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In differential calculus, the Reynolds transport theorem (also known as the Leibniz–Reynolds transport theorem), or in short Reynolds' theorem, is a three-dimensional generalization of the Leibniz integral rule which is also known as differentiation under the integral sign. The theorem is named after Osborne Reynolds (1842–1912). It is used to recast derivatives of integrated quantities and is useful in formulating the basic equations of continuum mechanics. Consider integrating over the time-dependent region that has boundary , then taking the derivative with respect to time: : If we wish to move the derivative within the integral, there are two issues: the time dependence of , and the introduction of and removal of space from due to its dynamic boundary. Reynolds' transport theorem provides the necessary framework. == General form == Reynolds' transport theorem, derived in,〔L. G. Leal, 2007, p. 23.〕〔O. Reynolds, 1903, Vol. 3, p. 12–13〕〔J.E. Marsden and A. Tromba, 5th ed. 2003〕 is: : in which is the outward-pointing unit-normal, is a point in the region and is the variable of integration, and are volume and surface elements at , and is the velocity of the area element – so not necessarily the flow velocity.〔Only for a material element there is 〕 The function may be tensor, vector or scalar valued.〔H. Yamaguchi, ''Engineering Fluid Mechanics, ''Springer c2008 p23〕 Note that the integral on the left hand side is a function solely of time, and so the total derivative has been used. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Reynolds transport theorem」の詳細全文を読む スポンサード リンク
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