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Hele-Shaw flow (named after Henry Selby Hele-Shaw) is defined as Stokes flow between two parallel flat plates separated by an infinitesimally small gap. Various problems in fluid mechanics can be approximated to Hele-Shaw flows and thus the research of these flows is of importance. Approximation to Hele-Shaw flow is specifically important to micro-flows. This is due to manufacturing techniques, which creates shallow planar configurations, and the typically low Reynolds numbers of micro-flows. The governing equation of Hele-Shaw flows is identical to that of the inviscid potential flow and to the flow of fluid through a porous medium (Darcy's law). It thus permits visualization of this kind of flow in two dimensions. ==Mathematical formulation of Hele-Shaw flows== Let , be the directions parallel to the flat plates, and the perpendicular direction, with being the gap between the plates (at ). When the gap between plates is asymptotically small : the velocity profile in the direction is parabolic (i.e. is a quadratic function of the coordinate in this direction). The equation relating the pressure gradient to the velocity is, : where is the velocity , is the local pressure, is the fluid viscosity. This relation and the uniformity of the pressure in the narrow direction permits us to integrate the velocity with regard to and thus to consider an effective velocity field in only the two dimensions and . When substituting this equation into the continuity equation and integrating over we obtain the governing equation of Hele-Shaw flows, : This equation is supplemented by the no-penetration boundary conditions on the side walls of the geometry, : where is a unit vector perpendicular to the side wall. 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「Hele-Shaw flow」の詳細全文を読む スポンサード リンク
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