ISSN:0025-5793    

DOI:10.1112/S0025579300016478

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

摘要:

SummaryA recent paper [1] indicates that the beginnings of dynamic stall, near an aerofoil's leading edge, for instance, can be regarded as the finite‐time nonlinear breakdown of a boundary layer subjected to an angle of attackabovethe critical value for the existence of a steady solution. The present theoretical study shows that the same non‐linear breakdown can occur even in thebelow‐critical regime. This happens particularly when reversed flow is present since short wavelength disturbances are then unstable and accumulate, for certain confined initial conditions, to force the finite‐time collapse. A number of marginal cases with forward or reversed, subsonic or supersonic, oncoming motion are also noted and shed extra light on the instability and subsequent breakdown.

ISSN:0025-5793    

DOI:10.1112/S0025579300012407

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

摘要:

AsbtractAttempts to extend known two‐dimensional results (Ursell, 1947) to the fully three‐dimensional case can lead to unpredictable results. We show how the use of a variational approximation for a finite plane vertical barrier leads to apparently different results when different formulations are used. The reason for this is not so much that the method is wrong, but rather that several different limits are taken in the process, which are hard to control. We suggest an alternative matching scheme, based on Ayad and Leppington (1977), which holds for the case ka → ∞,l/a → ∞,kl→ ∞, where / is the length of the barrier,aits depth andkthe wavelength of the incident wave. The method is applied to a channel with impeding side walls, as a model of French's (1977) wave‐energy device.

ISSN:0025-5793    

DOI:10.1112/S0025579300012419

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

摘要:

SummaryIn this paper the authors formulate a boundary‐initial value problem for a linear elastic porous body saturated with an inviscid fluid and establish a continuous dependence theorem (Theorem 2) and two uniqueness theorems (Theorems 3, 4) for a particular class of such continua. Theorems 2, 3 are proved without hypotheses on the sign of the constants and, if the domain is unbounded, under mild assumptions on the spatial asymptotic behaviour of the field variables. Theorem 4 holds for body‐forces not equal to zero and, if the domain is unbounded, without restrictions upon the behaviour of the unknown fields at infinity, but under suitable conditions on the sign of the constants.

ISSN:0025-5793    

DOI:10.1112/S0025579300012420

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

ISSN:0025-5793    

DOI:10.1112/S0025579300012432

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

ISSN:0025-5793    

DOI:10.1112/S0025579300012444

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

ISSN:0025-5793    

DOI:10.1112/S0025579300012456

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

ISSN:0025-5793    

DOI:10.1112/S0025579300012468

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

摘要:

AbstractIt is proved here that, ifGis a positive definite integral ternary quadratic lattice of discriminantdandcis a squarefree integer which is primitively represented by the genus ofG, thenGprimitively represents all sufficiently large integers of the typect2, with g.c.d. (t, 2d) = 1, which are primitively represented by the spinor genus ofG.

ISSN:0025-5793    

DOI:10.1112/S002557930001247X

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY

ISSN:0025-5793    

DOI:10.1112/S0025579300012481

出版商:London Mathematical Society    

年代:1984

数据来源: WILEY