A new type of boundary layer in a rapidly rotating gas

1983 ◽  
Vol 126 ◽  
pp. 431-442 ◽  
Author(s):  
Takuya Matsuda ◽  
Keizo Nakagawa
Keyword(s):  
Boundary Layer ◽  
Temperature Jump ◽  
Ekman Layer ◽  
Infinite Length ◽  
Gaseous Flow ◽  
Ekman Number ◽  
New Type ◽  
Vertical Walls ◽  
Source Sink

Gaseous flow in a pie-shaped cylinder of infinite length rotating about the apex is considered. The horizontal flow is induced either by the temperature distribution or by the source/sink distribution on the walls θ = constant. It is found that along the vertical walls θ = constant the E½ boundary layer is formed, where E is the Ekman number. Although the equation governing the above boundary layer is very similar to that of the Ekman layer, it is a new type of boundary layer which may be called the buoyancy layer. Along the wall on which r is constant thermal boundary layers very similar to the Stewartson layers are found to be formed. The role of these layers is to mediate the temperature jump. These layers disappear in the incompressible limit.

Numerical study of the motions within a slowly precessing sphere at low Ekman number

2001 ◽  
Vol 437 ◽  
pp. 283-299 ◽  
Author(s):  
JÉRÔME NOIR ◽  
D. JAULT ◽  
P. CARDIN
Keyword(s):  
Boundary Layer ◽  
Shear Layer ◽  
Numerical Study ◽  
Ekman Layer ◽  
Shear Layers ◽  
Nonlinear Interactions ◽  
Geostrophic Velocity ◽  
Ekman Number ◽  
Geostrophic Shear ◽  
Good Agreement

A geostrophic circulation and a pair of oblique oscillating shear layers arise in a spherical uid cavity contained in a slowly precessing rigid body. Both are caused by the breakdown of the Ekman boundary layer at two critical circles. We rely on numerical modelling to characterize these motions for very small Ekman numbers. Both the O(E1/5) amplitude of the velocity in the oscillating shear layer and the width (also O(E1/5)) of these oblique layers are the result of in ux into the interior from the regions where the Ekman layer breaks down. The oscillating motions are confined to narrow shear layers and their amplitude decays exponentially away from the characteristic surfaces. Nonlinear interactions inside the boundary layer drive the geostrophic shear layer attached to the critical circles. This steady layer, again of O(E1/5) thickness, contains O(E−3/10) velocities. Our results are in good agreement with the experimental measurement by Malkus of the geostrophic velocity arising in a slowly precessing spheroid.

An overlooked aspect of the wind-driven oceanic circulation

1968 ◽  
Vol 32 (4) ◽  
pp. 809-821 ◽  
Author(s):  
Joseph Pedlosky
Keyword(s):  
Boundary Layer ◽  
Simple Model ◽  
Mass Flux ◽  
Ekman Layer ◽  
Oceanic Circulation ◽  
Wind Driven Circulation

The wind-driven circulation of a simple model of the oceanic circulation (linear and homogeneous) is investigated in detail to delineate the role of the Ekman layer mass flux in driving hitherto overlooked components of the oceanic circulation.The role of upwelling boundary-layer regions in driving interior geostrophic circulations is discussed in detail. Several interesting circulations hidden in the earlier transport theories are described.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

scholarly journals The Role of Source‐sink Dynamics in the Assessment of Risk to Non‐target Arthropods from the Use of Plant Protection Products

2021 ◽  
Author(s):  
Gavin Lewis ◽  
Axel Dinter ◽  
Charlotte Elston ◽  
Michael Thomas Marx ◽  
Christoph Julian Mayer ◽  
...  
Keyword(s):  
Plant Protection ◽  
Plant Protection Products ◽  
Source Sink

Toward a theory on workplaces for smart workers

Facilities ◽  
2019 ◽  
Vol 38 (3/4) ◽  
pp. 298-315
Author(s):  
Luisa Errichiello ◽  
Tommasina Pianese
Keyword(s):  
Web Sites ◽  
Participant Observation ◽  
Secondary Data ◽  
Primary Data ◽  
Innovative Design ◽  
Content Type ◽  
New Type ◽  
Smart Working ◽  
Research Propositions

Purpose The purpose of this paper is to identify the main features of smart work centers (SWCs) and show how these innovative offices would support the implementation of smart working and related changes in workspaces (“bricks”), technologies (“bytes”) and organizational practices (“behaviors”). Design/methodology/approach In this study, scientific literature is combined with white papers and business reports and visits to 14 workplaces, including offices designed as SWCs, co-working spaces, one telecenter, one accelerator and one fab lab. Primary data were collected through interviews with managers and users and non-participant observation, whereas secondary data included web-sites, brochures, presentations, press releases and official documents. Findings The authors developed research propositions about how the design of spaces and the availability of technology within SWCs would support the “bricks” and “bytes” levers of smart working. More importantly, the authors assumed that this new type of workplace would sustain changes in employees’ behaviors and managers’ practices, thus helping to overcome several challenges traditionally associated with remote working. Research limitations/implications The exploratory nature of the research only provides preliminary information about the role of SWCs within smart working programs. Additional qualitative and quantitative empirical investigation is required. Practical implications This study provides valuable knowledge about how the design of corporate offices can be leveraged to sustain the implementation of smart working. Originality/value This study advances knowledge on workplaces by focusing on an innovative design of traditional offices (SWC). It also lays the foundations for future investigation aimed at testing the developed propositions.

The Entrepreneurial University: Evidence of the Changing Role of Universities in Modern Russia

2014 ◽  
Vol 28 (4) ◽  
pp. 271-280 ◽  
Author(s):  
Dina Williams ◽  
Alexey Kluev
Keyword(s):  
Entrepreneurial University ◽  
Primary Data ◽  
Strategy Development ◽  
Infrastructure Development ◽  
Innovation Development ◽  
Policy Makers ◽  
Managerial Competencies ◽  
New Type ◽  
Changing Role

This paper examines the evolution of the entrepreneurial function of Russia's leading universities: the study is based on a conceptualization of a university's entrepreneurial development pathway developed by the OECD in 2009. The data on entrepreneurship development were collected in 2012 through a survey of technology transfer and innovation development managers of 18 National Research Universities. The primary data were complemented by desktop analysis of the strategy development documents of the universities surveyed. The results suggest that in the period studied, 2008–2012, a new type of university, the entrepreneurial university, has emerged in Russia. However, these entrepreneurial universities are facing serious challenges in the implementation of an entrepreneurial, innovation-oriented mission due to the lack of managerial competencies and inadequate infrastructure development. The paper has significant theoretical and practical implications in shedding light on the development of the entrepreneurial university in Russia, where the process is still in its infancy. The authors depict a trajectory of entrepreneurial transformation in and barriers to this process that, it is argued, university executives and policy makers should take into consideration.

scholarly journals Heat transfer in rotating Rayleigh–Bénard convection with rough plates

2017 ◽  
Vol 830 ◽  
Author(s):  
Pranav Joshi ◽  
Hadi Rajaei ◽  
Rudie P. J. Kunnen ◽  
Herman J. H. Clercx
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Ekman Layer ◽  
Ekman Pumping ◽  
Ekman Boundary Layer ◽  
Bénard Convection ◽  
Roughness Elements ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

This experimental study focuses on the effect of horizontal boundaries with pyramid-shaped roughness elements on the heat transfer in rotating Rayleigh–Bénard convection. It is shown that the Ekman pumping mechanism, which is responsible for the heat transfer enhancement under rotation in the case of smooth top and bottom surfaces, is unaffected by the roughness as long as the Ekman layer thickness $\unicode[STIX]{x1D6FF}_{E}$ is significantly larger than the roughness height $k$. As the rotation rate increases, and thus $\unicode[STIX]{x1D6FF}_{E}$ decreases, the roughness elements penetrate the radially inward flow in the interior of the Ekman boundary layer that feeds the columnar Ekman vortices. This perturbation generates additional thermal disturbances which are found to increase the heat transfer efficiency even further. However, when $\unicode[STIX]{x1D6FF}_{E}\approx k$, the Ekman boundary layer is strongly perturbed by the roughness elements and the Ekman pumping mechanism is suppressed. The results suggest that the Ekman pumping is re-established for $\unicode[STIX]{x1D6FF}_{E}\ll k$ as the faces of the pyramidal roughness elements then act locally as a sloping boundary on which an Ekman layer can be formed.

Sign in / Sign up

Export Citation Format

Share Document