On skin friction in wall-bounded turbulence

Xia, Zhenhua; Zhang, Peng; Yang, Xiang

doi:10.1007/s10409-020-01024-4

Cited by 12 publications

(10 citation statements)

References 22 publications

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“…Theoretically speaking, equations ( 10) and ( 11) can be used to estimate q w . However, there might be considerable errors coming from the imperfect balance of the equations due to the insufficient sample sizes (see similar results for the skin-friction by Xia et al 17 ).…”

Section: Exact Mathematical Formulas For the Wall Heat Flux Qwmentioning

confidence: 66%

“…It should be noted that the FIK decomposition is an exact mathematical formula, and thus it can be used to estimate the skin friction coefficients. Following the idea of the FIK decomposition, Mehdi and his collaborators 15,16 proposed an integral formula to estimate the skin friction coefficient in wall-bounded turbulence by using the experimental data, and Xia et al 17 further derived the skin friction coefficient formulas for incompressible turbulent channel flows and turbulent boundary layer flows with zero pressure gradient in terms of the mean velocity and the Reynolds shear stress in an arbitrary wall-normal region.…”

Section: Introductionmentioning

confidence: 99%

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Contribution of viscous stress work to wall heat flux in compressible turbulent channel flows

Zhang

Xia

2020

Phys. Rev. E

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In this paper, several exact expressions for the mean heat flux at the wall (q w ) for the compressible turbulent channel flows are derived by using the internal energy equation or the total energy equation. Two different routes, including the FIK method and the RD method, can be applied. The direct numerical simulations data of compressible channel flows at different Reynolds and Mach numbers verify the correctness of the derived formulas. Discussions related to the different energy equations, and different routes are carried out, and we may arrive at the conclusion that most of the formulas derived in the present work are just mathematically ones which generally are lack of clear physical interpretation. They can be used to estimate q w , but might not be suitable for explore the underlying physics.

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Section: Exact Mathematical Formulas For the Wall Heat Flux Qwmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Contribution of viscous stress work to wall heat flux in compressible turbulent channel flows

Zhang

Xia

2020

Phys. Rev. E

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“…2002; Xia et al. 2021; Wenzel et al. 2021 a ), mean kinetic energy (Renard & Deck 2016), mean energy (Arntz, Atinault & Merlen 2015), mean total enthalpy (Wenzel et al.…”

Section: Decompositions Of the Skin-friction And Heat-transfer Coeffi...mentioning

confidence: 99%

“…Similar to the idea of Mehdi et al. (2014), Xia, Zhang & Yang (2021) expressed the skin friction by the mean velocity and the Reynolds shear stress in an arbitrary wall-normal region.…”

Section: Introductionmentioning

confidence: 96%

Skin-friction and heat-transfer decompositions in hypersonic transitional and turbulent boundary layers

Wang

Chen

2022

J. Fluid Mech.

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The decompositions of the skin-friction and heat-transfer coefficients based on the twofold repeated integration in hypersonic transitional and turbulent boundary layers are analysed to give some major reasons of the overshoot phenomena of the wall skin friction and heat transfer. It is shown that the overshoot of the skin-friction coefficient is mainly caused by the drastic change of the mean velocity profiles, especially the strong negative streamwise gradient of the mean streamwise velocity far from the wall; and the overshoot of the heat-transfer coefficient is primarily due to the viscous dissipation, especially the strong positive vertical gradient of the mean streamwise velocity near the wall. These observations are different from the previous observations that the Reynolds shear stress and Reynolds heat flux are the reasons, respectively. Further investigations show that the above observations are independent of the set-up of the wall blowing and suction parameters, which indicates the universality of the major reasons of the overshoot phenomena in our numerical simulations. In the hypersonic turbulent boundary layers, it is observed that the strongly cooled wall temperature and the high Mach number can slightly enhance the contribution of the Reynolds shear stress, and weaken the contribution of the mean convection, mainly due to the strong compressibility effect. Moreover, the magnitudes of the relative contributions of the mean convection, pressure dilatation, viscous dissipation and the Reynolds heat flux increase as the wall temperature increases.

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“…The resulting equation is equivalent to that of a single integration of the first moment of momentum, . Xia, Zhang & Yang (2021) considered a similar double-integration procedure for predicting the wall shear stress from outer flow measurements. Double integral (or first moment) relations have also recently been introduced for high-speed boundary layers (Xu, Wang & Chen 2021; Wenzel, Gibis & Kloker 2022).…”

Section: Background and Theorymentioning

confidence: 99%

On the enhancement of boundary layer skin friction by turbulence: an angular momentum approach

Elnahhas

Johnson

2022

J. Fluid Mech.

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Turbulence enhances the wall shear stress in boundary layers, significantly increasing the drag on streamlined bodies. Other flow features such as free stream pressure gradients and streamwise boundary layer growth also strongly influence the local skin friction. In this paper, an angular momentum integral (AMI) equation is introduced to quantify these effects by representing them as torques that alter the shape of the mean velocity profile. This approach uniquely isolates the skin friction of a Blasius boundary layer in a single term that depends only on the Reynolds number most relevant to the flow's engineering context, so that other torques are interpreted as augmentations relative to the laminar case having the same Reynolds number. The AMI equation for external flows shares this key property with the so-called FIK relation for internal flows (Fukagata et al., Phys. Fluids, vol. 14, 2002, pp. L73–L76). Without a geometrically imposed boundary layer thickness, the length scale in the Reynolds number for the AMI equation may be chosen freely. After a brief demonstration using Falkner–Skan boundary layers, the AMI equation is applied as a diagnostic tool on four transitional and turbulent boundary layer direct numerical simulation datasets. Regions of negative wall-normal velocity are shown to play a key role in limiting the peak skin friction during the late stages of transition, and the relative strengths of terms in the AMI equation become independent of the transition mechanism a very short distance into the fully turbulent regime. The AMI equation establishes an intuitive, extensible framework for interpreting the impact of turbulence and flow control strategies on boundary layer skin friction.

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On skin friction in wall-bounded turbulence

Cited by 12 publications

References 22 publications

Contribution of viscous stress work to wall heat flux in compressible turbulent channel flows

Contribution of viscous stress work to wall heat flux in compressible turbulent channel flows

Skin-friction and heat-transfer decompositions in hypersonic transitional and turbulent boundary layers

On the enhancement of boundary layer skin friction by turbulence: an angular momentum approach

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