水平圆盘耗散的引入(英文)

Dissipation Introduction Through Circular Disc

对于一些特殊的例子,比如说带有月池的圆柱或者很多个圆柱的问题,实验得到的波浪力以及波高不能被传统的势流绕射理论准确地预报,这是由于传统的势流绕射理论忽略了粘性的影响。近些年,为了考虑粘性的影响,提出了两种在势流理论的基础上增加耗散的办法。其中一个是在自由表面增加耗散,另外一个为在流体内部增加耗散。文中采用第二种方法,并且考虑了一个带有月池的圆柱,通过引入一个耗散系数,使得理论的结果和实验的结果得到较好的一致性,同时也说明这种引入耗散的方法是合理的并且可以提供实际的准确的预测。

For some special cases such as cylindrical structure with moon-pool or a group of cylindrical structures, wave loadings associated with wave elevation obtained by model tests can not be well explained by diffraction theory because diffraction theory was limited by ignoring the viscous effect. In order to consider the viscous effect, there are two different ways to introduce the dissipation in the potential flow. One is based on the introduction of a parametric term in the boundary condition on the free-surface which plays a role of extract energy through the free-surface. Second is to introduce a pressure drop through any surface in the fluid and a transparent horizontal surface circular disc of zero thickness dissipation was presented in this paper. Then considering the moon-pool with restricted entrances and introducing this circular disc dissipation in the restricted entrance, the excellent agreement of the free-surface elevation with measurements in model tests is obtained both for the peak period and for the amplitude at resonance by choosing an appropriated dissipation coefficient and also shows that the dissipation through a circular disc is reliable to provide realistic predictions.