共查询到20条相似文献,搜索用时 921 毫秒
1.
Peixiong Lin 《Archive for Rational Mechanics and Analysis》1990,112(2):161-191
Communicated by C. Dafermos 相似文献
2.
Permanent capillary gravity waves on the free surface of a two dimensional inviscid fluid of infinite depth are investigated. An application of the hodograph transform converts the free boundary-value problem into a boundary-value problem for the Cauchy-Riemann equations in the lower halfplane with nonlinear differential boundary conditions. This can be converted to an integro-differential equation with symbol –k
2+4|k|–4(1+), where is a bifurcation parameter. A normal-form analysis is presented which shows that the boundary-value problem can be reduced to an integrable system of ordinary differential equations plus a remainder term containing nonlocal terms of higher order for || small. This normal form system has been studied thoroughly by several authors (Iooss &Kirchgässner [8],Iooss &Pérouème [10],Dias &Iooss [5]). It admits a pair of solitary-wave solutions which are reversible in the sense ofKirchgässner [11]. By applying a method introduced in [11], it is shown that this pair of reversible solitary waves persists for the boundary-value problem, and that the decay at infinity of these solitary waves is at least like 1/|x|. 相似文献
3.
Dr.-Ing. Elmar Achenbach 《Heat and Mass Transfer》1971,4(3):152-155
The behaviour of the flow through an in-line tube bank is studied at variable roughness conditions of the surface. The total pressure loss, the local static pressure and the skin friction distribution were measured in the range of Reynolds numbers 4·104<Re<107. Opposing to the staggered arrangement the drag coefficient of an in-line bundle diminishes in the transcritical flow range with increasing roughness parameters. As at the same time heat transfer is improved the in-line bundle is of great practical interest. By means of the local flow parameters the interaction of the point of impact, separation point of the boundary layer and wake width can be pointed out.
Nomenclature D m tube diameter - k s m sand grain roughness - L m tube length - p N/m2 pressure - s 1 m longitudinal pitch - s tm transversal pitch - U c m/s velocity in the smallest cross section between the tubes - z number of rows Greek symbols pressure drop coefficient (index t=total, index f=friction) - kg/sm fluid viscosity - kg/m3 fluid density - 0 N/m2 wall shear stresses - grd angle of circumference Characteristics Reynolds number - pressure drop coefficient The investigations have been carried out in the Institut für Reaktorbauelemente der Kernforschungsanlage Jülich GmbH The author wishes to thank Dr.von der Decken, new director of the institute, who supported the already started work in its final stages with great interest. He also expresses his gratitude to his co-workers H.Gillessen, F.Hoffmanns, H.Reger, W.Schmidt and G.Türk for their activity and engagement to bring these investigations to a successful end. 相似文献
Zusammenfassung Die Strömung durch ein fluchtendes Rohrbündel glatter und rauher Oberfläche wird untersucht. Der Gesamtdruckverlust sowie die örtliche Druck- und Wandschubspannungsverteilung wurden im Bereich der ReynoldsZahlen 4·104<Re<107 gemessen. Im Gegensatz zum versetzten Wärmetauscher verringert sich bei der fluchtenden Anordnung im transkritischen Strömungsbereich der Widerstandsbeiwert mit zunehmender Oberflächenrauhigkeit. Da gleichzeitig eine Verbesserung des Wärmeüberganges beobachtet wird, kommt dem fluchtenden Bündel große praktische Bedeutung zu. Anhand der experimentell gewonnenen örtlichen Strömungsparameter wird die Wechselwirkung von Auftreffpunkt der Strömung, Grenzschichtablösung und Nachlauf breite verdeutlicht.
Nomenclature D m tube diameter - k s m sand grain roughness - L m tube length - p N/m2 pressure - s 1 m longitudinal pitch - s tm transversal pitch - U c m/s velocity in the smallest cross section between the tubes - z number of rows Greek symbols pressure drop coefficient (index t=total, index f=friction) - kg/sm fluid viscosity - kg/m3 fluid density - 0 N/m2 wall shear stresses - grd angle of circumference Characteristics Reynolds number - pressure drop coefficient The investigations have been carried out in the Institut für Reaktorbauelemente der Kernforschungsanlage Jülich GmbH The author wishes to thank Dr.von der Decken, new director of the institute, who supported the already started work in its final stages with great interest. He also expresses his gratitude to his co-workers H.Gillessen, F.Hoffmanns, H.Reger, W.Schmidt and G.Türk for their activity and engagement to bring these investigations to a successful end. 相似文献
4.
Michael Hayes 《Archive for Rational Mechanics and Analysis》1988,100(3):265-273
Communicated by K. R. Rajagopal
For
Máirín
and
Siobhán 相似文献
5.
The maximum principle for viscosity solutions of fully nonlinear second order partial differential equations 总被引:4,自引:0,他引:4
Robert Jensen 《Archive for Rational Mechanics and Analysis》1988,101(1):1-27
We prove that viscosity solutions in W
1, of the second order, fully nonlinear, equation F(D
2
u, Du, u) = 0 are unique when (i) F is degenerate elliptic and decreasing in u or (ii) F is uniformly elliptic and nonincreasing in u. We do not assume that F is convex. The method of proof involves constructing nonlinear approximation operators which map viscosity subsolutions and supersolutions onto viscosity subsolutions and supersolutions, respectively. This method is completely different from that used in Lions [8, 9] for second order problems with F convex in D
2
u and from that used by Crandall & Lions [3] and Crandall, Evans & Lions [2] for fully nonlinear first order problems.The research reported here was supported in part by grants from the Alfred P. Sloan Foundation and the National Science Foundation. 相似文献
6.
V. Nesi 《Archive for Rational Mechanics and Analysis》1996,134(1):17-51
A recent theorem due to Astala establishes the best exponent for the area distortion of planar K-quasiconformal mappings. We use a refinement of Astala's theorem due to Eremenko and Hamilton to prove new bounds on the effective conductivity of two-dimensional composites. The bounds are valid for composites made of an arbitrary finite number n of possibly anisotropic phases in prescribed volume fractions. For n= 2 we prove the optimality of the bounds under certain additional assumptions on the G-closure parameters. 相似文献
7.
Eberhard Zeidler 《Archive for Rational Mechanics and Analysis》1971,41(2):81-107
Ohne ZusammenfassungHerrn Prof. Herbert Beckert
zum 50. Geburtstag
Vorgelegt von J. Serrin 相似文献
8.
Dedicated to
James B. Serrin
on the occasion of his sixtieth birthday 相似文献
9.
C. M. Dafermos 《Archive for Rational Mechanics and Analysis》1989,107(2):127-155
In Memoriam
Ronald J. DiPerna 相似文献
10.
A. W. Marris 《Archive for Rational Mechanics and Analysis》1988,102(4):377-384
Dedicated to Professor
Bernard D. Coleman 相似文献
11.
Gaetano Fichera 《Archive for Rational Mechanics and Analysis》1979,70(2):101-112
Dedicata a
Clifford A. Truesdell
nel Suo 60 compleanno 相似文献
12.
The assumption that the Mach reflection which is formed over the second surface of a double wedge with angles
w
1
and
kw/2 approaches asymptotically the Mach reflection which would have been obtained by an identical incident shock wave over a single wedge with an angle
w =
w
2
was verified experimentally. The verification of this assumption supports the shock polar analysis suggested by Ben-Dor et al. (1987) for the study of the reflection process of a planar shock wave over a double wedge. Measurements of the rate of approach to the asymptotic value are also provided. 相似文献
13.
Martin Kummer 《Archive for Rational Mechanics and Analysis》1985,91(1):55-82
We study a particular class of perturbations of the classical Kepler Hamiltonian, first in two, then in three and finally in n dimensions. At every stage of our investigation the group theoretical nature of our constructions is fully exposed.In particular we present a new regularization of the n-dimensional Kepler problem which is based on previous constructions of Guillemin & Sternberg (see [8]). This regularization is similarily related to Moser's (see [9]) as is Kustaanheimo-Stiefel's (see [4]) in three dimensions. 相似文献
14.
Giuseppe Grioli 《Archive for Rational Mechanics and Analysis》1989,105(3):191-204
Communicated by M. E. Gurtin &; C. Truesdell 相似文献
15.
Peter Werner 《Archive for Rational Mechanics and Analysis》1960,6(1):231-260
Ohne Zusammenfassung
Vorgelegt von C. Müller
Zur praktischen Berechnung von U können nach Satz 2 die numerischen Methoden zur Auflösung Fredholmscher Integralgleichungen, etwa das Verfahren von Cl. Müller [10], verwendet werden. 相似文献
16.
LAURE SAINT-RAYMOND 《Archive for Rational Mechanics and Analysis》2003,166(1):47-80
We consider here the problem of deriving rigorously, for well-prepared initial data and without any additional assumption,
dissipative or smooth solutions of the incompressible Euler equations from renormalized solutions of the Boltzmann equation.
This completes the partial results obtained by Golse [B. Perthame and L. Desvillettes eds., Series in Applied Mathematics 4 (2000), Gauthier-Villars, Paris] and Lions & Masmoudi [Arch. Rational Mech. Anal. 158 (2001), 195–211].
(Accepted June 6, 2002) Published online December 3, 2002
Communicated by Y. BRENIER 相似文献
17.
Ohne Zusammenfassung
Vorgelegt von L. Collatz
II. Teil einer bei der Naturwissenschaftlich-Philosophischen Fakultät der Technischen Hochschule zu Braunschweig eingereichten Dissertation. Referenten: Prof. Dr. R. Iglisch und Prof. Dr. H.-J. Kanold. Auch Herrn Dr. H. Eltermann bin ich für wertvolle Ratschläge zu großem Dank verpflichtet. 相似文献
18.
Jacob Burbea 《Archive for Rational Mechanics and Analysis》1981,77(4):349-358
We derive an evolution equation for the motions of patches of vorticity (vortex). Steady state solutions of this equation that include those of Kirchhoff and Moore & Saffman are established. The m-fold symmetric, m3, hypotrochoid is an exact steady solution of this equation when rotation and strain are present. When strain is absent but rotation is present, the m-fold symmetric, m2, hypotrochoid is a perturbation solution with a dispersion relation extending that of Lamb. The case of m=2 is exact and is the Kirchhoff elliptical vortex. 相似文献
19.
Lothar Jentsch 《Archive for Rational Mechanics and Analysis》1967,24(2):141-172
Ohne Zusammenfassung
Vorgelegt von H. Beckert
Den Herren Professoren H. Beckert und R. Klötzler möchte ich an dieser Stelle für das Interesse am Entstehen dieser Arbeit herzlich danken. 相似文献
20.
We present convergence results for an adaptive algorithm to compute free energies, namely the adaptive biasing force (ABF)
method (Darve and Pohorille in J Chem Phys 115(20):9169–9183, 2001; Hénin and Chipot in J Chem Phys 121:2904, 2004). The free energy is the effective potential associated to a so-called reaction coordinate ξ(q), where q = (q
1, … , q
3N
) is the position vector of an N-particle system. Computing free energy differences remains an important challenge in molecular dynamics due to the presence
of metastable regions in the potential energy surface. The ABF method uses an on-the-fly estimate of the free energy to bias
dynamics and overcome metastability. Using entropy arguments and logarithmic Sobolev inequalities, previous results have shown
that the rate of convergence of the ABF method is limited by the metastable features of the canonical measures conditioned
to being at fixed values of ξ (Lelièvre et al. in Nonlinearity 21(6):1155–1181, 2008). In this paper, we present an improvement on the existing results in the presence of such metastabilities, which is a generic
case encountered in practice. More precisely, we study the so-called bi-channel case, where two channels along the reaction
coordinate direction exist between an initial and final state, the channels being separated from each other by a region of
very low probability. With hypotheses made on ‘channel-dependent’ conditional measures, we show on a bi-channel model, which
we introduce, that the convergence of the ABF method is, in fact, not limited by metastabilities in directions orthogonal
to ξ under two crucial assumptions: (i) exchange between the two channels is possible for some values of ξ and (ii) the free energy is a good bias in each channel. This theoretical result supports recent numerical experiments (Minoukadeh et al. in J Chem Theory Comput 6:1008–1017, 2010), where the efficiency of the ABF approach is demonstrated for such a multiple-channel situation. 相似文献