By applying the theory of random walk to a turbulent flow, the frequency distribution functions of wind speed and wind direction are derived. The turbulence in the flow is assumed to be homogeneous and isotropic in the horizontal, and further the phase angles of each component of the Fourier series of the finite variable wind speed are assumed to be at random and independent of each other. Further by using the frequency distribution functions of wind speed, the diffusivity in the horizontal is obtained. Because there is no conclusive Lagrangian correlation function, we discussed the diffusivity using some correlation functions.The theory is tested by using the records obtained in the

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Recently, the development of computer technologies has been rapid and they have been applied in numerous fields. In graph drawing, for example, a picture composed of points and lines is used to represent a graph. In general, graph drawing results are evaluated in terms of ease of viewing. However, such evaluations are strongly dependent on individual taste and therefore are not yet fully satisfactory. In this paper, as a step toward the creation of a general standard of “ease of viewing,” we present a quantitative method of evaluating graph drawing performance. Two algorithms based on the spring model are quantitatively evaluated using drawn objects and revised versions of the algorithms are developed. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 3, 80(6): 54–61, 1997

Experimental and numerical studies were made to investigate the effects of wavy interface on the liquid film to gas-phase turbulence modification of air-water annular flow in a vertically arranged round tube. By using the constant temperature hotwire anemometer, time-averaged axial velocity profiles, turbulence fluctuation profiles, energy spectrum and auto-correlation coefficient for fluctuation velocity component of gas-phase axial velocity were precisely measured. The liquid film thickness was also measured by using point-electrode resistivity probe to make clear the time-averaged liquid film thickness and wave height moving on the liquid film. Direct observations using high speed video camera were also added to make clear the dynamic behavior and propergating velocity of ripple or disturbance waves on liquid film flow. Numerical simulations for gas-phase turbulence in annular flow considering the effect of wavy interface of liquid film flow were also carried out. Liquid film flow was modeled to be the wall surface roughness of interfacial wave height moving with the interfacial velocity. The roughness and moving velocity of the modeled liquid film for computational condition were provided by the present experimental results. Time-averaged velocity profiles and fluctuation velocity profiles were calculated with standard k-ε model. Numerical results were generally consistent with the experimental results obtained in the present study.

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