scholarly journals Evaluation of the acoustic impedance of a screen

1977 ◽  
Vol 20 (1) ◽  
pp. 46-61 ◽  
Author(s):  
C. Macaskill ◽  
E. O. Tuck
Keyword(s):  
Numerical Computation ◽  
Stokes Flow ◽  
Acoustic Impedance ◽  
Plane Wall ◽  
Regular Array

AbstractA direct numerical computation is provided for the impedance of a screen consisting of a regular array of slits in a plane wall. The problem is solved within the framework of oscillatory Stokes flow, and results presented as a function of porosity, frequency and viscosity.

Stokes flow through periodic orifices in a channel

1994 ◽  
Vol 263 ◽  
pp. 207-226 ◽  
Author(s):  
Y. Zeng ◽  
S. Weinbaum
Keyword(s):  
Aspect Ratio ◽  
Stokes Flow ◽  
Three Dimensional ◽  
Plane Wall ◽  
Channel Height ◽  
Infinite Plane ◽  
Electron Microscopic ◽  
Dimensional Solution ◽  
Aspect Ratios ◽  
Flow Through

This paper develops a three-dimensional infinite series solution for the Stokes flow through a parallel walled channel which is obstructed by a thin planar barrier with periodically spaced rectangular orifices of arbitrary aspect ratio B’/d’ and spacing D’. Here B’ is the half-height of the channel and d’ is the half-width of the orifice. The problem is motivated by recent electron microscopic studies of the intercellular channel between vascular endothelial cells which show a thin junction strand barrier with discontinuities or breaks whose spacing and width vary with the tissue. The solution for this flow is constructed as a superposition of Hasimoto's (1958) general solution for the two-dimensional flow through a periodic slit array in an infinite plane wall and a new three-dimensional solution which corrects for the top and bottom boundaries. In contrast to the well-known solutions of Sampson (1891) and Hasimoto (1958) for the flow through zero-thickness orifices of circular or elliptic cross-section or periodic slits in an infinite plane wall, which exhibit characteristic viscous velocity profiles, the present bounded solutions undergo a fascinating change in behaviour as the aspect ratio B’/d’ of the orifice opening is increased. For B’/d’ [Lt ] 1 and (D’ –- d’)/B’ of O(1) or greater, which represents a narrow channel, the velocity has a minimum at the orifice centreline, rises sharply near the orifice edges and then experiences a boundary-layer-like correction over a thickness of O(B’) to satisfy no-slip conditions. For B’/d’ of O(1) the profiles are similar to those in a rectangular duct with a maximum on the centreline, whereas for B’/d’ [Gt ] 1, which describes widely separated channel walls, the solution approaches Hasimoto's solution for the periodic infinite-slit array. In the limit (D’ –- d’)/B’ [Lt ] 1, where the width of the intervening barriers is small compared with the channel height, the solutions exhibit the same behaviour as Lee & Fung's (1969) solution for the flow past a single cylinder. The drag on the zero-thickness barriers in this case is nearly the same as for the cylinder for all aspect ratios.

Lateral migration of a spherical capsule near a plane wall in Stokes flow

2014 ◽  
Vol 90 (4) ◽  
Author(s):  
S. Nix ◽  
Y. Imai ◽  
D. Matsunaga ◽  
T. Yamaguchi ◽  
T. Ishikawa
Keyword(s):  
Stokes Flow ◽  
Plane Wall ◽  
Lateral Migration ◽  
Spherical Capsule
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