Topic
Hele-Shaw flow
About: Hele-Shaw flow is a research topic. Over the lifetime, 5451 publications have been published within this topic receiving 151320 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, cellular secondary flows were artificially generated with alternate rough and smooth bed strips, which were aligned longitudinally in an open channel, and the distributions of the primary velocity and streamwise Reynolds shear stress that are altered in the presence of the secondary flows clearly deviate from those observed for two-dimensional open channel flows.
103 citations
TL;DR: In this article, the linear stability of Hagen-Poiseuille flow with superimposed rigid rotation against small three-dimensional disturbances is examined at finite and infinite axial Reynolds numbers.
Abstract: The linear stability of Hagen-Poiseuille flow (Poiseuille pipe flow) with superimposed rigid rotation against small three-dimensional disturbances is examined at finite and infinite axial Reynolds numbers. The neutral curve, which is obtained by numerical solution of the system of perturbation equations (derived from the Navier-Stokes equations), has been confirmed for finite axial Reynolds numbers by a few simple experiments. The results suggest that, at high axial Reynolds numbers, the amount of rotation required for destabilization could be small enough to have escaped notice in experiments on the transition to turbulence in (nominally) non-rotating pipe flow.
103 citations
TL;DR: To verify the accuracy of the immersed-boundary method proposed in this work, flow problems of different complexity are simulated and the results are in good agreement with the experimental or computational data in previously published literatures.
103 citations
TL;DR: In this paper, the authors consider flow in a Hele- Shaw cell for which the upper plate is being lifted uniformly at a specified rate, which puts the fluid under a lateral straining flow, sucking in the interface and causing it to buckle.
Abstract: We consider flow in a Hele - Shaw cell for which the upper plate is being lifted uniformly at a specified rate. This lifting puts the fluid under a lateral straining flow, sucking in the interface and causing it to buckle. The resulting short-lived patterns can resemble a network of connections with triple junctions. The basic instability - a variant of the Saffman - Taylor instability - is found in a version of the two-dimensional Darcy's law, where the divergence condition is modified to account for the lifting of the plate. For analytic data, we establish the existence, uniqueness and regularity of solutions when the surface tension is zero. We also construct some exact analytic solutions, both with and without surface tension. These solutions illustrate some of the possible behaviours of the system, such as cusp formation and bubble fission. Further, we present the results of numerical simulations of the bubble motion, examining in particular the distinctive pattern formation resulting from the Saffman - Taylor instability, and the effect of surface tension on a bubble evolution that in the absence of surface tension would fission into two bubbles. AMS classification scheme numbers: 76E30, 76D45
103 citations
TL;DR: Qualitative observations are presented which indicate that systolic acceleration may be laminar regardless of the large value of the instantaneous Reynolds number, while diastolic deceleration probably produces disturbed, but not turbulent or highly dissipative, flow.
Abstract: A controlled ex-vivo study of a simple, sinusoidally oscillating flow in a rigid, constant-area, smooth tube, has produced significant insight into the laminar-turbulent transition phenomenon. The development of turbulence was studied by analyzing the dynamic characteristics of the transition process; i.e., the velocity, growth rate, and intermittency which describe the generation and propagation of turbulent slugs. A new concept, the relaxation time, has been introduced to interpret the effect of a periodic flow component superposed on a mean flow. Classical stability concepts, such as the point of inflection criterion and the Reynolds number, which have been derived from steady-flow analysis, are shown to require modification when applied to an oscillatory flow. Neither the mean nor the instantaneous Reynolds number is a sufficient criterion for determining the transition of laminar to turbulent flow in a pulsatile system. Other necessary criteria are: (1) a source of disturbances, (2) the relaxation time, and (3) the distance from the fluid under observation to the source of disturbance. The concept of relaxation time indicates that slowly oscillating flows of large amplitude tend to suppress or destroy turbulence downstream from sources of disturbance. Qualitative observations are presented which indicate that systolic acceleration may be laminar regardless of the large value of the instantaneous Reynolds number, while diastolic deceleration probably produces disturbed, but not turbulent or highly dissipative, flow.
103 citations