Three-dimensional centrifugal-flow instabilities in the lid-driven-cavity problem

Abstract

The classical rectangular lid-driven-cavity problem is considered in which the motion of an incompressible fluid is induced by a single lid moving tangentially to itself with constant velocity. In a system infinitely extended in the spanwise direction the flow is two-dimensional for small Reynolds numbers. By a linear stability analysis it is shown that this basic flow becomes unstable at higher Reynolds numbers to four different three-dimensional modes depending on the aspect ratio of the cavity’s cross section. For shallow cavities the most dangerous modes are a pair of three-dimensional short waves propagating spanwise in the direction perpendicular to the basic flow. The mode is localized on the strong basic-state eddy that is created at the downstream end of the moving lid when the Reynolds number is increased. In the limit of a vanishing layer depth the critical Reynolds number approaches a finite asymptotic value. When the depth of the cavity is comparable to its width, two different centrifugal-instability modes can appear depending on the exact value of the aspect ratio. One of these modes is stationary, the other one is oscillatory. For unit aspect ratio (square cavity), the critical mode is stationary and has a very short wavelength. Experiments for the square cavity with a large span confirm this instability. It is argued that this three-dimensional mode has not been observed in all previous experiments, because the instability is suppressed by side-wall effects in small-span cavities. For large aspect ratios, i.e., for deep cavities, the critical three-dimensional mode is stationary with a long wavelength. The critical Reynolds number approaches a finite asymptotic value in the limit of an infinitely deep cavity.

Biomimetic cilia arrays generate simultaneous pumping and mixing regimes

“…The flow profile has been shown to be approximately constant over much of the width of the cavity in the direction perpendicular to the vortical flow (44). In a low aspect-ratio cavity (w > h), the velocity profile near the center of the cavity is Poiseuille-Couette flow (37,45). Our velocity profile was measured near the center of the array, several hundreds of microns from any lateral boundaries.…”

The linearized pressure Poisson equation for global instability analysis of incompressible flows

“…Solutions to the real BiGlobal EVP which can be derived from (2-5) using a simple transformation [60] have been obtained subject to the two-dimensional LPPE boundary closure (12) in a spanwise homogeneous square lid-driven cavity [4,58]. On the other hand, flow driven by a constant pressure gradient in a duct of square cross-section [54,63] is an example of wall-bounded flow, instability of which is governed by a complex (two-dimensional) BiGlobal EVP.…”

Influence of Gas and Liquid Viscosity on Turbine and Positive Displacement Meters Calibration

“…Density and dynamic viscosity of liquid samples were measured using the meter SVM 3000 at temperatures measured during the experiment. Density measurement uncertainty was 0.0005 g/cm 3 , viscosity was 0.35%. Best volume measurement capability using volumetric measurement method, taking into account liquid flow rate, varied within range from 0.060 % to 0.065 %.…”

“…Usually at low Re, large scale and low frequency structures accumulating the biggest part of the flow energy are observed. With Re increase, high frequency pulsations indicating the occurrence of thinner (smaller) structures are more vivid [3,4]. Centrifugal forces enable the formation of 3D instabilities.…”