<p>Drag reduction in internal flows constitutes a critical area of flow control research, with substantial practical applications for water, oil, and gas pipeline systems. In such systems, viscous forces significantly contribute to turbulence, thereby increasing energy consumption, a major concern in the context of the global energy crisis and rising ambient temperatures. This study presents a numerical investigation of a novel passive drag reduction technique applied to fully developed circular pipe flows, involving the incorporation of a micron-scale slit along the pipe’s lateral surface. Computational fluid dynamics simulations, employing the <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$k-\varepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>k</mi> <mo>-</mo> <mi>ε</mi> </mrow> </math></EquationSource> </InlineEquation> turbulence model, well-suited for flows devoid of separation, were conducted to evaluate the impact of this slit on flow characteristics under both laminar and turbulent regimes. Numerical results indicate that a slit characterized by a width-to-pipe diameter ratio of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$4\times {10}^{-4}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>4</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>-</mo> <mn>4</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> yields drag of approximately 3.9% in laminar flow (Reynolds number of <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$2099.9$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>2099.9</mn> </mrow> </math></EquationSource> </InlineEquation>) and 10.26% in turbulent flow (Reynolds number of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$24880$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>24880</mn> </mrow> </math></EquationSource> </InlineEquation>). These findings substantiate the efficacy of the proposed passive method in mitigating internal drag and reducing energy consumption within pipeline transport systems.</p>

Reducing Drag in a Fully Developed Circular Pipe Flow with a Side Slit

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发表日期：

2025年9月12日

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S. Mahdi Sheikholeslam Noori,
Ali Shambayati

摘要

Drag reduction in internal flows constitutes a critical area of flow control research, with substantial practical applications for water, oil, and gas pipeline systems. In such systems, viscous forces significantly contribute to turbulence, thereby increasing energy consumption, a major concern in the context of the global energy crisis and rising ambient temperatures. This study presents a numerical investigation of a novel passive drag reduction technique applied to fully developed circular pipe flows, involving the incorporation of a micron-scale slit along the pipe’s lateral surface. Computational fluid dynamics simulations, employing the $k-\varepsilon$ $k - ε$ turbulence model, well-suited for flows devoid of separation, were conducted to evaluate the impact of this slit on flow characteristics under both laminar and turbulent regimes. Numerical results indicate that a slit characterized by a width-to-pipe diameter ratio of $4\times {10}^{-4}$ $4 \times 10^{- 4}$ yields drag of approximately 3.9% in laminar flow (Reynolds number of $2099.9$ $2099.9$ ) and 10.26% in turbulent flow (Reynolds number of $24880$ $24880$ ). These findings substantiate the efficacy of the proposed passive method in mitigating internal drag and reducing energy consumption within pipeline transport systems.