第82回流体懇話会のご案内
平成14年12月9日
流体懇話会の講演会を下記のように開催いたします。どうぞご参加下さい。
今回の会場は電気通信大学 東４号館8階AV会議室(いつもどおり)です。
講師：柳瀬 眞一郎 (岡大・工)
演題：回転乱流中の渦構造を生成する正のフィードバック機構
内容：The vortical structures in a uniformly sheared turbulent flow in
a rotating co-ordinate system are investigated theoretically based on
direct numerical simulation data. Generation and sustenance mechanisms
of long-lived longitudinal tubular vortical structures are examined in
the zero-absolute-vorticity system. It is found that they are born
from random fluctuating vorticity under the effect of the Coriolis
force and grow in the form of vortex layer with their axial vorticity
tilted toward the background shear vorticity. As time goes on, the
vortex layers change to tube structures and develop under combined
effects of the Coriolis force and a swirling motion of the tubular
vortex itself, which constitutes a positive feedback mechanism not
existing in non-rotating shear flow turbulence. In this process, a
finite-angle deviation of vortical structures from the streamwise
direction is an important factor to maintain the structure. It is
frequently observed that tubular vortices change their direction of
axial vorticity toward the system rotation. These whole processes are
not caused merely by the linear shear-Coriolis instability but by an
essentially nonlinear mechanism though an initial growth is partly
related to the linear instability. Vortex tube formation from vortex
layer in an earlier period as well as the longevity of the longitudinal
vortical structures observed in a later period indicates that little
deformation effect of tubular vortex exists in the zero-absolute-
vorticity system.
日時： 平成14年12月20日(金) １６：３０〜１８：００
場所： 電気通信大学 東4号館8階AV会議室
流体懇話会事務局
（電気通信大学）
TEL:0424-43-5438
FAX:0424-88-6371
e-mail：naoya@miyazaki.mce.uec.ac.jp
流体懇話会のお知らせ
連絡は懇話会事務局(naoya@miyazaki.mce.uec.ac.jp) まで
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