Unsteady wave phenomena in high-speed compressible flows

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The unifying theme of the proposed wide-scope research program is unsteady wave phenomena in high speed compressible flows. The key points here are high velocities, which make compressibility effects and wave-like nature of the phenomena under study prominent, and essential flow unsteadiness, which challenges researchers and is much less studied as compared to relevant steady gasdynamic flows. From the physico-mathematical point of view all these fluid phenomena are described by so-called hyperbolic systems of conservation laws, making it possible to treat, within the same framework of mathematical models and computer codes, the phenomena which at first superficial glance do not have much in common. In this spirit, the program encompasses four major research directions: (I) Fundamentals of essentially unsteady shock wave reflections from curved surfaces and transitions between different types of reflection: a number of issues related to physical mechanisms of these phenomena and interpretations of experimental observations have recently become a hot and contentious topic attracting many researchers; the proposed project is aimed at making crucial and decisive contributions to the debate; (II) Starting of air intakes for next-generation hypersonic air-breathing engines (scramjets): novel intake starting techniques based on unsteady effects (e.g., diaphragm-rupture induced) proposed earlier by the principal investigator will be further studied with more realistic models aiming at finding the ways of their practical implementation; an in-depth study and optimization of the widely used overboard spillage technique will be undertaken as well; (III) Shock wave phenomena in complex media as encountered in two application areas: the implosion-driven hypervelocity launcher for ground-based testing of orbital debris impact on satellites, and the shock wave propagation and cavitation bubble dynamics generated by laser pulse energy depositions in liquids as used in various medical applications of shock waves; (IV) Nonlinear magneto-acoustics: modelling of waves phase conjugation (time-reversal of acoustic signals) in heterogeneous media which has many applications in medical treatments and diagnostics, non-destructive testing and flow metrology. The main research tool of the program will be the set of high-resolution and efficient flow solvers developed earlier by the principal investigator. These numerical methods and codes are planned to be further elaborated for more accurate, efficient and reliable treatment of the above problems. Furthermore, the principal investigator forged very close collaborative ties with, arguably, world leaders in experimental diagnostics for the four research directions mentioned above (from Australia, Canada, France, Japan), who would supply their experimental data and additionally perform experiments suggested and designed by the principal investigator. Such worldwide collaboration, in the true spirit of our era of globalization, would ensure that all three modes of investigation - theoretical, experimental and numerical - are used in the most effective combination within the proposed research program. The major outcomes are expected to be discoveries of both fundamental and practical nature in the chosen research areas delivered to research and engineering community via refereed publications in archival journals; extensive training of graduate/undergraduate students in stimulating and in many aspects unique research environment, and further development of general computer codes for unsteady gasdynamics of shocked flows, which are already in use by many researchers worldwide and would undoubtedly serve as a solid base for future research undertakings and practical applications of their results.