An experimental investigation of the flow field for double-wedge configurations in a Mach 4.97 stream

The viscous-inviscid interactions which perturb the flow around the wing leading edge are discussed. The flow field perturbation results when the fuselage-generated shock wave interacts with the wing-generated shock wave. Three types of shock interference patterns are possible for the wing leading edge of the orbiter

Indirect Detection of CMSSM Neutralino Dark Matter with Neutrino Telescopes

We review the prospects of detecting supersymmetric dark matter in the framework of the Constrained Minimal Supersymmetric Standard Model, and compare indirect with direct detection capabilities.Comment: 6 pages, 4 figures, presented by J. Orloff at the York IDM02 workshop (http://www.shef.ac.uk/~phys/idm2002

Neutrino Indirect Detection of Neutralino Dark Matter in the CMSSM

We study potential signals of neutralino dark matter indirect detection by neutrino telescopes in a wide range of CMSSM parameters. We also compare with direct detection potential signals taking into account in both cases present and future experiment sensitivities. Only models with neutralino annihilation into gauge bosons can satisfy cosmological constraints and current neutrino indirect detection sensitivities. For both direct and indirect detection, only next generation experiments will be able to really test this kind of models.Comment: 16 pages, 19 figures; v4: a few clarifications and significant improvement of reference

Analysis of a two-dimensional type 6 shock-interference pattern using a perfect-gas code and a real-gas code

Numerical codes were developed to calculate the two dimensional flow field which results when supersonic flow encounters double wedge configurations whose angles are such that a type 4 pattern occurs. The flow field model included the shock interaction phenomena for a delta wing orbiter. Two numerical codes were developed, one which used the perfect gas relations and a second which incorporated a Mollier table to define equilibrium air properties. The two codes were used to generate theoretical surface pressure and heat transfer distributions for velocities from 3,821 feet per second to an entry condition of 25,000 feet per second

Relaxation of spherical systems with long-range interactions: a numerical investigation

The process of relaxation of a system of particles interacting with long-range forces is relevant to many areas of Physics. For obvious reasons, in Stellar Dynamics much attention has been paid to the case of 1/r^2 force law. However, recently the interest in alternative gravities emerged, and significant differences with respect to Newtonian gravity have been found in relaxation phenomena. Here we begin to explore this matter further, by using a numerical model of spherical shells interacting with an 1/r^alpha force law obeying the superposition principle. We find that the virialization and phase-mixing times depend on the exponent alpha, with small values of alpha corresponding to longer relaxation times, similarly to what happens when comparing for N-body simulations in classical gravity and in Modified Newtonian Dynamics.Comment: 6 pages, 3 figures, accepted in the International Journal of Bifurcation and Chao

Global fluctuations and Gumbel statistics

We explain how the statistics of global observables in correlated systems can be related to extreme value problems and to Gumbel statistics. This relationship then naturally leads to the emergence of the generalized Gumbel distribution G_a(x), with a real index a, in the study of global fluctuations. To illustrate these findings, we introduce an exactly solvable nonequilibrium model describing an energy flux on a lattice, with local dissipation, in which the fluctuations of the global energy are precisely described by the generalized Gumbel distribution.Comment: 4 pages, 3 figures; final version with minor change

Shuttle orbiter boundary layer transition at flight and wind tunnel conditions

Hypersonic boundary layer transition data obtained on the windward centerline of the Shuttle orbiter during entry for the first five flights are presented and analyzed. Because the orbiter surface is composed of a large number of thermal protection tiles, the transition data include the effects of distributed roughness arising from tile misalignment and gaps. These data are used as a benchmark for assessing and improving the accuracy of boundary layer transition predictions based on correlations of wind tunnel data taken on both aerodynamically rough and smooth orbiter surfaces. By comparing these two data bases, the relative importance of tunnel free stream noise and surface roughness on orbiter boundary layer transition correlation parameters can be assessed. This assessment indicates that accurate predications of transition times can be made for the orbiter at hypersonic flight conditions by using roughness dominated wind tunnel data. Specifically, times of transition onset and completion is accurately predicted using a correlation based on critical and effective values of a roughness Reynolds number previously derived from wind tunnel data

Experimental and theoretical study of shuttle lee-side heat transfer rates

The experimental program which was conducted in the Calspan 96-inch hypersonic shock tunnel to investigate what effect the windward surface temperature had on the heat transfer to the leeward surface of the space shuttle orbiter is discussed. Heat-transfer distributions, surface-pressure distributions, and schlieren photographs were obtained for an 0.01-scale model of the 139 configuration space shuttle orbiter at angles-of-attack of 30 and 40 deg. Similar data were obtained for an 0.01 scale wingless model of the 139 configuration at angles-of-attack of 30 and 90 deg. Data were obtained for Mach numbers from Reynolds numbers, and surface temperatures and compared with theoretical results

Flow field for an underexpanded, supersonic nozzle exhausting into an expansive launch tube

Static pressure distributions along the launcher wall and pitot pressure measurements from the annular region between the rocket and the launcher were made as an underexpanded supersonic nozzle exhausted into an expansive launch tube. The flow remained supersonic along the entire length of the launcher for all nozzle locations studied

The Kovacs effect in model glasses

We discuss the `memory effect' discovered in the 60's by Kovacs in temperature shift experiments on glassy polymers, where the volume (or energy) displays a non monotonous time behaviour. This effect is generic and is observed on a variety of different glassy systems (including granular materials). The aim of this paper is to discuss whether some microscopic information can be extracted from a quantitative analysis of the `Kovacs hump'. We study analytically two families of theoretical models: domain growth and traps, for which detailed predictions of the shape of the hump can be obtained. Qualitatively, the Kovacs effect reflects the heterogeneity of the system: its description requires to deal not only with averages but with a full probability distribution (of domain sizes or of relaxation times). We end by some suggestions for a quantitative analysis of experimental results.Comment: 17 pages, 6 figures; revised versio