<p>This study investigates the interaction of a vortex ring with perforated plates of different thicknesses, with a focus on the near-wall events in the downstream region. Experimental techniques like planar laser-induced fluorescence imaging and particle image velocimetry were employed to understand the flow physics. Two different configurations of interaction, based on the alignment of the vortex ring relative to the center hole of the perforation, were investigated. Three different plate thicknesses (3, 5, and 8 mm) were considered to elucidate its role on the downstream physics. The study was conducted for a vortex ring with a circulation-based Reynolds number <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$(Re_\Gamma )$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>R</mi> <msub> <mi>e</mi> <mi mathvariant="normal">Γ</mi> </msub> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> of 9000. The arrival of a vortex ring near the perforated plate resulted in the formation of mushroom-like structures in the downstream near the wall, influencing the jets formed below. The kinetic energy of the fluid due to these structures was found to be as high as <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\sim$</EquationSource> <EquationSource Format="MATHML"><math> <mo>∼</mo> </math></EquationSource> </InlineEquation> 20–30% of the total kinetic energy achieved in the downstream region. The downstream <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\Gamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Γ</mi> </math></EquationSource> </InlineEquation> peak was found to be nearly independent of the plate thickness, whereas the peak kinetic energy and enstrophy decreased with higher thickness. The shear layer interaction dynamics between downstream jets are explained through instantaneous and time-averaged velocity and vorticity fields. The cumulative slug model is used to estimate the <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$\Gamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Γ</mi> </math></EquationSource> </InlineEquation> growth in the downstream using the centerline peak velocity of each jet. Finally, a scaling is proposed that yields an inverse relation between the time-averaged axial velocity peak in the downstream and the aspect ratio (<i>AR</i> = ratio of plate thickness to hole diameter).</p>

Characterizing near-wall downstream events during a vortex ring interacting with a perforated plate

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发表日期：

2026年1月11日

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Siddhant Jain,
Saini Jatin Rao,
Saurabh Sharma,
Saptarshi Basu

摘要

This study investigates the interaction of a vortex ring with perforated plates of different thicknesses, with a focus on the near-wall events in the downstream region. Experimental techniques like planar laser-induced fluorescence imaging and particle image velocimetry were employed to understand the flow physics. Two different configurations of interaction, based on the alignment of the vortex ring relative to the center hole of the perforation, were investigated. Three different plate thicknesses (3, 5, and 8 mm) were considered to elucidate its role on the downstream physics. The study was conducted for a vortex ring with a circulation-based Reynolds number $(Re_\Gamma )$ $(R e_{Γ})$ of 9000. The arrival of a vortex ring near the perforated plate resulted in the formation of mushroom-like structures in the downstream near the wall, influencing the jets formed below. The kinetic energy of the fluid due to these structures was found to be as high as $\sim$ $\sim$ 20–30% of the total kinetic energy achieved in the downstream region. The downstream $\Gamma$ $Γ$ peak was found to be nearly independent of the plate thickness, whereas the peak kinetic energy and enstrophy decreased with higher thickness. The shear layer interaction dynamics between downstream jets are explained through instantaneous and time-averaged velocity and vorticity fields. The cumulative slug model is used to estimate the $\Gamma$ $Γ$ growth in the downstream using the centerline peak velocity of each jet. Finally, a scaling is proposed that yields an inverse relation between the time-averaged axial velocity peak in the downstream and the aspect ratio (AR = ratio of plate thickness to hole diameter).