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.
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TL;DR: In this article, a detailed analysis of the flow over smoothly contoured constrictions in a plane channel is presented, which is a generic case of a flow separating from a curved surface with well-defined flow conditions.
292 citations
TL;DR: In this paper, the authors investigated the effect of separation bubble formation and boundary layer separation on coherent structures in low Reynolds number flows and showed that roll-up vortices formed in the separated shear layer due to the amplification of natural disturbances, and these structures played a key role in flow transition to turbulence.
Abstract: Development of coherent structures in the separated shear layer and wake of an airfoil in low-Reynolds-number flows was studied experimentally for a range of airfoil chord Reynolds numbers, 55 × 10 3 ≤ Re c ≤ 210 × 10 3 , and three angles of attack, α = 0°, 5° and 10°. To illustrate the effect of separated shear layer development on the characteristics of coherent structures, experiments were conducted for two flow regimes common to airfoil operation at low Reynolds numbers: (i) boundary layer separation without reattachment and (ii) separation bubble formation. The results demonstrate that roll-up vortices form in the separated shear layer due to the amplification of natural disturbances, and these structures play a key role in flow transition to turbulence. The final stage of transition in the separated shear layer, associated with the growth of a sub-harmonic component of fundamental disturbances, is linked to the merging of the roll-up vortices. Turbulent wake vortex shedding is shown to occur for both flow regimes investigated. Each of the two flow regimes produces distinctly different characteristics of the roll-up and wake vortices. The study focuses on frequency scaling of the investigated coherent structures and the effect of flow regime on the frequency scaling. Analysis of the results and available data from previous experiments shows that the fundamental frequency of the shear layer vortices exhibits a power law dependency on the Reynolds number for both flow regimes. In contrast, the wake vortex shedding frequency is shown to vary linearly with the Reynolds number. An alternative frequency scaling is proposed, which results in a good collapse of experimental data across the investigated range of Reynolds numbers.
281 citations
TL;DR: This method combines the advantage of the two approaches and gives a second-order Eulerian discretization for interface problems and is applied to Hele?Shaw flow, an unstable flow involving two fluids with very different viscosity.
279 citations
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21 Jun 2004TL;DR: In this paper, the authors present a general nomenclature of streamwise vorticity and three-dimensional flow in fluid components, including boundary layers, free shear layers, and flow with heat addition.
Abstract: Preface Acknowledgements Conventions and nomenclature 1. Equations of motion 2. Some useful basic ideas 3. Vorticity and circulation 4. Boundary layers and free shear layers 5. Loss sources and loss accounting 6. Unsteady flow 7. Flow in rotating passages 8. Swirling flow 9. Generation of streamwise vorticity and three-dimensional flow 10. Compressible internal flow 11. Flow with heat addition 12. Non-uniform flow in fluid components References Supplementary references appearing in figures Index.
274 citations
TL;DR: This work experimentally evidence a transition between situations where the flow takes the form of a jet and regimes where drops are produced, within a simple linear analysis using lubrication theory for flows at low Reynolds number, and reaches remarkable agreement with the data.
Abstract: Motivated by its importance for microfluidic applications, we study the stability of jets formed by pressure-driven concentric biphasic flows in cylindrical capillaries. The specificity of this variant of the classical Rayleigh-Plateau instability is the role of the geometry which imposes confinement and Poiseuille flow profiles. We experimentally evidence a transition between situations where the flow takes the form of a jet and regimes where drops are produced. We describe this as the transition from convective to absolute instability, within a simple linear analysis using lubrication theory for flows at low Reynolds number, and reach remarkable agreement with the data.
270 citations