8,410 research outputs found
Understanding Gravity: Some Extra Dimensional Perspectives
Gravity is one of the most inexplicable forces of nature, controlling
everything, from the expansion of the Universe to the ebb and flow of ocean
tides. The search for the laws of motion and gravitation began more than two
thousand years ago but still we do not have the complete picture of it. In this
article, we have outlined how our understanding of gravity is changing
drastically with time and how the previous explanations have shaped the most
recent developments in the field like superstrings and braneworlds.Comment: 21 page
Numerical investigation of V/STOL jet induced interactions
Direct numerical simulation using the full three dimensional, time dependent Navier-Stokes equations is used to investigate V/STOL jet induced interactions. The objective of this numerical simulation is to compute accurately the details of the flow field and to achieve a better understanding of the physics of the flow, including the role of initial turbulence in the jet, the influence of forward motion on hover aerodynamics, the collision zone and fountain characteristics. Preliminary results are presented
Gravity and Large Extra Dimensions
The idea that quantum gravity can be realized at the TeV scale is extremely
attractive to theorists and experimentalists alike. This proposal leads to
extra spacial dimensions large compared to the electroweak scale. Here we give
a very systematic view of the foundations of the theories with large extra
dimensions and their physical consequences.Comment: 26 pages, 3 diagram
Mass flux similarity for slotted transonic-wind-tunnel walls
A discussion of the flow field measurements obtained in the vertical plane at several stations along the centerline of slots in two different longitudinally slotted wind tunnel walls is presented. The longitudinal and transverse components of the data are then transformed using the concept of flow similarity to demonstrate the applicability of the technique to the development of the viscous shear flow along and through a slotted wall of an airfoil tunnel. Results are presented showing the performance of the similarity transformations with variations in tunnel station, Mach number, and airfoil induced curvature of the tunnel free stream
Plasmon Annihilation into Kaluza-Klein Graviton: New Astrophysical Constraints on Large Extra Dimensions
In large extra dimensional Kaluza-Klein (KK) scenario, where the usual
Standard Model (SM) matter is confined to a 3+1-dimensional hypersurface called
the 3-brane and gravity can propagate to the bulk (D=4+d, d being the number of
extra spatial dimensions), the light graviton KK modes can be produced inside
the supernova core due to the usual nucleon-nucleon bremstrahlung,
electron-positron and photon-photon annihilations. This photon inside the
supernova becomes plasmon due to the plasma effect. In this paper, we study the
energy-loss rate of SN 1987A due to the KK gravitons produced from the
plasmon-plasmon annihilation. We find that the SN 1987A cooling rate leads to
the conservative bound > 22.9 TeV and 1.38 TeV for the case of two and
three space-like extra dimensions.Comment: 13 pages, 1 ps figure, text is modified a little bit, conclusion
unchanged, new references are added, version accepted for publication in PR
Theoretical methods and design studies for NLF and HLFC swept wings at subsonic and supersonic speeds
Laminarization of the boundary layer on the surface of aircraft wings can be accomplished by the use of concepts such as Natural Laminar Flow (NLF), Laminar-Flow Control (LFC), and Hybrid Laminar-Flow Control (HLFC). Several integral boundary-layer methods were developed for the prediction of laminar, transition, and separating turbulent boundary layers. These methods were developed for use at either subsonic or supersonic speeds, have small computer execution times, and are simple to use. The theoretical equations and assumptions which form the basis of the boundary-layer method, are briefly outlined and the results of several correlation cases with exciting experimental data are presented
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