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The aerodynamic characteristic parameters are the foundation of vibration analysis of the overhead conductors. In this paper, a typical overhead conductor is studied using computational fluid dynamics (CFD) method. The smooth wire model and rough wire model are established, respectively, and the experimental analysis is carried out in the numerical wind tunnel. The aerodynamic parameters are obtained, and the influence of roughness of the wire surface is investigated.

For the limitations of the research methods, emphasis has always been put on the dynamics of the bridge sections with no concern about the flow structure around the decks, when carrying the research of the mechanism of wind-induced vibrations. The emergence of PIV (particle image velocimetry) makes it possible to analyze the flow structures. In order to inspect the relationship between the dynamics of decks and the flow structures around the decks, the static force coefficients of the bridge slotted decks and the velocity maps are marked and analyzed using numerical wind tunnel tests. Snapshot POD method is carried out to analyze the flow structures around the decks to find the dominant vortices in the flow filed. The fluctuating velocity maps are reconstructed using the first several modes with most of the energy contained. The research shows that in the flow field around the decks there are some periodic moving vortices. Relationship is found between the rule of the kinemics of the vortices and the static force coefficients of the decks. The research in this paper will guarantee the theoretical basis for investigating the micro mechanism of wind induced vibrations of bridges using the method of PIV.

HOPE-X (H-II Orbiting Plane Experiment) is scheduled for launch in the first decade of 21st century. For several years, systematic aerodynamic study has been conducted by the wind tunnel tests and CFD simulât ions [1]. Recently, in order to reduce vehicle weight and get high performance, configuration of HOPE-X is re-designed from tip-fin type to two-vertical fin type geometry. For this new aerodynamic configuration design, CFD has been mainly used and Navier-Stokes calculations have been performed from low(M∞ = 0.4) to hypersonic speed (M∞ = 26), using NAL NWT (Numerical Wind Tunnel) system[2]. Through these effort of the parametric CFD study, new basic design configuration, HOPE 11 model, is determined. In the present study, this redesigned HOPE 11 aerodynamic characteristics are further investigated in detail from launching to re-entry phase along its flight trajectory. Comparisons with wind tunnel tests are also made.

NAL(National Aerospace Laboratory) is developing a common parallel CFD Platform UPACS(Unified Platform for Aerospace Computational Simulation), for the purpose of the efficient CFD programming and the aggregation of the CFD technology of NAL. UPACS is coded based on three-dimensional Navier-Stokes equations and supports multi-block grids. It is parallelized by MPI message passing library. In this paper the concept and the structure of UPACS is described and its computational performance is evaluated on NAL NWT(Numerical Wind Tunnel) supercomputer.

A practical three-dimensional shape optimization for aerodynamic design of a transonic wing has been performed using Evolutionary Algorithms (EAs). Because EAs coupled with aerodynamic function evaluations require enormous computational time, Numerical Wind Tunnel (NWT) located at National Aerospace Laboratory in Japan has been utilized based on the simple master-slave concept. Parallel processing makes EAs a very promising approach for practical aerodynamic design.

Direct numerical simulation(DNS) of fundamental fluid flow simulation using 3-dimensional Navier-Stokes equations is a typical large scale computing which requires high performance computer with vector and parallel processing. In the present paper a turbulent boundary layer flow simulation with strong adverse pressure gradient on a flat plate was made on NAL Numerical Wind Tunnel. Boundary layer subjected to a strong adverse pressure gradient creates a separation bubble followed by a region with small, but positive, skin friction. This flow case contains features that has proven to be difficult to predict with existing turbulence models. The data from present simulation are used for investigation of the scalings near the wall, a crucial concept with respect to turbulence models. The present analysis uses spectral methods and the parallelization was done using MPI(Message-Passing Interface). A good efficiency was obtained in NWT. To compare with other machine performances, previous computations on T3E and SP2 are also shown.

An accurate and convenient numerical simulations are essentially needed for the complex and unknown (natural) phenomena or the engineering design problems. This simulation methodology is called the computational mechanics in the field of the computational engineering technology. The present simulation methodology, however, have been generated by using the procedure type programming techinique. Therefore, the accurate simulations for the complex and unknown phenomena have not suffisiently be realized, and the flexibility of the simulation system is not at all sufficient.