Verification of drag-reduction capabilities of stiff compliant coatings in air flow at moderate speeds

Бойко, А. В.; Kulik, V. M.; Hu, Chun; Lee, Inwon

doi:10.3744/jnaoe.2011.3.4.242

Cited by 3 publications

(2 citation statements)

References 21 publications

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“…2005; Boiko et al. 2011). Ongoing and future research on the coating-equipped test plates require a viscoelastic material that maintains its mechanical properties over a sufficient period of time.…”

Section: Experimental Approachmentioning

confidence: 99%

“…Polydimethylsiloxane (PDMS) has conventionally been applied as compliant viscoelastic material in fluid-surface interaction studies (Hess et al 1993;Choi et al 1997;Colley et al 1999;Zhang et al 2015Zhang et al , 2017. Nevertheless, due to a continuous progress of covalent cross-link reactions between polymer chains, PDMS samples experience an ageing process that modifies the mechanical properties of the material (Bandyopadhyay et al 2005;Boiko et al 2011). Ongoing and future research on the coating-equipped test plates require a viscoelastic material that maintains its mechanical properties over a sufficient period of time.…”

Section: Compliant Materialsmentioning

confidence: 99%

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Response regimes in the fluid–structure interaction of wall turbulence over a compliant coating

et al. 2022

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The interaction between a turbulent boundary layer flow and compliant surfaces is investigated experimentally. Three viscoelastic coatings with different material stiffnesses are used to identify the general surface response to the turbulent flow conditions. For the softest coating, the global force measurements show two obvious regimes of interaction with an indicated transition at $U_b/C_t\sim 3.5$ , where $U_b$ is the bulk flow velocity and $C_t$ is the coating shear velocity. The one-way coupled regime shows friction values comparable to those of the rigid wall, while the two-way coupled regime indicate a significant increase in fluid friction. Within the one-way coupled regime for $U_b/C_t>1.2$ , the flow measurements show a low level of two-way coupling represented by the change of the velocity profile as well as the increase in the Reynolds stresses in the near-wall region. This is supported by the surface deformation measurements. Initially, the turbulent flow structures induce only an imprint on the coating surface, while a change in surface response occurs when the surface wave propagation velocity $c_w$ equals the shear wave velocity of the coating $C_t$ (i.e. $c_w/C_t\sim 1$ ). Above $U_b/C_t>1.2$ , a growth in wavelength is observed with increasing flow velocity, most probably due to the surface wave formation generated downstream the pressure features of the flow. The surface response is stable and correlates with the high-intensity turbulent pressure fluctuations in the turbulent boundary layer, with a wave propagation velocity $c_w\sim 0.7\unicode{x2013}0.8$ $U_b$ . Within the two-way coupled regime, additional fluid motions and a downward shift in the logarithmic region of the velocity profile are observed due to substantial surface deformation and confirm the frictional drag increase. Another type of surface response is initiated by phase-lag instability in combination with surface undulations that start to protrude the viscous sublayer, where the propagation velocity of surface wave trains is $c_w\sim 0.17\unicode{x2013}0.18$ $U_b$ .

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Section: Experimental Approachmentioning

confidence: 99%

Section: Compliant Materialsmentioning

confidence: 99%

Response regimes in the fluid–structure interaction of wall turbulence over a compliant coating

et al. 2022

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Passive Drag Reduction Technologies

Kouser,

Zulfiqar,

Misbah

et al. 2023

ChemBioEng Reviews

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The developments and involved factors of mature passive drag reduction technologies, i.e., compliant coating, superhydrophobic surfaces, and epoxy coating, are reviewed. Alterations in critical Reynolds number are observed in the presence of passive drag reduction technologies. With the advancement in technology, numerical approaches are introduced to lower the cost and achieve better understanding of physical phenomena such as lowering energy, flow control, designing the surfaces of materials, and so on. Experimental results as well as numerical results are stated. The effects of factors like wetting, contact angle, contact angle hysteresis, roughness, pot life, and coating aging responsible for drag reduction are also briefly presented with numerical and experimental perspective analyses.

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Study on the Drag Reduction of 2-D Dimpled-Plates

Paik¹,

Pyun²,

Kim³

et al. 2012

Journal of the Society of Naval Architects of Korea

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The main objective of the present study is to investigate the roles of the micro-dimpled surface on the drag reduction. To investigate the effectiveness of the micro-dimpled surface, the flat plates are prepared. The micro-size dimples are directly carved on the metal surface by ultrasonic nano-crystal surface modification (UNSM) method. Momentum of the main flow is increased by the dimple patterns within the turbulent boundary layer (TBL), however, there is no significant change in the turbulence intensity in the TBL.

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Verification of drag-reduction capabilities of stiff compliant coatings in air flow at moderate speeds

Abstract: Skin frictional drag reduction efficiency of "stiff" compliant coating was investigated in a wind

Cited by 3 publications

References 21 publications

Response regimes in the fluid–structure interaction of wall turbulence over a compliant coating

Response regimes in the fluid–structure interaction of wall turbulence over a compliant coating

Passive Drag Reduction Technologies

Study on the Drag Reduction of 2-D Dimpled-Plates

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