Modeling of the Mist Dynamics and Heat Transfer at Various Ambient Pressures

A Numerical Model for the Mist Dynamics and Heat Transfer at Various Ambient Pressures

Journal of Fluids Engineering ◽

10.1115/1.1976743 ◽

2005 ◽

Vol 127 (4) ◽

pp. 631-639 ◽

Cited By ~ 8

Author(s):

Roy J. Issa ◽

S. C. Yao

Keyword(s):

Heat Transfer ◽

Numerical Model ◽

Test Data ◽

Model Simulation ◽

Droplet Size Distribution ◽

Atmospheric Conditions ◽

Single Stream ◽

Wide Range ◽

Wall Interaction ◽

Uniform Droplets

A numerical model is developed to simulate the dynamics of the droplet-wall interaction and heat transfer mechanisms at sub-atmospheric to elevated ambient pressures, and for surface temperatures ranging from nucleate to film boiling. This is the first time a general model is developed to study these phenomena over a wide range of ambient pressures. The model provides insight to the optimal flow conditions, and droplet size distribution for best heat transfer enhancement. Simulations are provided for single stream droplet impactions, and for full conical sprays using nozzles that dispense a spectrum of non-uniform droplets. The model simulation was compared against available test data for single stream of droplets at non-atmospheric conditions, and the simulation compared favorably well with the test data.

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On the multi-fractal scaling properties of sea ice deformation

10.5194/tc-2018-290 ◽

2019 ◽

Cited By ~ 1

Author(s):

Pierre Rampal ◽

Véronique Dansereau ◽

Einar Olason ◽

Sylvain Bouillon ◽

Timothy Williams ◽

...

Keyword(s):

Sea Ice ◽

Initial Conditions ◽

Model Simulation ◽

Winter Season ◽

Scaling Properties ◽

Scaling Invariance ◽

Invariance Properties ◽

Wide Range ◽

Set Up ◽

First Time

Abstract. In this paper, we evaluate the neXtSIM sea ice model with respect to the observed scaling invariance properties of sea ice deformation in the spatial and temporal domains. Using an Arctic set-up with realistic initial conditions, state-of-the-art atmospheric reanalysis forcing and geostrophic currents retrieved from satellite data, we show that the model is able to reproduce the observed properties of these scaling in both the spatial and temporal do- mains over a wide range of scales and, for the first time, their multi-fractality. The variability of these properties during the winter season are also captured by the model. We also show that the simulated scaling exhibit a space-time coupling, a suggested property of brittle deformation at geophysical scales. The ability to reproduce the multi-fractality of these scaling is crucial in the context of downscaling model simulation outputs to infer sea ice variables at the sub-grid scale, and also has implication in modeling the statistical properties of deformation-related quantities such as lead fractions, and heat and salt fluxes.

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A numerical and experimental investigation of stability of natural convective flows within a horizontal annulus

Journal of Fluid Mechanics ◽

10.1017/s0022112098002948 ◽

1999 ◽

Vol 381 ◽

pp. 27-61 ◽

Cited By ~ 42

Author(s):

MARK P. DYKO ◽

KAMBIZ VAFAI ◽

A. KADER MOJTABI

Keyword(s):

Heat Transfer ◽

Rayleigh Number ◽

Prandtl Number ◽

Three Dimensional ◽

Flow Stability ◽

Secondary Flows ◽

Flow Structures ◽

Wide Range ◽

First Time ◽

Rayleigh Numbers

A numerical and experimental study of buoyancy-driven flow in the annulus between two horizontal coaxial cylinders at Rayleigh numbers approaching and exceeding the critical values is presented. The stability of the flow is investigated using linear theory and the energy method. Theoretical predictions of the critical Rayleigh number for onset of secondary flows are obtained for a wide range of radius ratio R and are verified by comparison with results of previous experimental studies. A subcritical Rayleigh number which provides a necessary condition for global flow stability is also determined. The three-dimensional transient equations of fluid flow and heat transfer are solved to study the manifestation of instabilities within annuli having impermeable endwalls, which are encountered in various applications. For the first time, a thorough examination of the development of spiral vortex secondary flow within a moderate gap annulus and its interaction with the primary flow is performed for air. Simulations are conducted to investigate factors influencing the size and number of post-transitional vortex cells. The evolution of stable three-dimensional flow and temperature fields with increasing Rayleigh number in a large gap annulus is also studied. The distinct flow structures which coexist in the large gap annulus at high Rayleigh numbers preceding transition to oscillatory flow, including transverse vortices at the end walls which have not been previously identified, are established numerically and experimentally. The solutions for the large-gap annulus are compared to those for the moderate-gap case to clarify fundamental differences in behaviour. Heat transfer results in the form of local Nusselt number distributions are presented for both the moderate- and large-gap cases. Results from a series of experiments performed with air to obtain data for validation of the numerical scheme and further information on the flow stability are presented. Additionally, the change from a crescent-shaped flow pattern to a unicellular pattern with centre of rotation at the top of the annulus is investigated numerically and experimentally for a Prandtl number of 100. Excellent agreement between the numerical and experimental results is shown for both Prandtl numbers studied. The present work provides, for the first time, quantitative three-dimensional descriptions of spiral convection within a moderate-gap annulus containing air, flow structures preceding oscillation in a large-gap annulus for air, and unicellular flow development in a large-gap annulus for large Prandtl number fluids.

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Three-dimensional natural convective states in a narrow-gap horizontal annulus

Journal of Fluid Mechanics ◽

10.1017/s0022112001005067 ◽

2001 ◽

Vol 445 ◽

pp. 1-36 ◽

Cited By ~ 22

Author(s):

MARK P. DYKO ◽

KAMBIZ VAFAI

Keyword(s):

Heat Transfer ◽

Fluid Motion ◽

Three Dimensional ◽

Narrow Gap ◽

Nusselt Numbers ◽

Numerical Studies ◽

Wide Range ◽

Horizontal Cylinders ◽

First Time ◽

Rayleigh Numbers

Buoyancy-driven flow in a narrow-gap annulus formed by two concentric horizontal cylinders is investigated numerically. The three-dimensional transient equations of fluid motion and heat transfer are solved to study multiple supercritical states occurring within annuli having impermeable endwalls, which are encountered in various applications. For the first time, three-dimensional supercritical states are shown to occur in a narrow-gap annulus and the existence of four such states is established. These four states are characterized by the orientations and directions of rotation of counter-rotating rolls that form in the upper part of the annulus owing to thermal instability, and exhibit (i) transverse rolls, (ii) transverse rolls with reversed directions of rotation, (iii) longitudinal rolls in combination with transverse rolls, and (iv) longitudinal rolls with reversed directions of rotation in combination with transverse rolls, respectively. Simulations are performed at Rayleigh numbers approaching and exceeding the critical value to gain insight into the physical processes influencing development of the secondary flow structures. The evolution of the supercritical flow fields and temperature distributions with increasing Rayleigh number and the interaction between the secondary and primary flows are thoroughly investigated. Factors influencing the number of rolls are studied for each supercritical state. Heat transfer results are presented in the form of local Nusselt number distributions and overall annulus Nusselt numbers. Two-dimensional natural convection occurring early in the transient evolution of the flow field is also examined. Results obtained for a wide range of annulus radius ratios and Rayleigh numbers are shown to be in excellent agreement with results from previous experimental and numerical studies, thereby validating the present numerical scheme.

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Safety assessment of biological raw materials in the system of medicines quality assurance

10.33920/med-06-2002-05 ◽

2020 ◽

pp. 63-72

Author(s):

Yu. Olefir ◽

E. Sakanyan ◽

I. Osipova ◽

V. Dobrynin ◽

M. Smirnova ◽

...

Keyword(s):

Raw Materials ◽

State Level ◽

The State ◽

Spongiform Encephalopathy ◽

Safety Standards ◽

Wide Range ◽

The Russian Federation ◽

Key Aspects ◽

First Time ◽

Medicines Quality

The entry of a wide range of biotechnological products into the pharmaceutical market calls for rein-forcement of the quality, efficacy and safety standards at the state level. The following general monographs have been elaborated for the first time to be included into the State Pharmacopoeia of the Russian Federation, XIV edition: "Viral safety" and "Reduction of the risk of transmitting animal spongiform encephalopathy via medicinal products". These general monographs were elaborated taking into account the requirements of foreign pharmacopoeias and the WHO recommendations. The present paper summarises the key aspects of the monographs.

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Innovation in Byzantine Medicine

10.1093/oso/9780198850687.001.0001 ◽

2020 ◽

Author(s):

Petros Bouras-Vallianatos

Keyword(s):

Human Physiology ◽

Medical Literature ◽

Cultural Exchange ◽

Significant Degree ◽

Medieval Medicine ◽

Medieval Latin ◽

Main Thesis ◽

Wide Range ◽

Comprehensive Examination ◽

First Time

Byzantine medicine is still a little-known and misrepresented field not only in the wider arena of debates on medieval medicine but also among Byzantinists. Byzantine medical literature is often viewed as ‘stagnant’ and mainly preserving ancient ideas; and our knowledge of it continues to be based to a great extent on the comments of earlier authorities, which are often repeated uncritically. This book presents the first comprehensive examination of the medical corpus of, arguably, the most important late Byzantine physician John Zacharias Aktouarios (c.1275–c.1330). The main thesis is that John’s medical works show an astonishing degree of openness to knowledge from outside Byzantium combined with a significant degree of originality, in particular, in the fields of uroscopy, pharmacology, and human physiology. The analysis of John’s edited (On Urines and On Psychic Pneuma) and unedited (Medical Epitome) works is supported for the first time by the consultation of a large number of manuscripts. The study is also informed by evidence from a wide range of medical sources, including previously unpublished ones, and texts from other genres, such as epistolography and merchants’ accounts. The contextualization of John’s works sheds new light on the development of Byzantine medical thought and practice, and enhances our understanding of the late Byzantine social and intellectual landscape. Finally, John’s medical observations are also examined in the light of examples from the medieval Latin and Islamic worlds, placing his medical theories in the wider Mediterranean milieu and highlighting the cultural exchange between Byzantium and its neighbours.

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Rebels, Believers, Survivors

10.1093/oso/9780198857297.001.0001 ◽

2020 ◽

Author(s):

Noel Malcolm

Keyword(s):

Catholic Church ◽

Religious Conversion ◽

Late Nineteenth Century ◽

Napoleonic Wars ◽

Conversion To Islam ◽

Wide Range ◽

History Of ◽

External Powers ◽

First Time ◽

Modern Myth

This book of essays covers a wide range of topics in the history of Albania and Kosovo. Many of the essays illuminate connections between the Albanian lands and external powers and interests, whether political, military, diplomatic or religious. Such topics include the Habsburg invasion of Kosovo in 1689, the manoeuvrings of Britain and France towards the Albanian lands during the Napoleonic Wars, the British interest in those lands in the late nineteenth century, and the Balkan War of 1912. On the religious side, essays examine ‘crypto-Christianity’ in Kosovo during the Ottoman period, the stories of conversion to Islam revealed by Inquisition records, the first theological treatise written in Albanian (1685), and the work of the ‘Apostolic Delegate’ who reformed the Catholic Church in early twentieth-century Albania. Some essays bring to life ordinary individuals hitherto unknown to history: women hauled before the Inquisition, for example, or the author of the first Albanian autobiography. The longest essay, on Ali Pasha, tells for the first time the full story of the role he played in the international politics of the Napoleonic Wars. Some of these studies have been printed before (several in hard-to-find publications, and one only in Albanian), but the greater part of this book appears here for the first time. This is not only a contribution to Albanian and Balkan history it also engages with many broader issues, including religious conversion, methods of enslavement within the Ottoman Empire, and the nature of modern myth-making about national identity.

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Recycling and Reuse in the Roman Economy

10.1093/oso/9780198860846.001.0001 ◽

2020 ◽

Keyword(s):

Building Materials ◽

Computational Modelling ◽

Late Antique ◽

Roman Economy ◽

Wide Range ◽

The Status ◽

Recent Developments ◽

Methodological Approaches ◽

First Time ◽

Site Types

The recycling and reuse of materials and objects were extensive in the past, but have rarely been embedded into models of the economy; even more rarely has any attempt been made to assess the scale of these practices. Recent developments, including the use of large datasets, computational modelling, and high-resolution analytical chemistry, are increasingly offering the means to reconstruct recycling and reuse, and even to approach the thorny matter of quantification. Growing scholarly interest in the topic has also led to an increasing recognition of these practices from those employing more traditional methodological approaches, which are sometimes coupled with innovative archaeological theory. Thanks to these efforts, it has been possible for the first time in this volume to draw together archaeological case studies on the recycling and reuse of a wide range of materials, from papyri and textiles, to amphorae, metals and glass, building materials and statuary. Recycling and reuse occur at a range of site types, and often in contexts which cross-cut material categories, or move from one object category to another. The volume focuses principally on the Roman Imperial and late antique world, over a broad geographical span ranging from Britain to North Africa and the East Mediterranean. Last, but not least, the volume is unique in focusing upon these activities as a part of the status quo, and not just as a response to crisis.

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A Virtual Telescope for the Open University Science Foundation Course

International Astronomical Union Colloquium ◽

10.1017/s0252921100114885 ◽

1998 ◽

Vol 162 ◽

pp. 100-105

Author(s):

Andrew J. Norton ◽

Mark H. Jones

Keyword(s):

Social Science ◽

Open University ◽

Distance Teaching ◽

The Arts ◽

Wide Range ◽

University Science ◽

First Time ◽

Degree Level ◽

Selection Of

The Open University is the UK's foremost distance teaching university. For over twenty five years we have been presenting courses to students spanning a wide range of degree level and vocational subjects. Since we have no pre-requisites for entry, a major component of our course profile is a selection of foundation courses comprising one each in the Arts, Social Science, Mathematics, Technology and Science faculties. The Science Faculty's foundation course is currently undergoing a substantial revision. The new course, entitled “S103: Discovering Science”, will be presented to students for the first time in 1998.

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Autophagy Deficiency by Atg4B Loss Leads to Metabolomic Alterations in Mice

Metabolites ◽

10.3390/metabo11080481 ◽

2021 ◽

Vol 11 (8) ◽

pp. 481

Author(s):

Gemma G. Martínez-García ◽

Raúl F. Pérez ◽

Álvaro F. Fernández ◽

Sylvere Durand ◽

Guido Kroemer ◽

...

Keyword(s):

Skeletal Muscle ◽

Amino Acids ◽

Mammalian Cells ◽

Tissue Homeostasis ◽

In Vivo Studies ◽

Protective Mechanism ◽

Cardiac Damage ◽

Wide Range ◽

First Time

Autophagy is an essential protective mechanism that allows mammalian cells to cope with a variety of stressors and contributes to maintaining cellular and tissue homeostasis. Due to these crucial roles and also to the fact that autophagy malfunction has been described in a wide range of pathologies, an increasing number of in vivo studies involving animal models targeting autophagy genes have been developed. In mammals, total autophagy inactivation is lethal, and constitutive knockout models lacking effectors of this route are not viable, which has hindered so far the analysis of the consequences of a systemic autophagy decline. Here, we take advantage of atg4b−/− mice, an autophagy-deficient model with only partial disruption of the process, to assess the effects of systemic reduction of autophagy on the metabolome. We describe for the first time the metabolic footprint of systemic autophagy decline, showing that impaired autophagy results in highly tissue-dependent alterations that are more accentuated in the skeletal muscle and plasma. These changes, which include changes in the levels of amino-acids, lipids, or nucleosides, sometimes resemble those that are frequently described in conditions like aging, obesity, or cardiac damage. We also discuss different hypotheses on how impaired autophagy may affect the metabolism of several tissues in mammals.

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