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.

Direct Numerical Simulation of a Fully Developed Turbulent Flow over a Wavy Wall

Abstract: Turbulent flow over a sinusoidal solid wavy surface was investigated by a direct numerical simulation using a spectral element technique. The train of waves has an amplitude to wavelength ratio of 0.05. For the flow conditions (Re=hUb/2ν= 3460) considered, adverse pressure gradients were large enough to cause flow separation. Numerical results compare favorably with those of Hudson's (1993) measurements. Instantaneous flow fields show a large variation of the flow pattern in the spanwise direction in the separated bubble at a given time. A surprising result is the discovery of occasional velocity bursts which originate in the separated region and extend over large distances away from the wavy wall. Turbulence in this region is very different from that near a flat wall in that it is associated with a shear layer which is formed by flow separation.

Numerical solution for the flow around a cylinder at Reynolds numbers of 40, 200 and 500

Abstract: Finite difference solutions for the time dependent equations of motion have been carried out in order to extend the range of available data on steady flow around a cylinder to larger Reynolds numbers. At the termination of the calculations for R = 40 and 200, the separation angle, the drag coefficient and the pressure and vorticity distributions around the surface of the cylinder were very close to their steady-state values. For R = 500 the separation angle and drag coefficient were very close to their steady-state values but the pressure distribution and vorticity distribution at the rear of the cylinder were still changing slightly. The results at R = 500 were found to be quite different from those at R = 200 so it is not clear how closely we approximated the steady solution for R → ∞. The forces on the cylinder due to viscous drag and due to pressure drag are found to be smaller for steady flow than for laboratory experiments where the wake is unsteady.

Rheological phenomena in focus

Abstract: Part 1 Introduction: What is rheology? Why flow visualization? On flow visualization techniques Material functions Dimensionless numbers Outline of the book. Part 2 General Phenomena Rod-climbing Weissenberg effects Post-extrusion effects Extensional viscosity effects Deformation-history effects. Part 3 Contraction and Expansion Flows: Flow through axisymmetric contractions Flow through planar contractions Flow through expansions. Part 4 Confined Flows: Flow over a hole Combined mixing and separating flow Flow in a channel obstructed by an antisymmetric array of obstacles Flow in a "T" geometry Flow past cylinders and sheres High Reynolds number flows Radial flow in a Hele-Shaw cell. Part 5 Rotating and Oscillating Flows Flow in cylindrical containers Flow caused by rotating solids of revolution Instabilities in rotating flows Flow modification in the two-roll mill Flow in the four-roll mill - the Uebler effect Flow generated by a vibrating cylinder. Part 6 Jet Breakup: Deformation and breakup of viscoelastic drops in planar extensional flows Rising bubble in a non-Newtonian liquid Drop entering a liquid Aggregation effects in suspensions of spheres in non-Newtonian liquids.

Miscible displacement in a Hele-Shaw cell at high rates

Abstract: We study experimentally and theoretically the downward vertical displacement of one miscible fluid by another lighter one in the gap of a Hele-Shaw cell at sufficiently high velocities for diffusive effects to be negligible. Under certain conditions on the viscosity ratio, M , and the normalized flow rate, U , this results in the formation of a two-dimensional tongue of the injected fluid, which is symmetric with respect to the midplane. Thresholds in flow rate and viscosity ratio exist above which the two- dimensional flow destabilizes, giving rise to a three-dimensional pattern. We describe in detail the two-dimensional regime using a kinematic wave theory similar to Yang & Yortsos (1997) and we delineate in the ( M , U )-plane three different domains, characterized respectively by the absence of a shock, the presence of an internal shock and the presence of a frontal shock. Theoretical and experimental results are compared and found to be in good agreement for the first two domains, but not for the third domain, where the frontal shock is not of the contact type. An analogous treatment is also applied to the case of axisymmetric displacement in a cylindrical tube.