Kinetic energy spectra and flux in turbulent phase-separating symmetric binary-fluid mixtures

We conduct direct numerical simulations (DNS) of the Cahn–Hilliard–Navier–Stokes (CHNS) equations to investigate the statistical properties of a turbulent phase-separating symmetric binary-fluid mixture. Turbulence causes an arrest of the phase separation which leads to the formation of a statistically steady emulsion. We characterise turbulent velocity fluctuations in an emulsion for different values of the Reynolds number and the Weber number. Our scale-by-scale kinetic energy budget analysis shows that the interfacial terms in the CHNS equations provide an alternative route for the kinetic energy transfer. By studying the probability distribution function (p.d.f.) of the energy dissipation rate, the vorticity magnitude and the joint-p.d.f. of the velocity-gradient invariants we show that the statistics of the turbulent fluctuations do not change with the Weber number.

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Binary Fluid Mixture and Thermocapillary Effects on the Wetting Characteristics of a Heated Curved Meniscus

Journal of Heat Transfer ◽

10.1115/1.1599372 ◽

2003 ◽

Vol 125 (5) ◽

pp. 867-874 ◽

Cited By ~ 19

Author(s):

David M. Pratt ◽

Kenneth D. Kihm

Keyword(s):

Pore System ◽

Concentration Gradients ◽

Fluid Mixture ◽

Binary Fluid ◽

Fluid Mixtures ◽

Naturally Occurring ◽

Theoretical Predictions ◽

Interfacial Temperature ◽

Binary Fluid Mixtures ◽

Liquid Vapor

An investigation has been conducted into the interactions of binary fluid mixtures (pentane [C5H12] coolant and decane [C10H22] additive) and thermocapillary effects on a heated, evaporating meniscus formed in a vertical capillary pore system. The experimental results show that adding decane, the secondary fluid that creates the concentration gradient, actually decreases the meniscus height to a certain level, but did increase the sustainable temperature gradient for the liquid-vapor interface, so did the heat transfer rate, delaying the onset of meniscus instability. The results have demonstrated that interfacial thermocapillary stresses arising from liquid-vapor interfacial temperature gradients, which is known to degrade the ability of the liquid to wet the pore, can be counteracted by introducing naturally occurring concentration gradients associated with distillation in binary fluid mixtures. Also theoretical predictions are presented to determine the magnitudes of both the thermocapillary stresses and the distillation-driven capillary stresses, and to estimate the concentration gradients established as a result of the distillation in the heated pore.

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Binary Fluid Mixture and Thermocapillary Effects on the Wetting Characteristics of a Heated Curved Meniscus

10.1115/imece2000-1429 ◽

2000 ◽

Author(s):

David M. Pratt ◽

Kenneth D. Kihm

Keyword(s):

Transport Capacity ◽

Pore System ◽

Concentration Gradients ◽

Fluid Mixture ◽

Binary Fluid ◽

Fluid Mixtures ◽

Naturally Occurring ◽

Interfacial Temperature ◽

Binary Fluid Mixtures ◽

Capillary Pore

Abstract An investigation of the thermocapillary effects on a heated, evaporating meniscus formed by binary fluid mixtures of wetting liquids in a vertical capillary pore system has been conducted. Experiments were conducted to primarily observe the wetting characteristics of the binary fluid mixture and how they are affected by the dynamics associated with the heating of and evaporation from a meniscus. The results have demonstrated that interfacial thermocapillary stresses arising from liquid-vapor interfacial temperature gradients that degrade the ability of the liquid to wet the pore can be counteracted by introducing naturally occurring concentration gradients associated with distillation in binary fluid mixtures without affecting the heat transport capacity of the system.

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