Comments on “Second-order turbulence closure models for geophysical boundary layers: A review of recent work”

2006 ◽  
Vol 26 (6) ◽  
pp. 819-822 ◽  
Author(s):  
Lakshmi Kantha
Keyword(s):  
Recent Work ◽  
Boundary Layers ◽  
Second Order ◽  
Turbulence Closure ◽  
Closure Models

A critique of some recent second-order turbulence closure models forcompressible boundary layers

1977 ◽  
Author(s):  
M. RUBESIN ◽  
A. CRISALLI ◽  
C. HORSTMAN ◽  
M. ACHARYA ◽  
M. LANFRANCO
Keyword(s):  
Boundary Layers ◽  
Second Order ◽  
Turbulence Closure ◽  
Closure Models

Critical Examination of Two-Equation Turbulence Closure Models for Boundary Layers

AIAA Journal ◽  
1977 ◽  
Vol 15 (6) ◽  
pp. 821-828 ◽  
Author(s):  
Thomas L. Chambers ◽  
David C. Wilcox
Keyword(s):  
Boundary Layers ◽  
Turbulence Closure ◽  
Critical Examination ◽  
Closure Models

Autonomie, Charakter und praktische Vernunft: Überlegungen am Beispiel des Utilitarismus

1999 ◽  
Vol 21 (2) ◽  
Author(s):  
R. Jay Wallace
Keyword(s):  
Recent Work ◽  
Moral Agent ◽  
Second Order ◽  
Bernard Williams ◽  
Personal Projects ◽  
Peter Railton ◽  
Order Reflection

AbstractThis paper explores the question whether utilitarianism is compatible with the autonomy of the moral agent. The paper begins by considering Bernard Williams' famous complaint that utilitarianism cannot do justice to the personal projects and commitments constitutive of character. Recent work (by Peter Railton among others) has established that a utilitarian agent need not be free of such personal projects and commitments, and could even affirm them morally at the level of second"order reflection. But a different and more subtle problem confronts this approach: the use of utilitarian principles to justify the cultivation of personal projects and attachments undermines the autonomy to support this objection, according to which autonomy is a matter of acting in a way one can reflectively endorse.

Mass transfer dominated by thermal diffusion in laminar boundary layers

1997 ◽  
Vol 336 ◽  
pp. 379-409 ◽  
Author(s):  
PEDRO L. GARCÍA-YBARRA ◽  
JOSE L. CASTILLO
Keyword(s):  
Mass Transport ◽  
Boundary Layers ◽  
Thermal Diffusion ◽  
Mass Fraction ◽  
Soret Effect ◽  
Second Order ◽  
Brownian Diffusion ◽  
Diffusion Transport ◽  
Laminar Boundary Layers ◽  
Fraction Distribution

The concentration distribution of massive dilute species (e.g. aerosols, heavy vapours, etc.) carried in a gas stream in non-isothermal boundary layers is studied in the large-Schmidt-number limit, Sc[Gt ]1, including the cross-mass-transport by thermal diffusion (Ludwig–Soret effect). In self-similar laminar boundary layers, the mass fraction distribution of the dilute species is governed by a second-order ordinary differential equation whose solution becomes a singular perturbation problem when Sc[Gt ]1. Depending on the sign of the temperature gradient, the solutions exhibit different qualitative behaviour. First, when the thermal diffusion transport is directed toward the wall, the boundary layer can be divided into two separated regions: an outer region characterized by the cooperation of advection and thermal diffusion and an inner region in the vicinity of the wall, where Brownian diffusion accommodates the mass fraction to the value required by the boundary condition at the wall. Secondly, when the thermal diffusion transport is directed away from the wall, thus competing with the advective transport, both effects balance each other at some intermediate value of the similarity variable and a thin intermediate diffusive layer separating two outer regions should be considered around this location. The character of the outer solutions changes sharply across this thin layer, which corresponds to a second-order regular turning point of the differential mass transport equation. In the outer zone from the inner layer down to the wall, exponentially small terms must be considered to account for the diffusive leakage of the massive species. In the inner zone, the equation is solved in terms of the Whittaker function and the whole mass fraction distribution is determined by matching with the outer solutions. The distinguished limit of Brownian diffusion with a weak thermal diffusion is also analysed and shown to match the two cases mentioned above.

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