Direct numerical simulation of a liquid sheet in a compressible gas stream in axisymmetric and planar configurations

Siamas, George A.; Jiang, Xi

doi:10.1007/s00162-007-0051-4

Cited by 8 publications

(4 citation statements)

References 36 publications

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“…Klein 26 performed DNS of a liquid sheet exhausting into a gaseous incompressible atmosphere under moderate Reynolds number. Direct computations of two-phase gas-liquid flows have been performed in axisymmetric and planar configurations [27][28][29] and good agreement with linear theories has been obtained. An extended study in full three dimensions is needed for detailed realization of the mixing.…”

Section: Introductionmentioning

confidence: 81%

“…In this study, the original VOF method has been adapted to solve an equation for the liquid mass fraction Y rather than the volume fraction ⌽ in order to suit the compressible gas phase formulation. [27][28][29] From their definitions, a relation between liquid volume fraction and liquid mass fraction can be derived as…”

Section: Governing Equationsmentioning

confidence: 99%

“…The 3D parallel DNS code used was developed from the 3D parallel DNS code for gas jets 48,49 based on the gas-liquid two-phase flow formulation used in the axisymmetric and planar simulations. [27][28][29] The excessive computational cost needed to perform the complex two-phase DNS ͑around 300 000 allocation units on HPCx per simulation͒ limits the computation to regions close to the jet nozzle exit. The results are discussed in terms of the instantaneous and time-and spatialaveraged flow properties.…”

Section: Computational Detailsmentioning

confidence: 99%

“…2, it is evident that the dispersion of the liquid is dominated by large-scale vortical structures formed at the jet primary stream due to the Kelvin-Helmholtz-type shear layer instability. The presence of streamwise vorticity, which is absent in idealized axisymmetric and planar configurations, [27][28][29] is generated by 3D vortex stretching and interaction. The flow vorticity dominates the dispersion of the liquid as indicated by the similar structures of the enstrophy and liquid volume fraction.…”

Section: Computational Detailsmentioning

confidence: 99%

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Direct numerical simulation of the near-field dynamics of annular gas-liquid two-phase jets

2009

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Direct numerical simulation has been used to examine the near-field dynamics of annular gas-liquid two-phase jets. Based on an Eulerian approach with mixed fluid treatment, combined with an adapted volume of fluid method and a continuum surface force model, a mathematical formulation for the flow system is presented. The swirl introduced at the jet nozzle exit is based on analytical inflow conditions. Highly accurate numerical methods have been utilized for the solution of the compressible, unsteady, Navier-Stokes equations. Two computational cases of gas-liquid two-phase jets including swirling and nonswirling cases have been performed to investigate the effects of swirl on the flow field. In both cases the flow is more vortical at the downstream locations. The swirling motion enhances both the flow instability resulting in a larger liquid spatial dispersion and the mixing resulting in a more homogeneous flow field with more evenly distributed vorticity at the downstream locations. In the annular nonswirling case, a geometrical recirculation zone adjacent to the jet nozzle exit was observed. It was identified that the swirling motion is responsible for the development of a central recirculation zone, and the geometrical recirculation zone can be overwhelmed by the central recirculation zone leading to the presence of the central recirculation region only in the swirling gas-liquid case. Results from a swirling gas jet simulation were also included to examine the effect of the liquid sheet on the flow physics. The swirling gas jet developed a central recirculation region, but it did not develop a precessing vortex core as the swirling gas-liquid two-phase jet. The results indicate that a precessing vortex core can exist at relatively low swirl numbers in the gas-liquid two-phase flow. It was established that the liquid greatly affects the precession and the swirl number alone is an insufficient criterion for the development of a precessing vortex core.

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