A new numerical technique for incompressible flow analyses around high -speed Shinkansen cars entering a tunnel or passing each other and numerical prediction of aerodynamic sound radiated from a circular cylinder are presented. A combined method of the finite element method and the finite difference method is developed for moving boundary problems based on the ABMAC method using a sophisticated time integration scheme and is applied to the aerodynamic analysis around high-speed trains. For aeroacoustic analysis, the large eddy simulation technique is used for the three -dimensional unsteady flow analysis. The far-field sound pressure is then calculated from the fluctuating surface pressure on the cylinder, based on Curie's equation. Computed results for both problems are in good agreements with the experimental results.

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The outline of CP-PACS, a massively parallel computer system (MIMD, distributed memory type) for research of computational physics, is presented. The development of CP-PACS, started in April 1992, aims to achieve more than 600 GFLOPS (peak speed) with 2048 processing units (PU) in 1996. One of the specific PU features of CP-PACS added to usual high-end RISC architecture is to support the PVP-SW (Pseudo Vector Processor based on Slide-Windowed registers). This feature can efficiently hide long memory access latency which comes from high miss-rate of cache on large scale applications. The other specific feature is 3 dimensional Hyper-Crossbar network (HXB). This network connects uniformly all PUs with short diameter, and realize high speed (more than 300 MB/sec) and flexible interconnection. The special high speed message passing protocol enables the system to transfer data more efficiently. The outlines of the support software are also presented.

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Triangulations have been one of main topics in computational geometry and other fields in recent years. In the planar case, any pair of triangulation can be transformed to each other by a sequence of so-called Delaunay flips, and enumeration of all triangulations can be done by reverse search. However, there is no known result for higher-dimensional triangulations. Recently, some types of triangulations have been found to bridge geometric issues and algebraic ones. Regular triangulations are of such a type, and form a meaningful wide subclass of triangulations of points in general dimensions. Especially, regular triangulations have a close connection with discriminants of polynomials in several variables. Restricting ourselves to the class of regular triangulations in any dimensions, we know that such triangulations correspond to vertices of some polytope, and we can enumerate all regular triangulations by reverse search.

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