セミナー発足に際してのごあいさつ(1997.4)


第 232 回 Q-NA セミナー
日     時2009 年 3月 18日 (水) 15:30 - 17:00
場     所九州大学箱崎キャンパス 理学部 3号館 3階 3311 号室
講 演 者SHI, Zhong-Ci (Institute of Computational Mathematics, Chinese Academy of Sciences)
題     目Recent progress on wilson nonconforming finite element
概     要Wilson nonconforming finite element (1973) is a very useful rectangular element in practice. It is shown in many engineering applications that the convergence behavior of this element is better than that of the commonly used bilinear element. However, mathematical studies carried out so far cannot justify it. I have spent many years on this problem. The results obtained by use of standard finite element analysis are not satisfactory.
    Recently (2007--) we tackle this problem from a different view point, i.e. from Mechanics, where the Wilson element was originated. We have succeeded in proving both mathematically and numerically that the Wilson element is free of shear locking for a wide class of bending dominated plane elasticity problems, while the bilinear element suffers from shear locking.
    Therefore, we elucidate a long-standing folklore: why Wilson element does a better job in many practical applications than the bilinear element.
備     考水曜日の開催ですのでご注意ください.


第 233 回 Q-NA セミナー
日     時2009 年 3月 30日 (月) 15:30 - 17:00
場     所九州大学箱崎キャンパス 理学部 3号館 3階 3311 号室
講 演 者HUANG, Chieh-Sen (Department of Applied Mathematics, National Sun Yat-sen University)
題     目A fully mass and volume conserving characteristic method and its applications
概     要The characteristics-mixed method considers the transport not of a single point or fluid particle, but rather the mass in an entire region of fluid. This mass is transported along the characteristic curves of the hyperbolic part of the transport equation, and the scheme thereby produces very little numerical dispersion, conserves mass locally, and can use long time steps. However, since the shape of a characteristic trace-back region must be approximated in numerical implementation, its volume may be incorrect, resulting in inaccurate concentration densities and, further, inaccurate reaction dynamics. We present a simple modification to the characteristics-mixed method that conserves both mass and volume of the transported fluid regions. We also present techniques that allow one to conservatively implement wells. Convergence analysis of the scheme is obtained. The techniques are illustrated in miscible and immiscible numerical examples and examples of convection by periodic or cellular flows.
備     考月曜日の開催ですのでご注意ください.

世話人
田上 大助 (九州大学 マス・フォア・インダストリ研究所)
渡部 善隆 (九州大学 情報基盤研究開発センター)

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