GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 12 (2000), S. 1955-1968 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The rate of viscous energy dissipation in a shear layer of incompressible Newtonian fluid with injection and suction is studied by means of exact solutions, nonlinear and linearized stability theory, and rigorous upper bounds. The injection and suction rates are maintained constant and equal and this leads to solutions with constant throughput. For strong enough suction, expressed in terms of the entry angle between the injection velocity and the boundaries, a steady laminar flow is nonlinearly stable for all Reynolds numbers. For a narrow range of small but nonzero angles, the laminar flow is linearly unstable at high Reynolds numbers. The upper bound on the energy dissipation rate—valid even for turbulent solutions of the Navier–Stokes equations—scales with viscosity in the same way as the laminar dissipation in the vanishing viscosity limit. For both the laminar and turbulent flows, the energy dissipation rate becomes independent of the viscosity for high Reynolds numbers. Hence the laminar energy dissipation rate and the largest possible turbulent energy dissipation rate for flows in this geometry differ by only a prefactor that depends only on the angle of entry. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 8 (1998), S. 643-649 
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The constructive role of random fluctuations is studied in the context of transport in stochastic ratchets. We discuss the interplay of independent white (thermal) and discrete (external) noises and their generation of transport in anisotropic potentials. The constructive cooperation of such fluctuations is most apparent in the asymptotic limit of fast discrete-valued noise, a limit which presents some interesting mathematical features. We describe the asymptotic analysis of the current in the limit of fast external noise, pointing out the strong qualitative dependence of the current on the interplay of the independent noise sources and its surprising sensitivity to the regularity of the underlying anisotropic ratchet potential. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 42 (2001), S. 784-795 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Bounds for the bulk heat transport in Rayleigh–Benard convection for an infinite Prandtl number fluid are derived from the primitive equations. The enhancement of heat transport beyond the minimal conduction value (the Nusselt number Nu) is bounded in terms of the nondimensional temperature difference across the layer (the Rayleigh number Ra) according to Nu≤cRa2/5, where c〈1 is an absolute constant. This rigorous upper limit is uniform in the rotation rate when a Coriolis force, corresponding to the rotating convection problem, is included. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 37 (1996), S. 6152-6156 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: We derive rigorous bounds on the length scale of determining local averages (volume elements) for the 3-D Navier-Stokes Equations. These length scale estimates are related to Kolmogorov's notion of a dissipation length scale in turbulent flows. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 7 (1995), S. 1384-1390 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a method developed by Foias and Temam [J. Funct. Anal. 87, 359 (1989)], exponential decay of the spatial Fourier power spectrum for solutions of the incompressible Navier–Stokes equations is established and explicit rigorous lower bounds on a small length scale defined by the exponential decay rate are obtained. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 54 (1989), S. 1111-1119 
    ISSN: 1572-9613
    Keywords: Stochastic processes ; nonequilibrium phenomena ; colorednoise ; multiplicative noise ; nonlinear dynamics ; transition to turbulence ; spatial degrees of freedom ; external noise ; hydrodynamic instabilities ; pattern formation ; nonlinear optics ; limits of computation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A brief introduction to the field is given together with an overview of the lectures given at the workshop on External Noise and its Interaction with Spatial Degrees of Freedom in Nonlinear Dissipative Systems organized by the Center for Nonlinear Studies at Los Alamos, March 28–31, 1988. It is hoped that the publication of papers presented at the workshop in a single issue of theJournal of Statistical Physics will help draw attention to the recent developments in this rapidly area of nonequilibrium phenomena.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 54 (1989), S. 1321-1352 
    ISSN: 1572-9613
    Keywords: Exit times ; first passage times ; colored noise ; Ornstein-Uhlenbeck process ; half-range expansion ; singular perturbation methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We analyze the exit time (first passage time) problem for the Ornstein-Uhlenbeck model of Brownian motion. Specifically, consider the positionX(t) of a particle whose velocity is an Ornstein-Uhlenbeck process with amplitudeσ/ρ and correlation time ε2, $$dX/dt = \sigma Z/\varepsilon , dZ/dt = - Z/\varepsilon ^2 + 2^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} \xi (t)/\varepsilon $$ whereξ(t) is Gaussian white noise. Let the exit timet ex be the first time the particle escapes an interval −A〈X(t)〈B, given that it starts atX(0)=0 withZ(0)=z 0. Here we determine the exit time probability distributionF(t)≡Prob {t ex〉t} by directly solving the Fokker-Planck equation. In brief, after taking a Laplace transform, we use singular perturbation methods to reduce the Fokker-Planck equation to a boundary layer problem. This boundary layer problem turns out to be a half-range expansion problem, which we solve via complex variable techniques. This yields the Laplace transform ofF(t) to within a transcendentally smallO(e −A/εσ +e −B/εσ error. We then obtainF(t) by inverting the transform order by order in ε. In particular, by lettingB→∞ we obtain the solution to Wang and Uhlenbeck's unsolved problem b; throughO(ε2σ2/A 1) this solution is $$F(t) = Erf\left\{ {\frac{{A + \varepsilon \sigma \alpha + \varepsilon \sigma z_0 }}{{2\sigma (t - \varepsilon ^2 \kappa )^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} }}} \right\} + ... for \frac{t}{{\varepsilon ^2 }} 〉 〉 1$$ andF=1 otherwise. Here, α=∥ξ(1/2)∥=1.4603⋯, where ξ is the Riemann zeta function, and the constant κ is 0.22749⋯.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 83 (1996), S. 359-383 
    ISSN: 1572-9613
    Keywords: Algorithm ; stochastic ; transport ; ratchets ; nonequilibrium ; detailed balance ; master equation ; jump process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a numerical simulation algorithm that is well suited for the study of noise-induced transport processes. The algorithm has two advantages over standard techniques: (1) it preserves the property of detailed balance for systems in equilibrium and (2) it provides an efficient method for calculating nonequilibrium currents. Numerical results are compared with exact solutions from two different types of correlation ratchets, and are used to verify the results of perturbation calculations done on a three-state ratchet.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 94 (1999), S. 159-172 
    ISSN: 1572-9613
    Keywords: Nusselt number ; convection ; heat transport ; turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We prove an inequality of the type N≤CR 1/3(1+log+ R)2/3 for the Nusselt number N in terms of the Rayleigh number R for the equations describing three-dimensional Rayleigh–Bénard convection in the limit of infinite Prandtl number.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 109 (1987), S. 537-561 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We prove the existence of solutions to the nonlinear parabolic stochastic differential equation $$({\partial \mathord{\left/ {\vphantom {\partial {\partial t}}} \right. \kern-\nulldelimiterspace} {\partial t}} - \Delta )\varphi = - V'(\varphi ) + \eta _c $$ for polynomialsV of even degree with positive leading coefficient and ν c a gaussian colored noise process onR d ×R +. When ν c is colored enough that the gaussian solution to the linear problem has Hölder continuous covariance, the nongaussian processes are almost surely realized by continuous functions. Uniqueness, regularity properties, asymptotic perturbation expansions and nonperturbative fluctuation bounds are obtained for the infinite volume processes. These equations are a cutoff version of the Parisi-Wu stochastic quantization procedure forP(ϕ) d models, and the results of this paper rigorously establish the nonperturbative nature of regularization via modification of the noise process. In the limit ν c → gaussian white noise we find that the asymptotic expansion and the rigorous bounds agree for processes corresponding to the (regulated) stochastic quantization of super-renormalizable and small coupling, strictly renormalizable scalar field theories and disagree for nonrenormalizable models.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...