Mixing, Diffusion and Chemical Reaction of Liquids in a Vortex Field

Marble, Frank E.

doi:10.1007/978-1-4613-1023-5_51

Cited by 18 publications

(13 citation statements)

References 6 publications

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“…The convection-diffusion transport equation for C reduces (see e.g. Levque 1928; Mohr, Saxton & Jepson 1957;Marble & Broadwell 1977;Ranz 1979;Rhines & Young 1983;Allgre & Turcotte 1986;Marble 1988;Ottino 1989;Beigie, Leonard & Wiggins 1991;Meunier & Villermaux 2003;Fannjiang et al 2004) to a one-dimensional problem when the radius of curvature of the iso-concentration surface is large compared to the lamella thickness (Dimotakis & Catrakis 1999). Let s(t) be the distance between two material particles in the direction z perpendicular to a sheet and…”

Section: Appendix a Stretching Enhanced Diffusionmentioning

confidence: 99%

Mixing by random stirring in confined mixtures

2008

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International audienceWe study the relaxation of initially segregated scalar mixtures in randomly stirred media, aiming to describe the overall concentration distribution of the mixture, its shape and rate of deformation as it evolves towards uniformity. A stirred scalar mixture can be viewed as a collection of stretched sheets, possibly interacting with each other. We consider a situation in which the interaction between the sheets is enforced by confinement and is the key factor ruling its evolution. It consists of following a mixture relaxing towards uniformity around a fixed average concentration while flowing along a constant cross-section channel. The interaction between the sheets is found to be of a random addition nature in concentration space, leading to concentration distributions that are stable by self-convolution. The resulting scalar field is naturally coarsened at a scale much larger than the dissipation scale. Consequences on the mixture entropy and scalar rate of dissipation are also examined

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Section: Appendix a Stretching Enhanced Diffusionmentioning

confidence: 99%

Mixing by random stirring in confined mixtures

2008

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“…The degree of molecular mixing within a flowfield may be quantified using the concept of mixedness 35,36 as well as the concept of unmixedness. 37,38 Both concepts quantify mixing in terms of the second moment of the scalar concentration field, enabling comparisons of the local scalar field to be made with the scalar field that would be present if the fluids were completely mixed or completely unmixed.…”

Section: ͑2͒mentioning

confidence: 99%

Mixing enhancement in a lobed injector

et al. 1997

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A study on a lobed jet mixing flow by using stereoscopic particle image velocimetry technique An experimental investigation of the non-reactive mixing processes associated with a lobed fuel injector in a coflowing air stream is presented. The lobed fuel injector is a device which generates streamwise vorticity, producing high strain rates which can enhance the mixing of reactants while delaying ignition in a controlled manner. The lobed injectors examined in the present study consist of two corrugated plates between which a fuel surrogate, CO 2 , is injected into coflowing air. Acetone is seeded in the CO 2 supply as a fuel marker. Comparison of two alternative lobed injector geometries is made with a straight fuel injector to determine net differences in mixing and strain fields due to streamwise vorticity generation. Planar laser-induced fluorescence ͑PLIF͒ of the seeded acetone yields two-dimensional images of the scalar concentration field at various downstream locations, from which local mixing and scalar dissipation rates are computed. It is found that the lobed injector geometry can enhance molecular mixing and create a highly strained flowfield, and that the strain rates generated by scalar energy dissipation can potentially delay ignition in a reacting flowfield.

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“…The reactive transport equations (Eqs. (5) and (6)) were solved using the quasi-steady-state velocity fields calculated above. The lateral boundary conditions were no-flux n · (−D∇C + uC) = 0, and the outlet boundary had the convective flux condition n · (−D∇C) = 0.…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…The laminar cylinder wake is a well-studied system that is useful for our purposes in that it enables us to extend previous work involving a single vortex to a system of interacting vortices shed behind the cylinder. 4 Previous investigations of mixing and reactions in in flows consisting of either a single vortex [5][6][7][8] or a vortex pair 9, 10 elucidate many of the process-level details of how vortical flows enhance mixing and reactions.…”

Section: Introductionmentioning

confidence: 99%

Reaction of initially distant scalars in a cylinder wake

Crimaldi

Kawakami

2013

Physics of Fluids

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Articles you may be interested inOn oblique and parallel shedding behind an inclined plate Phys. Fluids 25, 054101 (2013); 10.1063/1.4802046 A numerical study of the laminar necklace vortex system and its effect on the wake for a circular cylinder Phys. Fluids 24, 073602 (2012); 10.1063/1.4731291 Low Reynolds number flow over a square cylinder with a splitter plateWe used analytical and numerical techniques to investigate the effect of a quasisteady-state laminar wake behind a circular cylinder on the second-order reaction between two initially distant scalars. The scalars are released continuously from locations upstream of the cylinder, and are separated from each other by a lateral distance that initially impedes the reaction. By comparing the laterally integrated reaction evolution for cases with and without the cylinder wake, the direct effect of the wake on reaction enhancement is determined. We compute the reaction for a range of reaction speeds, scalar diffusivities, and scalar release geometries. The presence of the cylinder wake generates significant reaction enhancement for all cases; the ratio of the reaction with and without the cylinder increases with the initial scalar separation distance. We identify the mechanism for the reaction enhancement, and demonstrate that the reaction rate in the cylinder wake can be predicted by a simple analytical model of a stretched scalar interface. C 2013 AIP Publishing LLC.

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Mixing, Diffusion and Chemical Reaction of Liquids in a Vortex Field

Cited by 18 publications

References 6 publications

Mixing by random stirring in confined mixtures

Mixing by random stirring in confined mixtures

Mixing enhancement in a lobed injector

Reaction of initially distant scalars in a cylinder wake

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