Shock wave diffraction over a 90 degree sharp corner — Posters presented at 18th ISSW

A special poster session was run during the 18th International Symposium on Shock Waves, held on July 21 – 26, 1991, in Sendai, Japan. The purpose of this session was to compare various CFD schemes which are useful for simulating shock wave phenomena. A 2-D planar shock wave diffraction over a 90 degree sharp corner was selected as a bench mark problem. The problem specification and the output format are described below. Experimental outputs for the close flow conditions to the computational ones were also called for. Twenty six poster presentations were made at this session and the majority of the posters reflected a standard of excellence that warrants publication in the Shock Waves journal. Therefore these results are reproduced here. However, since there is a limit on the available page numbers, it was not possible to publish all the posters that were presented at the special poster session. We express our sincere thanks to all the participants in this session.     

Editorial

On behalf of the board of editors of the journal Shock Waves, I am pleased to give a brief overview of recent shock wave research activities. Shock waves are comprehensive representations of phenomena that appear in non-linear wave dynamics. Historically, shock wave phenomena started to be intensively investigated with the advent of high-speed gas-dynamics and these investigations are nowadays supported by the development of both super-computation and advanced experimental technology. Meanwhile, shock wave research has been expanding its scope to various interdisciplinary applications. A particular case is shock wave research in condensed matter which has a history as long as that of corresponding research in the field of gas-dynamics. However, although there are many dynamic similarities between shock wave motion in gases and condensed matter, the difference with respect to physical properties of both media was so dominating that for a long time research activities in these two fields have been regrettably rather isolated with only little communication between both scientific communities. Realizing that many methodologies are increasingly overlapping, it is now a good time for all of us - in the spirit of the advancement of science and technology - to try to look at shock wave phenomena in various media in order to understand their common features. The sheer variety of multi-faceted applications in shock wave research are reflected by an impressive number of international meetings such as the International Symposium on Shock Waves, the International Colloquium on the Dynamics of Explosions and Reactive Systems and the Conference on Shock Compression of Condensed Matter. In addition to these major international activities, many countries regularly organize national shock wave symposia. As a result of such activities the Asia-Pacific Shock Wave Research Society was established in 2003, whose wide membership includes researchers from the Asia-Pacific region and beyond. On the occasion of assuming the position as new Editor-in-Chief of the journal Shock Waves, I would like to thank my predecessor, Prof. Hans Grönig, for the many years of effort devoted to this task. I will continue to promote this journal as a major publishing platform that supports all international and interdisciplinary shock wave research activities and provides readers with an invaluable source of information.     

In memoriam Professor Ko Saito (1941-2004)

Professor Ko Saito of Hiroshima University suffering from hepatic cancer passed away on May 20, 2004 at the age of 63, one year before his planned retirement in March 2005. He graduated from Hiroshima University in 1964, supervised by Professor Yamamura, and started his career in high-temperature chemical reaction and was appointed to be a Research Associate of the Department of Chemistry at Hiroshima University in 1967. He received a Doctor of Science Degree in chemistry in 1973 and spent his study leave from May 1980 to March 1981 at the University of Essex UK and worked with Professor JN Bradley. He was promoted to Associate Professor in 1986 and then to Professor of the Hiroshima University in 1990.He had one hundred paper publications in well-known scientific journals, the Proceedings of International Symposia on Shock Waves (ISSW) and was an author of a Japanese text book on physical chemistry. He proved himself as an experimentalist as well as a theoretician and often told students that progress in chemical reaction studies should be maintained by conducting both experiments and analyses based on quantum chemistry. He taught a physical chemistry course to all first-year students introducing rigorously his approach.He devoted himself to identify and characterize features of molecules suddenly exposed to shock created high temperatures and particularly concentrated in thermal decomposition processes of carboxylic acid groups. These acid groups are found to decompose molecular and quantum chemical analyses supports the observation. This is one of the highlights of his achievements.He participated regularly in International and Domestic Shock Wave Symposia and intensively presented important results he and his group discovered. His latest works are presented in the Proceedings of ISSW24 held in Beijing, July 2004. Professor Saito was not only an educator but also an active chemical shock wave researcher serving continuously for 40 years and immensely contributed to establish the academic reputation of the Department of Chemistry of Hiroshima University. Undergraduate and graduate students and post doctoral fellows he once supervised are today remembering his philosophy in their mind and try to widen the world of shock wave chemistry.Published online: 18 February 2005[/PUBLISHED]     

In memoriam Dr. Werner Heilig (1933-2003)

A dear friend and colleague, Dr. Werner Heilig, died last December (2-12-2003) after a short and painful illness. Dr. Heilig was well known and respected in the world-wide shock wave family due to his contributions to our understanding of shock reflection and interaction phenomena.Dr. Werner Heilig was born in Freiburg in January 1933. He received his matriculation from the Kepler-Gymnasium in Freiburg in 1953 and immediately thereafter started studying Mathematics and Physics at the Albert-Ludwigs University in Freiburg, from which he graduated in early 1958. After graduation he took an extra two years of pedagogy studies in order to qualify as a teacher of mathematics in a high school (Gymnasium), and indeed he served as a mathematics teacher in a Gymnasium from January 1961 until March 1964. A big change in his professional career took place in April 1964 when he joined the Ernst-Mach-Institute in Freiburg. Simultaneously with his new work at the Ernst-Mach-Institute he was teaching every morning from 8 to 9 oclock mathematics at the St. Ursula Gymnasium, walking to his new place of work immediately after teaching. At that time he also started his PhD studies at the University of Karlsruhe. The title of his thesis was: Theoretical and experimental studies of shock wave interaction with a sphere and a cylinder (Theoretische und experimentelle Untersuchungen zur Beugung von Stosswellen an Kugeln und Zylindern). Dr. Heilig continued this investigation, as well as other related topics, throughout his professional career. His PhD research was co-supervised by Professors Zierep and Oertel and the degree was granted in July 1969. In his dissertation he also discussed the transition criteria from regular to Mach reflection for shock wave reflection from wedges or cylinders (as is evident from Fig. 13 in his dissertation). However, since his results were not published in a reviewed journal, he has not received the credit he duly deserved.After receiving his PhD degree, Dr. Heilig started building his reputation as a careful and reliable researcher in gas dynamics, focusing his attention on shock wave reflection from wedges, shock and blast wave propagation in ducts and tunnels, and shock wave interaction with boundaries of various shapes. Until the mid 1980s most of his work was experimental, that being the strong side of the Ernst-Mach-Institute at the time. In early 1984 Dr. Heilig was assigned to introduce CFD to the Ernst-Mach-Institute. This move forced him to go from being an experimentalist to a CFD researcher, which proved to be very demanding. However, Dr. Heilig did it well, relying on his mathematical skills earned as a student in the 1950s. From the mid 1980s on he was the head of the gas dynamics group at the Ernst-Mach-Institute, and in January 1997 he became the vice-director of the Ernst-Mach-Institute, a position he held until his retirement in February 1998. Once free from formal obligations, he avidly continued his research activities, submitting proposals for (and receiving) research contracts, and writing the chapter on shock wave propagation in ducts and tunnels in the Handbook of Shock Waves which was published in 2000 by Academic Press.I first met Dr. Heilig when he attended the 12th Shock Waves Symposium, which was held in Jerusalem in July 1979, and we kept in touch ever since. We jointly proposed and conducted research on various aspects of shock wave interaction with bodies of numerous shapes, and co-authored several papers based on the results of our joint-research. It was a pleasure working with Dr. Heilig; he was a very careful scientist who was never fazed by challenging problems. His untimely death has shocked and saddened us all. May the emptiness left in our hearts by his departure be filled by gentle memories of Dr. Werner Heilig, an outstanding researcher, colleague and friend.Published online: 18 February 2005[/PUBLISHED]     

Propagation of cylindrical shock waves in a gravitating medium

We study gas motion behind the front of a cylindrical shock wave created by the motion of a piston in a gravitating medium. The problem is self-similar, but the solution cannot be obtained in closed form. A numerical calculation is made for various Mach numbers. The calculation shows that the central part of the configuration is displaced a definite distance from the axis of symmetry.Cylindrical shock waves through a compressible homogeneous medium in a gravity field have been examined by Sedov [1] and Lin [2], However, these studies contain the essential assumption that the total energy (i. e., the sum of the kinetic and thermal energies) within the region bounded by the expanding shock wave is independent of time.In the following we extend the previous studies to the case of shock waves in nonhomogenous media, which propagate in the fluctuating gravity field created by the disturbed mass itself. The shock wave is created by the motion of a piston whose velocity varies as some power of the time, i. e., v. The total energy of the configuration also depends on the time.The authors wish to thank M. P. Murgai for cooperation and assistance and C. D. Ghildyal for valuable advice, as well as L. I. Sedov and G. I. Petrov for their critical comments.     

Shock wave reflection over wedges: a benchmark test for CFD and experiments

In the Shock Wave Journal Vol. 2, No. 4 a benchmark test for shock wave reflection over wedges was announced. International scientists who are interested in shock wave research were invited to participate. The benchmark test aimed at comparison of various advanced numerical schemes as well as experimental results. During the last three years more than twenty results, including both CFD and experiments, were collected from all over the world. Efforts contributed by these scientists made the present benchmark test reach to a standard of the state of the art of the computational fluid dynamics applied to the shock wave research. However, it was regrettable not to publish all the results collected due to limitation on the available page number. Received 5 November 1994 / Accepted 9 September 1996     

Laboratory-scale blast wave phenomena – optical diagnostics and applications

Laboratory-scale experiments with explosive charges in the milligram range are a useful tool to investigate basic blast wave phenomena and to replicate, to some extent, large-scale explosions. This paper reviews and discusses the optical diagnostics that can be applied in these experiments and outlines how these techniques can be used to obtain new information about the propagation and interaction of blast waves. Performance criteria for the required instrumentation are established. Several examples illustrate the potential and the limitations of this approach to blast wave research. PACS 47.40.Nm; 52.35.Tc; 42.40.Kw An abridged version of this paper was presented at the First International Symposium on Interdisciplinary Shock Wave Research in Sendai, Japan, from March 22 to 24, 2004.     

Stability of shock waves with finite relaxation region

A theoretical investigation is made into the amplification of sound in a moving nonequilibrium medium and it is shown that an instability can arise in a sufficiently strong shock wave accompanied by an exothermic process with finite relaxation region, the instability being due to the spontaneous growth of fluctuations resulting from amplification of acoustic waves in the region of exothermic relaxation and their trapping in a narrow layer near the shock wave.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 176–179, September–October, 1982.I thank S. V. Iordanskii for posing the problem and great interest in the work.     

Incidence of plane supersonic jet on a plane at an arbitrary angle

A solution method is described and results are presented of numerical calculations for the problem of determining the subsonic part of the flow with incidence of a plane uniform supersonic jet on a plane at an arbitrary angle, which corresponds to the flow regime with a a detached shock wave. For the problem solution we use the method of integral relations in the first approximation in a polar coordinate system. The calculation results (pressure distribution on the plate, shock wave shape, and velocity gradient magnitude at the stagnation point) are presented for Mach numbers of 5 and 20, in a range of incidence angles from 0° to 35°, and also for M=3 for an incidence angle 0° (angles measured from normal to the plate).In conclusion the authors wish to thank G. I. Taganov for guidance in this work.     

The phenomena of shock wave reflection — a review of unsolved problems and future research needs

Although the phenomenon of shock wave reflection was discovered more than a hundred years ago, active research related to this phenomenon still goes on in many countries in the world (e.g., Australia, Canada, China, Germany, Israel, Japan, Poland, Russia and United States of America). As a matter of fact the research activity increased so drastically in the past decade and a half that a special scientific meeting dedicated to better understanding the reflection phenomena of shock waves, namely The International Mach Reflection Symposium was initiated in 1981 and was held since then in the major research centers actively involved in the research of shock wave reflections. In the present paper the status of the research of the phenomenon of shock wave reflection will be discussed in general, and unresolved problems and future research needs will be pointed out.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.     

Visualization of shock-wave formation processes during shock reflection at obstacles with multiple steps

According to standard textbooks on compressible fluid dynamics, a shock wave is formed by an accumulation of compression waves. However, the process by which an accumulated compression wave grows into a shock wave has never been visualized. In the present paper, the authors tried to visualize this process using a model wedge with multiple steps. This model is useful for generating a series of compression waves and can simulate a compression process that occurs in a shock tube. By estimating the triple-point trajectory angle, we demonstrated visually that an accumulated compression wave grows into a shock wave. Further reflection experiments over a rough-surface wedge confirmed the tendency for the triple point trajectory angle to reach the asymptotic value _s in the end.This work was first presented at the Symposium on Shock Waves, Japan 2002     

Shock tube kinetics in homogeneous and heterogeneous reaction systems

The shock tube used as a high-temperature wave reactor has dominated high-temperature kinetics for more than 45 years. The nearly instantaneous heating to high temperatures, the accessible wide temperature and pressure ranges, and the diffusion-free reaction conditions are the main advantages of this technique for measuring rate co-efficients at high temperatures. In this paper some applications of the shock tube technique for kinetic studies in homogeneous and heterogeneous reaction systems will be discussed. The examples to be presented were obtained in the author's laboratory. They include thermally and photolytically induced chemical reactions, which were studied by applying different optical absorption techniques.An abridged version of this paper was presented as Paul Vieille Memoiral Lecture at the 20th International Symposium on Shock Waves, CALTECH, Pasadena 1995.     

Experimental investigation of the interaction between convergent axisymmetric shock waves and sharp and blunt cones in supersonic flow

The interaction between convergent axisymmetric shock waves and sharp and blunt cones has been experimentally investigated in a wind tunnel at M=4.67. During the experiments the effect of the conicity angle of the convergent shock wave, the shape of the model and its position relative to the shock-wave configuration on the structure of the flow and the pressure distribution on the model surface was explored.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 177–182, September–October, 1991.In conclusion, the author wishes to thank Yu. M. Lipnitskii for formulating the problem and E. N. Bogachev for assistance in organizing the research.     

The reflection of a plane shock wave from a body with groove

When a plane shock wave impinges on bodies with grooves and when a supersonic stream of gas flows past such bodies a complicated flow pattern develops. In a number of cases oscillations of the bow wave [1–3] and an anomalous heating of the gas in the groove [4–6] have been observed. Unsteady reflection of shock waves from bodies with grooves and the processes occurring inside the grooves have been investigated comparatively little.Translated from Izvestiya Akademii Nauk SSSR, Hekhanika Zhidkosti 1 Gaza, No. 5, pp. 180–186, September–October, 1935.The authors wish to thank V. I. Ivanov for carrying out the calculations.     

Nonequilibrium radiation of a strong shock wave

We examine the nonequilibrium radiation from the first negative band of the molecular nitrogen ion N ₂ ⁺ . The various N ₂ ⁺ ion excitation mechanisms are discussed. It is shown that for a shock wave velocity in air 8 km/sec the primary excitation mechanism is electronic impact.In conclusion the authors wish to thank V. K. Vertushkin and A. A. Gladkov for supplying the calculations on the structure of the normal compression shock and L. I. Ponomarev for helpful discussions.     

Motion of shock waves in an inhomogeneous gas

Whitham [1] has proposed a method of approximate calculation of the motion of shock fronts giving results in fairly good agreement with the experiments when one considers various nonstationary problems of the interaction of shock waves with one another and solid surfaces. However, the method gives rise to fundmental difficulties when one considers the propagation of shock waves in a moving medium [1, 2]. In the present paper, the method is generalized to the case of a gas which is moving nonuniformly in front of the shock wave, no restrictions being made on the nature of the motion or the variation of its parameters.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 175–178, January–February, 1981.I thank M. D. Gerasimov for interest and assistance in the work.     

On the center of pressure of conical bodies

The profiles of conical bodies for which the position of the center of pressure in a supersonic flow with symmetry plane does not depend on the flow parameters are considered. The theoretical investigation of the aerodynamic characteristics of circular cones [1] has shown that their center of pressure does not depend on the angle of attack when the shock wave is attached to the apex of the cone. It was established experimentally in [2, 3] for star-shaped bodies that the position of the center of pressure for such bodies hardly changes in a wide range of Mach numbers and angles of attack.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 99–104, January–February, 1980.I thank G. G. Chernyi for discussing the results.     

Plane-parallel supersonic flow with a discontinuity

This article considers a plant-parallel supersonic flow, with a shock wave terminating within the flow; the shock wave is regarded as a distortion. A line of discontinuity is located ahead of the shock wave in the supersonic zone. The problem is solved by the method of indeterminate coefficients.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 95–100, July–August, 1970.The authors thank S. V. Fal'kovich for his valuable advice and for his evaluation of the results obtained.     

On nonlinear oscillations of a thin bar

Summary Based on one of the simplest mathematical model of a solid, nonlinear interactions between waves in a rectilinear bar are investigated, in order to reveal and display a number of dynamic properties inherent not only to the bar, but also to most weakly nonlinear mechanical systems with internal resonances. The presence of internal resonances in the bar is twofold. Firstly, there exists a slow periodic energy exchange between the longitudinal and the two quasi-harmonic bending waves involved in the resonant triad due to the phase matching, secondly, triple-frequency envelope solitons can be created from the resonant triad with the same modal state. The paper investigates the evolution of waves in the bar with the aim to classify the elementary type of wave triplet resonant interactions and define their existence and coesistence areas.The research described here has been made possible in part by Grant N R9B000 from the International Science Foundation. The authors would like to thank Professor G.A. Maugin for having sent copies of his papers, in particular [23], as well as for his permanent interest in our work.     

Effect of electron cyclotron waves on the structure of a weak collisionless shock wave

An analytic study is made of the structure of a weak collisionless shock wave propagating in a magnetized plasma at right angles to the magnetic field. Dissipation is produced by an instability associated with electron cyclotron oscillations.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti 1 Gaza, No. 2, pp. 187–190, March–April, 1982.I thank V. B. Baranov for suggesting the problem and constant interest in the work, and also A. V. Ershov for discussing the results.