The Interdisciplinary Shock Wave Research Center does promote the Center of Excellence (COE) research entitled “Investigation of Shock Wave Phenomena in Complex media and Its Interdisciplinary Applications”, which is granted for five years starting from the fiscal year of 2000. The research group consists of scientists of five universities including Tohoku University in the area of physics and medicine. Shock wave phenomena in relatively simple media have been well studied, whereas those in complex media have not yet been understood. The complex media are defined as following: (1) media consisting of complex constituents; (2) shock waves accompanied by chemical reactions or phase changes; (3) three-dimensional shock wave phenomena and those subjected to very complex boundary conditions; and (4) shock wave phenomena with high degree of unsteadiness.

Current status and progress

     The new building of the Interdisciplinary Shock Wave Research Center, about 600 square meters, was completed on March 21, 2001. A large shock tube (14m long, cross section of 100mmÍ180mm, 1m long test section), a two-stage light gas gun (7m long, diameter of 15mm to 51mm, 8km/s maximum speed, recovering tank of 12m long and 1.7m in diameter) and other world leading facilities are employed. The well-developed holographic interferometric technique in this laboratory is implemented with a large Schlieren mirror with 1m diameter, which makes high accurate flow visualization of large scale flow structures possible. Projects that have been completed include the development of 3D simulation using structured and unstructured grids, computer aided image processing, Fourier analysis of finite interferograms, phase-shift holographic interferometry. Many other projects and applications are being under development.     

Sketch of the Interdisciplinary Shock Wave Research Center

Optical Visualization     Holographic interferometry is generally used for flow visualization in this laboratory. With the help of the pulsed ruby laser, not only in shock tube experiment for gases but also liquid and solids, all shock wave phenomena in transparent materials can be visualized. The obtained image information is processed by a fast computer, and flow measurement and analysis can be finished in a short time. Besides holographic interferometry, shadow and schlieren techniques are often used as well. Phase-shift holographic interferometry has been developed for flows with weak density variations. In addition, to visualize high-speed phenomenon in a large view field is being under development.	Explosion of a micro explosive (Taken by the combination of holographic interferometry and color Schlieren method)
Laboratory experiments simulating magma fragmentation in volcanic eruption     Laboratory simulation of magma fragmentation in volcanic eruption is one project being under development among many others. The magma fragmentation is an important process that determines the eruption behavior of a volcano. It is believed that magma fragmentation is generated by rapid decompression of magma that contains bubbles, and grows with the propagation of a front of fragmentation wave. Experiments are conducted using porous viscoelastic fluid filled in a transparent shock tube. For the first time, the generation and propagation of the fragmentation front in the viscoelastic fluid is directly visualized.   Laboratory simulation of the fragmentation of magma in volcano eruption
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