In a rectangular cross-section wind tunnel a separated oblique shock reflection is set to interact with the turbulent boundary layer (oblique SBLI) both on the bottom wall and in the corner formed by the intersection of the floor with the side-walls. In such a scenario, shock-induced separation is often seen in each of the streamwise corners, resulting in a highly three-dimensional flow field in the near-wall region. To examine how the corner separations can affect the `quasi-two-dimensional' main interaction and by what mechanism this is achieved, an experimental investigation has been conducted. This examines how modifications to the corner separation influence an oblique shock reflection. The nature of the flow field is studied using flow visualisation, Pressure Sensitive Paint and Laser Doppler Anemometry. A nominal freestream Mach number of 2.5 is used for all experiments with a unit Reynolds number of $40\times10^6$m$^{-1}$, and the shock-generator angle is set to $8^\circ$. The flow conditions are chosen to result in substantial separations both in the corners and along the centreline for the baseline case, which is thought to be a good starting point for this study. The results show that the size and shape of central separation vary considerably when the onset and magnitude of corner separation change. The primary mechanism coupling these separated regions appears to be the generation of compression waves and expansion fans as a result of the displacement effect of the corner separation. The presence and strength of the expansion waves have been overlooked in previous studies. This is shown to modify the three-dimensional shock-structure and alter the adverse pressure gradient experienced by the tunnel floor boundary layer. It is suggested that a typical oblique SBLI in rectangular channels features several zones depending on the relative position of the corner waves and the main interaction domain. In particular, it has been shown that the position of the corner `shock' crossing point, found by approximating the corner compression waves by a straight line, is a critical factor determining the main separation size and shape. Thus, corner effects can substantially modify the central separation. This can cause significant growth or contraction of the separation length measured along the symmetry line from the nominally two-dimensional baseline value, giving a fivefold increase from the smallest to the largest observed value. Moreover, the shape and flow topology of the centreline separation bubble is also considerably changed by varying corner effects.

Two foams, a polyether (density 32.5 kg/m3) and a polyester (density 38 kg/m3) foam were tested in a shock tube to analyze the interaction of a normal shock wave and a compressible porous material. The foam specimens were placed in the shock tube test section! the foam being bounded by two steel walis, two glass windows and a solid back plate. The compression chamber of the shock tube was pressurized and the diaphragm separating the compression chamber and the expansion chamber was ruptured, thus producing a normal shock wave which travels down the shock tube and strikes the foam. Piezoelectric pressure transducers 'vvera used to record the pressure before, alongside and behind the foam. A complete set of schlieren photographs, recording the interaction of the incident shock wave and the porous material were taken for each foam. A method ,tortracking the path of particles of foam (path photographs) was developed. Combining the information obtained from the pressure records, schlieren photographs and path photographs a complete picture of the shock wave foam interaction was developed. All the gas waves were identified and analyzed, A foam wave (velocity 90 m/s) travelling through the skeleton of the material was discovered. A physical model was developed to explain the high pressure recorded behind the foam. This model is based upon the foam being compressed and forming an almost solid piston, thus forcing the trapped gas into a diminishing volume and creating a high pressure behind the foam. The theoretical analyses of Monti (30), Gel'fand (20) and IBvozdeva (22) were analyz.ed and compared. The general finding was that for the range of incident mach numbers 1.~i1 to 1.46 Monti's analysis under predicts the reflected Mach number by 3 % and Gel'fand's analysis over predicts the reflected Mach number by 6 %. The coefficient of pressure increase (the ratio of the maximum pressure recorded behind the foam to the equivalent pressure recorded during ~he reflection of a shock wave from a solid wall) as predicted iJy Gvoz.deva's ane.lysisfor the polyether foam lies wjthin the scatter of the experimental results. However for the polyester foam Gvozdeva's analysis under predicts the coefficient of pressure increase by 15%. / GR 2016

Shocked porous granular material experiences pressure dependent compaction. D. John Pastine introduced a model in which the degree of compaction is dependent on the pressure induced by the shock wave, the shear strength of the material, and the distribution of void sizes. In the past, the model could only be approximated. Using computational techniques and higher speed computers, the response of this model to void size distributions may be displayed to a high degree of precision. / Graduation date: 1996

No description available.

Thesis (Ph. D.)--University of Washington, 1982. / Vita. Includes bibliographical references.

Reflection of an obliquely incident solitary wave at a vertical wall is studied experimentally in the laboratory wave tank. Precision measurements of water-surface variations are achieved with the aid of laser-induced fluorescent (LIF) technique and detailed temporal and spatial features of the Mach reflection are captured. During the development stage of the reflection process, the stem wave is formed with the wave crest perpendicular to the wall; this stem wave is not in the form of a Korteweg-de Vries (KdV) soliton but a forced wave, trailing by a continuously broadening depression wave. Evolution of stem-wave amplification is in good agreement with the Kadomtsev-Petviashvili (KP) theory. The asymptotic characteristics and behaviors are also in agreement with the theory of Miles (1977b) except those in the neighborhood of the transition between the Mach reflection and the regular reflection. The maximum fourfold amplification of the stem wave at the transition predicted by Miles is not realized in the laboratory environment: the maximum amplification measured in the laboratory is 2.92, which is however in excellent agreement with the numerical results of Tanaka (1993). The present laboratory study is the first to sensibly analyze validation of the theory; note that substantial discrepancies exist from previous (both numerical and laboratory) experimental studies. Agreement between experiments and theory can be partially attributed to the large-distance measurements that the precision laboratory apparatus is capable of. More important, to compare the laboratory results with theory, the corrected interaction parameter is derived from proper interpretation of the theory in consideration of the finite incident wave angle. Our laboratory data indicate that the maximum stem wave can reach higher than the maximum solitary wave height. The wave breaking along the wall results in the substantial increase in wave height and slope away from the wall. Extending the foregoing study on the reflection of a single solitary wave at a vertical wall, laboratory and numerical experiments are performed on two co-propagating obliquely incident solitary waves with different amplitudes that are reflected at the wall. The larger wave catches up with the smaller wave; hence the two waves collide with the strong interaction. The resulting wave pattern near the wall is complex due to the interaction among the two incident solitons and the two reflected solitons. The numerical predictions of the KP theory are in good agreement with the experimental results. Another comparison of the KP theory with laboratory experiments is demonstrated for one of the exact soliton solutions of the KP equation by Chakravarty and Kodama (2009). This solution is called the T-type solution by Kodama. The theoretically predicted formation of the 'box'-shape wave pattern in the vicinity of two-soliton intersection is realized in the laboratory tank. The agreement between the laboratory observation and the KP theory is found better for the cases with the larger wave amplitude a and smaller oblique angle ψ (i.e. tan ψ/(√3a cos ψ) < 0.6). Subtle and unavoidable differences among the analytical KP solution, the setup of numerical calculation, and the laboratory condition are discussed. / Graduation date: 2013

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No description available.

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No description available.