVE product and four alternative products, including one OGCM simulation, two reanalyses and an observation-based reconstruction based on the omega equation, is conducted using various metrics assessing the vertical circulation's multidimensional features of the ocean vertical flow. The omega equation-based product displays large departures from the synchronicity and baroclinicity reproduced by the validation ensemble. However, in regions where the LVB holds as a valid assumption, the DIOLIVE product demonstrates a remarkable ability to replicate the baroclinic structure of the ocean, exhibiting satisfactory spatial consistency and notable agreement in terms of temporal variability when compared to the two reanalyses and the OGCM simulation
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Farthing, Daniel Gerald. « The relationship between vertical jumping ability and lower extremity strength measured eccentrically and concentrically at five angular velocities ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0013/MQ39138.pdf.

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Vachalek, Roger E. « Case studies of divergence and vertical velocities calculated using different sensing systems ». 1987. http://catalog.hathitrust.org/api/volumes/oclc/17542682.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1987.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 173-176).
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Creasey, Robert L. « A comparison of horizontal and vertical velocities obtained from the flatland ST wind profiler and nested grid model analyses ». 1991. http://catalog.hathitrust.org/api/volumes/oclc/24334337.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1991.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 68-70).
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Lloyd, Michelle. « Patterns in the larval vertical distribution of marine benthic invertebrates in a shallow coastal embayment ». 2011. http://hdl.handle.net/10222/14288.

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Processes during the meroplanktonic phase regulate population dynamics for many marine benthic invertebrates. I examined changes in vertical distribution of different meroplanktonic larvae in a coastal embayment during a stable period, at high temporal frequencies and spatial resolutions. Plankton samples were collected at 6 depths (3, 6, 9, 12, 18, 24 m) using a pump, every 2-h over a 36- and a 25-h period, during a spring and neap tide, respectively, concurrently with measures of temperature, salinity, fluorescence and current velocity. For 10 gastropod taxa, larval vertical distribution was mostly related to the thermal structure of the water column. Each of 7 taxonomic groups was found either exclusively near the surface, associated with the fluorescence maximum, or showed diel changes in distribution. These larvae that occupy different depths in the water column exhibit different dispersal potentials.
Biogeographical data contained in this thesis will be submitted to the Oceanographic Biogeographic Information System (OBIS) and may be accessed on-line at http://www.iobis.org
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Chu, Chen-Yeon, et 朱正永. « Effect of Particle Size Distribution of a Single Verticl Nozzle with High Velocities in a Fluidized Bed ». Thesis, 1997. http://ndltd.ncl.edu.tw/handle/49289853886210734089.

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碩士
逢甲大學
化學工程研究所
85
Abstract Within the processes of fluidized bed combustor and catalyst regenerator, there are recycling part of fly ash and reintroducing into the bed of reactor to improve the efficiency, or being feedback the used catalyst into the bubbling fluidized bed for regeneration. In the feedback processes, the over high velocities in the feedback tube will significantly cause attrition in the bed and result into the elutriation of fine particle, also change the particle size distribution and hydrodynamics of the bed. Experimental work was carried out in a batch gas fluidized bed with 6.62cm inner diameter and 2.5m height and perforated distributor. Operating velocities is controlled between from 1 to 5 Umf (minimum fluidization velocity), and the single nozzle gas velocities are handled from 50m/s to 208m/s with inner diameters of 3,4,4.5, and 5mm individually. The used materials are silica sand that are the average sieve diameters of 195,296, and 421mm respectively. The experimental results show that the attrition is function of particle size distribution, materials nature, single nozzle velocities and superficial gas velocities, the empirical attrition rates have been developed by two models; one is from the energy (model 1), the other is from particle motion (model 2). There are shown as follows: Model 1：Rt=ka0Fr*= ka0(Uor+Us)(U0-Umf)W/(gdp) ka0=7.943×10-10 [1/s] for sand Model 2：Rt=ka0(Uor+Us)(QB/A)W where (QB/A)=r(U0-Umf) ka0=2.597×10-7[s/m2 ] for sand The elutriation rate constant is modified by attrition effect. We define the attrition elutriation constant, Kia*, instead of Ki* for the elutriation dominated by attrition effect. We also modify Geldart (1979) empirical correlation, and develop the empirical elutriation equation as follows for this attrition elutriation system: Kia*/pgU0=7.5 exp[-5.4Ut/U0] for U0＞Ut
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Livres sur le sujet "Vertical velocities"

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Estimating Equatorial F-Region Daytime Vertical E x B Drift Velocities from Ground-Based Magnetometer Measurements in the Philippine Longitude Sector. Storming Media, 2004.

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Chapitres de livres sur le sujet "Vertical velocities"

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Galperin, E. I. « Certain Aspects of the Determination of Velocities from VSP Data ». Dans Vertical Seismic Profiling and Its Exploration Potential, 259–79. Dordrecht : Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5195-2_9.

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Cantoni, Irene, Arne Van Der Hout, Erik Jan Houwing, Alfred Roubos et Michel Ruijter. « Field Measurements of Flow Velocities in Propeller Jets ». Dans Lecture Notes in Civil Engineering, 82–100. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6138-0_8.

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AbstractPropellers of ships generate high velocities adjacent to quay walls, jetties and locks. Generally, a bottom protection is installed in order to prevent instability due to scour. Although design guidance exist, propeller-induced loads are far from fully understood and have predominantly been derived on the basis of model tests. The validation of the existing design methods is lacking, especially for specific types of bow thrusters. In this research, field measurements of flow velocities induced by a 4-channel bow thruster system against a vertical quay wall have been performed. Test results showed a flow characterized by low mean velocities and large fluctuations, with the extent of reflected flow limited to few meters from the quay wall and inflow beneath the suction points playing a role.
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Lynch, Nancy J., et Robert S. Cherry. « Design of Passively Aerated Compost Piles : Vertical Air Velocities between the Pipes ». Dans The Science of Composting, 973–82. Dordrecht : Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1569-5_93.

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Anderson, David. « Daytime Vertical E×B Drift Velocities Inferred from Ground-Based Equatorial Magnetometer Observations ». Dans Aeronomy of the Earth's Atmosphere and Ionosphere, 203–10. Dordrecht : Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0326-1_14.

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Jamet, Quentin, Etienne Mémin, Franck Dumas, Long Li et Pierre Garreau. « Toward a Stochastic Parameterization for Oceanic Deep Convection ». Dans Mathematics of Planet Earth, 143–57. Cham : Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-40094-0_6.

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AbstractCurrent climate models are known to systematically overestimate the rate of deep water formation at high latitudes in response to too deep and too frequent deep convection events. We propose in this study to investigate a misrepresentation of deep convection in Hydrostatic Primitive Equation (HPE) ocean and climate models due to the lack of constraints on vertical dynamics. We discuss the potential of the Location Uncertainty (LU) stochastic representation of geophysical flow dynamics to help in the process of re-introducing some degree of non-hydrostatic physics in HPE models through a pressure correction method. We then test our ideas with idealized Large Eddy Simulations (LES) of buoyancy driven free convection with the CROCO modeling platform. Preliminary results at LES resolution exhibit a solution obtained with our Quasi-nonhydrostatic (Q-NH) model that tends toward the reference non-hydrostatic (NH) model. As compared to a pure hydrostatic setting, our Q-NH solution exhibits vertical convective plumes with larger horizontal structure, a better spatial organization and a reduced intensity of their associated vertical velocities. The simulated Mixed Layer Depth (MLD) deepening rate is however too slow in our Q-NH experiment as compared to the reference NH, a behaviour that opposes to that of hydrostatic experiments of producing too fast MLD deepening rate. These preliminary results are encouraging, and support future efforts in the direction of enriching coarse resolution, hydrostatic ocean and climate models with a stochastic representation of non-hydrostatic physics.
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Anderson, David, et Tzu-Wei Fang. « Determining the Longitude Dependence of VerticalE × BDrift Velocities Associated with the Four-Cell, Nonmigrating Tidal Structure ». Dans Ionospheric Space Weather, 93–104. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781118929216.ch8.

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Lock, G. S. H. « Introduction ». Dans The Tubular Thermosyphon, 1–34. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198562474.003.0001.

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Abstract At any given moment, huge amounts of thermal energy leave the earth’s surface to be carried upwards by natural convection. In this process, energy is transported by bulk motion of the fluid within which it is temporarily stored. Typically, the process is much more effective than thermal conduction which relies on diffusive molecular interactions. The latter take place at molecular velocities which hover around the velocity of sound; but molecular motion is omnidirectional and thus creates no net energy flux in any particular direction unless the temperature, and hence the sonic velocity, varies in that direction. Convective velocities, on the other hand, are frequently much less than the sonic velocity but arise in circumstances where they are essentially unidirectional; moreover, they are capable of producing large vertical energy fluxes in the presence of small vertical temperature gradients. This distinction between the microscopic and macroscopic manifestations of molecular energy flux is at the root of many natural phenomena observed in the atmosphere, the oceans, and the core of the earth.
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« Advances in Fisheries Bioengineering ». Dans Advances in Fisheries Bioengineering, sous la direction de David L. Smith, Mark A. Allen et Ernest L. Brannon. American Fisheries Society, 2008. http://dx.doi.org/10.47886/9781934874028.ch4.

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Abstract<em>.</em>—Focal positions of drift-feeding salmonids are often proximate to higher velocities and may be characterized by velocity gradients. Velocity gradients result in distortion of the flow field through linear deformation and angular deformation, which are summarized as the normal and shear strain rates, respectively. The objective of our study was to use a metric termed the exposure strain rate to quantify velocity gradients used by juvenile spring Chinook salmon <em>Oncorhynchus tshawytscha </em>across habitat type, seasons, and spatial scales. Within a habitat type, focal and mean water column velocities were measured at the position of each fish. In addition, mean column velocities were measured 0.6 and 1.2 m laterally toward the center of the channel. Three exposure strain rates were calculated as the difference between focal and mean column velocity in the vertical scale and at 0.6 and 1.2 m lateral scale divided by the length of the smallest fish (0.4 cm) length scale for all seasons and habitat types. This allowed direct comparison of exposure strain rates for all sizes of fish. The data revealed that for Chinook salmon larger than 4 cm, the distribution of vertical exposure strain rates was similar across all habitat types by season. Exposure strain rates began to vary between habitat types for the lateral scale, reflecting hydraulic differences between reach-scale habitat features. We concluded that juvenile Chinook occupied a specific shear environment independent of reach-scale habitat. Exposure strain rates described microhabitat use in a manner reflecting the habitat occupancy model for drift-feeding salmonids. For this reason, exposure strain rates provide more specific information on habitat use than focal velocities alone.
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« Advances in Fisheries Bioengineering ». Dans Advances in Fisheries Bioengineering, sous la direction de David L. Smith, Mark A. Allen et Ernest L. Brannon. American Fisheries Society, 2008. http://dx.doi.org/10.47886/9781934874028.ch4.

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Abstract<em>.</em>—Focal positions of drift-feeding salmonids are often proximate to higher velocities and may be characterized by velocity gradients. Velocity gradients result in distortion of the flow field through linear deformation and angular deformation, which are summarized as the normal and shear strain rates, respectively. The objective of our study was to use a metric termed the exposure strain rate to quantify velocity gradients used by juvenile spring Chinook salmon <em>Oncorhynchus tshawytscha </em>across habitat type, seasons, and spatial scales. Within a habitat type, focal and mean water column velocities were measured at the position of each fish. In addition, mean column velocities were measured 0.6 and 1.2 m laterally toward the center of the channel. Three exposure strain rates were calculated as the difference between focal and mean column velocity in the vertical scale and at 0.6 and 1.2 m lateral scale divided by the length of the smallest fish (0.4 cm) length scale for all seasons and habitat types. This allowed direct comparison of exposure strain rates for all sizes of fish. The data revealed that for Chinook salmon larger than 4 cm, the distribution of vertical exposure strain rates was similar across all habitat types by season. Exposure strain rates began to vary between habitat types for the lateral scale, reflecting hydraulic differences between reach-scale habitat features. We concluded that juvenile Chinook occupied a specific shear environment independent of reach-scale habitat. Exposure strain rates described microhabitat use in a manner reflecting the habitat occupancy model for drift-feeding salmonids. For this reason, exposure strain rates provide more specific information on habitat use than focal velocities alone.
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Xia, Yan. « Study on Vibration Reduction Due to Pile-Raft Foundation for High-Tech Lab Based on Frequency Sweep Test ». Dans Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210297.

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Evaluation of the vibration reduction of piled-slab is of great significance for the layout of process and power equipment in high-tech facilities. In-situ measurement was performed to study the vibration reduction of the piled-slab of a high-tech lab. Slab vibrations with frequencies of 10 Hz to 60 Hz with steps 5 Hz were induced by an electromagnetic vibration exciter. INV3062U data acquisition device and 941B sensor were used to measure the velocities in the vertical direction at six measurement locations on the slab surface. For single frequency, the measurement results showed that the peak values of the slab vibration velocities generally decayed nonlinearly as the distance increased, however, the attenuations of 25 Hz, 35 Hz, 40 Hz, 50 Hz and 60 Hz slab vibrations were not monotonically.
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Actes de conférences sur le sujet "Vertical velocities"

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Fuda, Jean-Luc, Stéphanie Barrillon, Caroline Comby, Andrea Doglioli, Patrice Le Gal et Anne Petrenko. « Estimating ocean vertical velocities using an autonomous multipurpose profiler ». Dans 2023 IEEE International Workshop on Metrology for the Sea ; Learning to Measure Sea Health Parameters (MetroSea). IEEE, 2023. http://dx.doi.org/10.1109/metrosea58055.2023.10317407.

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Cox, Daniel T., Nobuhisa Kobayashi et Akio Okayasu. « Vertical Variations of Fluid Velocities and Shear Stress in Surf Zones ». Dans 24th International Conference on Coastal Engineering. New York, NY : American Society of Civil Engineers, 1995. http://dx.doi.org/10.1061/9780784400890.009.

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Ruiz, Javier, et Gabriel Navarro. « Diagnosing upwelling vertical velocities by combined temperature chlorophyll and remote sensing ». Dans Remote Sensing, sous la direction de Charles R. Bostater, Jr. et Rosalia Santoleri. SPIE, 2004. http://dx.doi.org/10.1117/12.565471.

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Chang, Tae-Hyun, Sang-Cheol Kil, Deog Hee Doh et Sang youn Kim. « Experiments on Swirling Flow in a Vertical Circular Tube ». Dans ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-31010.

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Swirling flows are related to spiral motion in the tangential direction in addition to the axial and radial direction using several swirl generators. These kinds of flows are used for combustion chambers to improve the flame stability, heat exchanger enhancing heat transfer coefficients, agricultural spraying machines and some vertical pipes to move slurries or conveying of materials. But, few papers have dealt with three dimensional velocities profiles in a vertical pipe. In this paper, 3 dimension PIV technique has employed to measure velocities profiles in water along a vertical circular pipe for Re = 3000 ∼ 13,000. The swirl generator to be used is tangential inlet condition to produce the flow. The velocities and flow noise have been measured with swirl in the water and air along the test tube.
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Gottmann, Matthias, Tomomi Oishi, K. R. Sridhar et Ranganathan Kumar. « Interface Shape and Wave Velocities of Air-Water Flows in a Vertical Duct ». Dans ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0753.

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Abstract This paper describes the experimental investigation of an upward annular air-water flow in a duct with a 6.35 mm by 63.5 mm rectangular cross section. The test section was instrumented to study the shape of the interface and the interfacial wave velocity. Flush-wire electrical conductivity probes were used to obtain local film thickness measurement with a spatial resolution of 200 μm or better and a temporal resolution greater than 2 kHz. The probe design and a statistical calibration method are discussed. Two flush-wire probes which allow the determination of wave propagation velocities have been implemented. Pressure drop in the channel was measured to provide a measure of averaged momentum transfer in the channel. A simple model for the prediction of interfacial wave velocities is presented, and it matches the data favorably.
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Caprace, Denis-Gabriel, et Andrew Ning. « Large Eddy Simulation of the Wakes of Three Urban Air Mobility Vehicles ». Dans Vertical Flight Society 78th Annual Forum & Technology Display. The Vertical Flight Society, 2022. http://dx.doi.org/10.4050/f-0078-2022-17471.

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Recent advances in urban air mobility have driven the development of many new VTOL concepts. These vehicles often feature original designs and futuristic shapes. Due to their novelty, the wake characteristics of such aircraft are unknown. However, large wake-induced velocities, should they exist, may be dangerous for any other vehicle evolving in their close proximity. Therefore, improved knowledge about the wakes of VTOL vehicles is needed to guarantee the safety of urban air mobility operations. In this work, we study the wake of three VTOL aircraft in cruise by means of large eddy simulation. We present a two-stage numerical procedure that enables the simulation of long wake ages at a limited computational cost. The analysis of our simulation results reveals that the wakes of rotary vehicles feature larger wake vortex cores than a typical airplane wing. The vortex circulation decay is also faster due to the self-induced turbulence generated during the wake roll-up. Finally, we introduce a model of the vortex circulation distribution that fits the numerical measurements with satisfactory agreement across space and time, and can be used to evaluate induced velocities.
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Caprace, Denis-Gabriel, Patricia Diaz et Seokkwan Yoon. « Simulation of the Rotorwash Induced by a Quadrotor Urban Air Taxi in Ground Effect ». Dans Vertical Flight Society 79th Annual Forum & Technology Display. The Vertical Flight Society, 2023. http://dx.doi.org/10.4050/f-0079-2023-17974.

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A rotorcraft hovering near the ground causes downwash and outwash. The impact of these induced velocities on urban air mobility operations has not been extensively quantified. This paper explores the opportunity of using CFD to perform dedicated studies on the aerodynamics of rotorcraft in ground effect (IGE). For this purpose, we compare load and flow predictions obtained with the high-fidelity CFD solver OVERFLOW and with a medium-fidelity vortex particle-mesh (VPM) method, for a single rotor IGE. We show that the computational cost of high-fidelity simulation makes it impractical to sweep through a large number of configurations or operating conditions. However, a small set of cases can be used to verify a medium-fidelity tool. The latter provides a better trade-off between 'accuracy' and computational intensity, which enables numerous, longer simulations at a more affordable cost. As an example, the outwash flow is computed for two different designs of a quadrotor air taxi in hover and reveals the existence of increased velocities between the rotors. This work illustrates how CFD can help identify dangerous areas for passengers and ground personnel when they approach the vehicle.
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Ejim, Chidirim. « Establishing Critical Gas Velocities for Liquid Loading in Deviated Gas Wells ». Dans Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213620-ms.

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Abstract Severe liquid loading in wells producing from some wet gas reservoirs, results in the well being unable to transport fluids to surface. In field applications, liquid loading is known to be more pronounced in deviated wells than in vertical wells. This study highlights a methodology to estimate the critical velocities for liquid loading in inclined gas wells. Knowledge and use of the technique is of importance to production engineers and stakeholders of a gas asset. Test data from a 3-inch diameter line with inclination from vertical to near horizontal was obtained from open literature. For each deviation angle, and based on the test conditions, a correlation for liquid holdup in inclined wells was used to determine the void fraction at the region of interest. The corresponding maximum and average film thicknesses, as well as the interfacial friction factor were determined. The principle of momentum conservation for a deviated tubing was applied and the superficial critical gas velocities for liquid loading were estimated. These estimated velocities were compared to those obtained from the test data. For the different superficial liquid velocities investigated, the estimated critical gas velocities increased with increasing deviation from vertical. The maximum critical velocity was reached when the deviation angle was about 40° to 50° from vertical. Beyond this point, the critical gas velocity decreased with increasing deviation angle from vertical up to the near-horizontal inclination. The results also showed that the gas critical velocity increased with increasing liquid superficial velocity. The overall trend of the critical velocity variation was similar to the trend in the actual test data obtained from open literature. The range of estimated critical gas velocities varied from about 9 m/s to about 35 m/s, with overall Root Mean Square Errors between 3.3 m/s and 6 m/s. In conclusion, results from this methodology was able to give a first-hand estimate of critical superficial velocities for inclined gas wells. This work presents a methodology to estimate critical gas velocities for inclined gas wells. This knowledge is important for field engineers and asset managers in the planning and production phases of gas wells. The benefits include optimizing the gas completion hardware during design, and maximizing gas flow rates during production operation. Overall, this increases the economic bottom-line for the field operator.
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Jay, D. A., P. Orton, D. J. Kay, A. Fain et A. M. Baptista. « Acoustic determination of sediment concentrations, settling velocities, horizontal transports and vertical fluxes in estuaries ». Dans Proceedings of the IEEE Sixth Working Conference on Current Measurement (Cat. No.99CH36331). IEEE, 1999. http://dx.doi.org/10.1109/ccm.1999.755251.

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Dhir, Professor V. K., P. K. Meduri et G. R. Warrier. « FLOW FILM BOILING ON A VERTICAL FLAT PLATE AT DIFFERENT SUBCOOLINGS AND FLOW VELOCITIES ». Dans Annals of the Assembly for International Heat Transfer Conference 13. Begell House Inc., 2006. http://dx.doi.org/10.1615/ihtc13.p28.10.

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Rapports d'organisations sur le sujet "Vertical velocities"

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Larsen, M. F. Radar Interferometric Studies of Jetstream Vertical Velocities and Precipitating Regions. Fort Belvoir, VA : Defense Technical Information Center, mai 2000. http://dx.doi.org/10.21236/ada380321.

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Larsen, M. F. Radar interferometer Investigations of the Horizontal Winds, Vertical Velocities : EPSCoR Supplement for Student Support. Fort Belvoir, VA : Defense Technical Information Center, février 1997. http://dx.doi.org/10.21236/ada337289.

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Bainer, R. W., J. W. Rector, B. Braile, P. Milligan et J. Selbig. Vertical seismic profiling at Borehole B-1015, Lawrence Livermore National Laboratory : Motivation, data acquisition, data analysis, and formation velocities. Office of Scientific and Technical Information (OSTI), janvier 1997. http://dx.doi.org/10.2172/514894.

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Larsen, M. F. Radar Interferometer Investigations of the Horizontal Winds, Vertical Velocities, Vorticity, and Divergence Around Frontal Zones and in Mesoscale Waves. Fort Belvoir, VA : Defense Technical Information Center, janvier 1996. http://dx.doi.org/10.21236/ada305489.

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Hunter, J. A., H L Crow, B. Dietiker, A. J. M. Pugin, K. Brewer et T. Cartwright. A compilation of microtremor horizontal-to-vertical spectral ratios (HVSRs) and borehole shear-wave velocities of unconsolidated sediments in south-central Ontario. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2020. http://dx.doi.org/10.4095/326133.

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