The effect of the geometric features of the turbulent/non-turbulent interface on the entrainment of a passive scalar into a jet

Kohan, Khashayar F.; Gaskin, Susan

doi:10.1063/5.0019860

Cited by 19 publications

(17 citation statements)

References 61 publications

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“…The p.d.f. of for the jet in the quiescent ambient follows a Gaussian distribution, similar to previous studies (Mistry, Philip & Dawson 2019; Kohan & Gaskin 2020), while the distribution of for the jet in the turbulent ambient increasingly deviates from a Gaussian one due to a large skewness. The wide spans of the TNTI and TTI outline radial positions indicate the large-scale spatial fluctuations of , which are increasing with .…”

Section: Resultssupporting

confidence: 87%

“…. As noted in Kohan & Gaskin (2020), intense corrugation of the interface is characterised by , since these interface points radially fold back on themselves (see figure 7 of Kohan & Gaskin 2020). Figure 7( c ) shows the effect of ambient turbulence on the interface angle.…”

Section: Resultsmentioning

confidence: 73%

“…2015). Additional support is provided by Kohan & Gaskin (2020), who by coarse graining their PLIF resolution, show that a resolution of approximately 6 properly captures the conditionally averaged mean and r.m.s. scalar profiles.…”

Section: Methodsmentioning

confidence: 87%

“…The jet and the ambient regions are represented by and , respectively. Following Kohan & Gaskin (2020), we only consider points along with one flow status change (turbulent or ambient), i.e. we ignore points inside the islands and holes and after an intersection with them.…”

Section: Resultsmentioning

confidence: 99%

“…Using this definition, concave (bulges) and convex (valley) surface elements are identified as κ I < 0 and κ I > 0, respectively, when looking from the jet region. In Kohan & Gaskin (2020), it was suggested that the TNTI outline of the orthogonal cross-sections of the jet is dominated by flat concave surface elements (smooth bulges; see figure 1a), while its skewness is towards highly curved concave areas. Figure 7(b) reveals that the most probable curvature for all the background cases is at κ I d ≈ −3.…”

Section: The Tti Geometrymentioning

confidence: 99%

See 4 more Smart Citations

On the scalar turbulent/turbulent interface of axisymmetric jets

Kohan

Gaskin

2022

J. Fluid Mech.

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The effect of a zero-mean-flow turbulent ambient on the geometry of the turbulent/turbulent interface (TTI) of an axisymmetric jet is investigated and compared with the traditional turbulent/non-turbulent interface (TNTI). The ambient turbulence is generated using a random jet array. Orthogonal cross-sections of the jet subjected to different levels of ambient turbulence intensities and length scales are captured using planar laser-induced fluorescence. The enhanced radial transport of concentration from the jet core towards the interface and the increased scalar fluctuations within the jet caused by the ambient turbulence result in steeper mean and root-mean-square scalar conditional jumps across the TTI layer compared with those of the TNTI, respectively. When compared with the quiescent ambient, the mean effect of background turbulence is to stretch and corrugate the interface surface area as evident from the wider probability density of the interface radial position, the lowered occurrence of zero-curvature surface elements, the greater misalignment between the radial and normal unit vectors of the interface, the increased tortuosity and the increased magnitude of the fractal exponent.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 73%

Section: Methodsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: The Tti Geometrymentioning

confidence: 99%

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On the scalar turbulent/turbulent interface of axisymmetric jets

Kohan

Gaskin

2022

J. Fluid Mech.

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被动标量湍流的约束亚格子模型

et al. 2023

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Flow Field Characteristics at the Spanwise Edge of a Vegetative Canopy Model

Winiarska,

Liberzon,

van Hout

2024

Boundary-Layer Meteorol

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This study investigates the complex flow field across a spanwise vegetative model canopy edge focusing on turbulent transport processes. Utilizing stereoscopic particle image velocimetry, the three velocity components were measured in wall-parallel planes at various elevations within canopy across the spanwise canopy edge. Conventional ensemble averaged results were contrasted with those obtained by conditionally averaged flow properties across instantaneous internal interfaces in the flow to understand their contribution to the ensemble average. The conditional average captured the strong gradients in mean velocities, Reynolds stresses, vorticity, swirling strength, and turbulent kinetic energy production across the dynamically changing instantaneous interface. In contrast, the conventional ensemble average smeared out the strong gradients. Small magnitudes of advective terms in the turbulent kinetic energy transport equation suggested weak secondary transverse flows in the present model canopy. The turbulent flow structure across the spanwise canopy edge was further investigated using Quadrant-Hole analysis for both averaging approaches. Conventional ensemble averaged results indicated a shift from sweep to ejection dominance when moving from canopy into the open patch, while the conditional average showed only sweep dominated transport. In contrast to a homogeneous canopy layout, below canopy height at the canopy edge, sweeps and ejections lose their dominance in vertical turbulent transport. The present results show that the dynamics of internal interfaces govern the ensemble averaged results and a possible implementation into existing models is proposed. The present results are expected to increase understanding of spanwise turbulent transport and aid in developing strategies to mitigate desertification.

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The effect of the geometric features of the turbulent/non-turbulent interface on the entrainment of a passive scalar into a jet

Abstract: The effect of the geometric features of the turbulent/non-turbulent interface on the entrainment of a passive scalar into a jet

Cited by 19 publications

References 61 publications

On the scalar turbulent/turbulent interface of axisymmetric jets

On the scalar turbulent/turbulent interface of axisymmetric jets

被动标量湍流的约束亚格子模型

Flow Field Characteristics at the Spanwise Edge of a Vegetative Canopy Model

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