円柱冷却によって低レイノルズ数で発生する冷却渦列

第3報, 後流パターンに与える流体種類の影響

抄録

Cooled wakes of mercury and water are numerically simulated, and computed results are shown and discussed. As a result, effects of fluid kinds on wake patterns, i.e. the streaklines, streamlines, equi-vorticity lines, and isothermal lines, are elucidated as follows : (1) Effects of the fluid kinds on the cooled wake and the cooled vortex street are extremely strong, because the dominant action is the temperature diffusion in mercury, and the temperature advection in water. (2) The temperature distribution is extremely different between mercury and water. In mercury, the temperature varies in the whole wake, and the isotheral lines draw concentric circles. In water, a number of the temperature islands are generated, and advect heat to the downstream. (3) The cooled vortex street occurs in mercury and water. The shape of the vortex spiral of water is vague and is not circular. The vortex spiral of mercury rotates as a vortex with smooth and clear streaklines. (4) The motions of two separated shear layers of vorticity are extremely different between mercury and water. (5) The Richardson numbers of onsets of the cooled vortex street and symmetric wake in water are extremely larger than those in mercury.