Showing papers on "Obstacle published in 1968"
TL;DR: In this article, the wave-guide analogy is further developed and several uniqueness theorems obtained for the steady two-dimensional flow of an inviscid incompressible fluid of variable density in a long channel bounded above by a rigid horizontal plane and below by an obstacle.
Abstract: The steady two-dimensional flow of an inviscid incompressible fluid of variable density is considered in a long channel, bounded above by a rigid horizontal plane and below by an obstacle. For certain variations with height of the speed aud density in the incident stream, the governing equation is the reduced wave equation. Drazin & Moore (1967) have recently used this fact to develop a waveguide analogy. In this note the wave-guide analogy is further developed and several uniqueness theorems obtained. When the obstacle satisfies a certain convexity condition it is shown that the upstream conditions and the obstacle uniquely determine the flow; that is, there is no critical internal Froude number or obstacle height for which the problem fails to be well posed.
8 citations
TL;DR: In this article, the influence of a knife-edge obstacle on radio propagation over a curved surface was investigated and it was shown that the effect of the obstacle is strongly dependent on the location relative to the path terminals.
Abstract: Some calculated results are given for influence of a knife-edge obstacle on radio propagation over a curved surface. A special case, of a previous formulation, is employed for the calculations. It is shown that the effect of the obstacle is strongly dependent on the location relative to the path terminals. This note is an addendum to the paper “Diffraction and scattering of the electromagnetic ground wave by terrain features”, Radio Sci. 3 (New Series), No. 10, 1968.
6 citations
TL;DR: In this article, the analytical and geometrical properties of a curve generated by the apex of an inverted V-shaped obstacle are investigated in a co-ordinate system fixed to a wheeled vehicle which is passing over the obstacle.
5 citations
TL;DR: In this article, the authors discuss the problems associated with the operation of vehicles in and near waterways, and suggest that dramatic improvements in vehicle egress capabilities are required in areas where amphibious and wading craft encounter impassable banks.
2 citations
01 Jun 1968
TL;DR: In this article, an investigation of the three-dimensional, incompressible wake behind a blunt obstacle located at the leading edge of a flat plate is presented, which is characterized by a region of strong vorticity immediately behind the obstacle followed by viscous dissusion.
Abstract: : An investigation of the three-dimensional, incompressible wake behind a blunt obstacle located at the leading edge of a flat plate is presented. Configurations studied included the 'clean' flat plate, and the flat plate with a rectangular, a square, or a two-dimensional obstacle fitted to the leading edge of the plate. Experimental results are compared to a mathematical model based on the Oseen linearization for diffusive flows. Based on mean flow measurements, a transition to turbulent flow was not encountered for any of the configurations examined. Such wakes are characterized by a region of strong vorticity immediately behind the obstacle followed by a region of viscous dissusion. Bulk properties of the wake-like flow and the applicability of the theoretical model were found to be highly dependent on the geometry of the obstacle. (Author)
1 citations
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1 citations