Cavitation in an orifice flow

Dabiri, Sadegh; Sirignano, William A.; Joseph, Daniel D.

doi:10.1063/1.2750655

Cited by 58 publications

(30 citation statements)

References 23 publications

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“…with Q ¼ 2g (9) shows that e t uðgÞ ¼ g=d, i.e., uðgÞ ¼ g, which contradicts our requirements du=dg jg¼0 ¼ 0, derived from condition equation (7). Indeed, thermodynamic equilibrium conditions @U=@g ¼ 0 and e 0 ¼ À@U=@p result in…”

Section: Comparison With Alternative Phase-field Approaches a Comentioning

confidence: 45%

Phase-field modeling of fracture in liquid

Levitas

Idesman

Palakala

2011

Journal of Applied Physics

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Phase-field theory for the description of the overdriven fracture in liquid (cavitation) in tensile pressure wave is developed. Various results from solid mechanics are transferred into mechanics of fluids. Thermodynamic potential is formulated that describes the desired tensile pressure-volumetric strain curve and for which the infinitesimal damage produces infinitesimal change in the equilibrium bulk modulus. It is shown that the gradient of the order parameter should not be included in the energy, in contrast to all known phase-field approaches for any material instability. Analytical analysis of the equations is performed. Problems relevant to the melt-dispersion mechanism of the reaction of nanoparticles on cavitation in spherical and ellipsoidal nanoparticles with different aspect ratios, after compressive pressure at its surface sharply dropped, are solved using finite element method. Some nontrivial features (lack of fracture at dynamic pressure much larger than the liquid strength and lack of localized damage for some cases) are obtained analytically and numerically. Equations are formulated for fracture in viscous liquid. A similar approach can be applied to fracture in amorphous and crystalline solids. Phase-field theory for the description of the overdriven fracture in liquid (cavitation) in tensile pressure wave is developed. Various results from solid mechanics are transferred into mechanics of fluids. Thermodynamic potential is formulated that describes the desired tensile pressure-volumetric strain curve and for which the infinitesimal damage produces infinitesimal change in the equilibrium bulk modulus. It is shown that the gradient of the order parameter should not be included in the energy, in contrast to all known phase-field approaches for any material instability. Analytical analysis of the equations is performed. Problems relevant to the melt-dispersion mechanism of the reaction of nanoparticles on cavitation in spherical and ellipsoidal nanoparticles with different aspect ratios, after compressive pressure at its surface sharply dropped, are solved using finite element method. Some nontrivial features (lack of fracture at dynamic pressure much larger than the liquid strength and lack of localized damage for some cases) are obtained analytically and numerically. Equations are formulated for fracture in viscous liquid. A similar approach can be applied to fracture in amorphous and crystalline solids.

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Section: Comparison With Alternative Phase-field Approaches a Comentioning

confidence: 45%

Phase-field modeling of fracture in liquid

Levitas

Idesman

Palakala

2011

Journal of Applied Physics

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“…For detailed descriptions for this interface tracking see Dabiri, Sirignano & Joseph (2007, 2008 and Dabiri (2009). The computational domain consists of a Cartesian grid.…”

Section: Computational Methods and 3-d Liquid-segment Modelmentioning

confidence: 99%

Early spray development at high gas density: hole, ligament and bridge formations

et al. 2016

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Three-dimensional temporal instabilities, leading to spray formation of a round liquid jet segment with an outer, coaxial high-density gas flow, are studied with Navier-Stokes and level-set computations. These computations predict the liquid surface shape showing the smaller structures on the conical wave crests, i.e. lobes, holes, bridges and ligaments, which are the precursors to droplet and spray formations. These structures and their time scales affect droplet size and velocity distributions as well as spray cone angles. The gas-to-liquid density ratio, liquid Reynolds number (Re) and liquid Weber number (We) range between 0.02-0.9, 320-16 000 and 2000-230 000, respectively, which cover three distinct physical domains. (1) At higher Re and We, ligaments and then drops develop following hole and liquid bridge formations. (2) At higher gas densities throughout the Re range, several holes merge forming two bridges per lobe before breaking to form ligaments; this hole merging is explained by slower development of hairpin vortices and lobe shape. (3) In cases where both gas density and Re or We are lower, the well-ordered lobes are replaced by more irregular, smaller-scale corrugations along the conical wave crest edge; ligaments form differently by stretching from the lobes before holes form. Thicker ligaments and larger droplets form in the low Re, low gas density range. The surface wave dynamics, vortex dynamics and their interactions are explained. Understandings of liquid stream break up and concurrent smaller structure formation are built upon an examination of both translation and rotation of the fluid. In all cases, hole formation is correlated with hairpin and helical vortices; fluid motion through a perforation in the thin sheet near the wave crest corresponds to these vortices. The hole formation process is dominated by inertial forces rather than capillary action, which differs from mechanisms suggested previously for other configurations. Circulation due to streamwise vorticity increases while the lobes thin and holes form. For larger surface tension, cavities in the jet core rather than perforations in a sheet occur. The more rapid radial extension of the two-phase mixture with increasing gas density is explained by greater circulation in the ring (i.e. wave crest) region. Experimental descriptions of the smaller structures are available only at lower Re and lower density, † Email address for correspondence: sirignan@uci.edu Hole, ligament and bridge formations 187 agreeing with the computations. Computed scales of bridges, ligaments, early droplets and emerging spray radii agree qualitatively with experimental evidence through the high Re and We domains.

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“…The temporal deformation of the liquid-gas interface is predicted, resulting in three-dimensional instabilities, that can lead to ligament formation and sheet breakup. The original code containing the LS subroutines was developed and applied by Dabiri et al (2007), and later by Jarrahbashi & Sirignano (2014), Jarrahbashi et al (2016), and Zandian et al (2016). Because of the weakness of the level-set method in mass conservation at low density ratios, the VoF method is used at low gas densities.…”

Section: Methodsmentioning

confidence: 99%

Understanding liquid-jet atomization cascades via vortex dynamics

2018

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Temporal instabilities of a planar liquid jet are studied using direct numerical simulation (DNS) of the incompressible Navier-Stokes equations with level-set (LS) and volume-offluid (VoF) surface tracking methods. λ 2 contours are used to relate the vortex dynamics to the surface dynamics at different stages of the jet breakup, namely, lobe formation, lobe perforation, ligament formation, stretching, and tearing. Three distinct breakup mechanisms are identified in the primary breakup, which are well categorized on the parameter space of gas Weber number (W e g ) versus liquid Reynolds number (Re l ). These mechanisms are analyzed here from a vortex dynamics perspective. Vortex dynamics explains the hairpin formation, and the interaction between the hairpins and the Kelvin-Helmholtz (KH) roller explains the perforation of the lobes, which is attributed to the streamwise overlapping of two oppositely-oriented hairpin vortices on top and bottom of the lobe. The formation of corrugations on the lobe front edge at high Re l is also related to the location and structure of the hairpins with respect to the KH vortex. The lobe perforation and corrugation formation are inhibited at low Re l and low W e g due to the high surface tension and viscous forces, which damp the small scale corrugations and resist hole formation. Streamwise vorticity generation -resulting in three-dimensional instabilities -is mainly caused by vortex stretching and baroclinic torque at high and low density ratios, respectively. Generation of streamwise vortices and their interaction with spanwise vortices produce the liquid structures seen at various flow conditions. Understanding the liquid sheet breakup and the related vortex dynamics are crucial for controlling the droplet size distribution in primary atomization.

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Cavitation in an orifice flow

Cited by 58 publications

References 23 publications

Phase-field modeling of fracture in liquid

Phase-field modeling of fracture in liquid

Early spray development at high gas density: hole, ligament and bridge formations

Understanding liquid-jet atomization cascades via vortex dynamics

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