Channel flow with large longitudinal ribs

Castro, Ian P.; Kim, Jae Wook; Stroh, Alexander; Lim, Hee-Chang

doi:10.1017/jfm.2021.110

Cited by 19 publications

(48 citation statements)

References 36 publications

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“…2b,c. The profiles confirm that the HMP and downwash region is located in between the ridges while the LMP and upwash is observed above the ridges which is consistent with observations in the literature (Vanderwel and Ganapathisubramani, 2015;Medjnoun et al, 2018;Castro et al, 2021). The ongoing progress of this work includes: stereo-PIV measurements in the cross-plane, frequency analysis, and quantification of inner-outer interactions in this flow scenario.…”

Section: Resultssupporting

confidence: 89%

“…In a particular scenario, when the surface heterogeneity is predominantly in the spanwise direction of the flow, this roughness heterogeneity can generate secondary flow in cross flow plane which is very different from smooth-wall or homogeneous rough-wall boundary layers. A number of experimental (Barros and Christensen, 2014;Vanderwel and Ganapathisubramani, 2015;Zampiron et al, 2020) and numerical (Anderson et al, 2015;Hwang and Lee, 2018;Castro et al, 2021) studies have shown features associated with the secondary flow including: streamwise oriented alternating lowand high-momentum pathways (LMP, HMP); downwash and upwash flow at HMP and LMP, respectively; counter-rotating streamwise vortices formed across an LMP and HMP. The secondary flow mechanism is explained based on Prandtl's secondary flow of the second kind according to Anderson et al (2015).…”

Section: Introductionmentioning

confidence: 99%

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PIV measurements in a turbulent boundary layer overlying a spanwise heterogeneous roughness

Yao¹,

Christensen²

2021

ISPIV21

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In nature and engineering applications, wall-bounded flow often encounter a heterogeneous surface condition, such as the atmosphere boundary layer at the urban boundary and flow over riveted aircraft surfaces. In a particular scenario, when the surface heterogeneity is predominantly in the spanwise direction of the flow, this roughness heterogeneity can generate secondary flow in cross flow plane which is very different from smooth-wall or homogeneous rough-wall boundary layers.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

PIV measurements in a turbulent boundary layer overlying a spanwise heterogeneous roughness

Yao¹,

Christensen²

2021

ISPIV21

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“…( 2)) at every time instant of the simulation. This IBM implementation was validated for rough surfaces by Forooghi et al (2018) and has successfully been used in previous works on secondary motions generated through longitudinal ribs (Stroh et al 2019;Castro et al 2021).…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, novel modelling concepts for spanwise irregular rough surfaces have to be developed as outlined by Chung et al (2021). It was recently demonstrated by Castro et al (2021) that the spanwise averaged flow field above streamwise aligned ribs can be described with a modified log-law taking into account the increase of wetted surface area. It might thus be possible to predict the global effect of ridge-type roughness onto the spanwise averaged flow field through a prescription of a velocity profile that is tuned to include the Reynolds number dependency of the generated friction drag.…”

Section: Reynolds Number Dependency Of the Friction Coefficientmentioning

confidence: 99%

Ridge-type roughness: from turbulent channel flow to internal combustion engine

et al. 2021

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While existing engineering tools enable us to predict how homogeneous surface roughness alters drag and heat transfer of near-wall turbulent flows to a certain extent, these tools cannot be reliably applied for heterogeneous rough surfaces. Nevertheless, heterogeneous roughness is a key feature of many applications. In the present work we focus on spanwise heterogeneous roughness, which is known to introduce large-scale secondary motions that can strongly alter the near-wall turbulent flow. While these secondary motions are mostly investigated in canonical turbulent shear flows, we show that ridge-type roughness—one of the two widely investigated types of spanwise heterogeneous roughness—also induces secondary motions in the turbulent flow inside a combustion engine. This indicates that large scale secondary motions can also be found in technical flows, which neither represent classical turbulent equilibrium boundary layers nor are in a statistically steady state. In addition, as the first step towards improved drag predictions for heterogeneous rough surfaces, the Reynolds number dependency of the friction factor for ridge-type roughness is presented. Graphic abstract

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“…As noted in [81], the term "roughness" is used sometimes by different research groups in different meanings. Two different types of the wall structuring can be meant under this term, namely, small-scale (about 10% of the boundary layer thickness) smooth structures, homogeneous in the flow direction and produced exceptionally by transverse variations in the wall height (for example, longitudinal ridges of different shapes on a smooth wall) and irregular rough surfaces with multidirectional variations in the surface height (for example, roughness streaks).…”

Section: Secondary Flows Near Rough Surfacesmentioning

confidence: 99%

Prandtl’s Secondary Flows of the Second Kind. Problems of Description, Prediction, and Simulation

2021

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Abstract— The occurrence of turbulent pulsations in straight pipes of noncircular cross-section leads to the situation, when the average velocity field includes not only the longitudinal component but also transverse components that form a secondary flow. This hydrodynamic phenomenon discovered at the twenties of the last century (J. Nikuradse, L. Prandtl) has been the object of active research to the present day. The intensity of the turbulent secondary flows is not high; usually, it is not greater than 2–3% of the characteristic flow velocity. Nevertheless, their contribution to the processes of transverse transfer of momentum and heat is comparable to that of turbulent pulsations. In this paper, a review of experimental, theoretical, and numerical studies of secondary flows in straight pipes and channels is given. Emphasis is placed on the issues of revealing the physical mechanisms of secondary flow formation and developing the models of the apriori assessment of their forms. The specific features of the secondary flow development in open channels and channels with inhomogeneously rough walls are touched upon. The approaches of semiempirical simulation of turbulent flows in the presence of secondary flows are discussed.

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Channel flow with large longitudinal ribs

Abstract: Abstract

Cited by 19 publications

References 36 publications

PIV measurements in a turbulent boundary layer overlying a spanwise heterogeneous roughness

PIV measurements in a turbulent boundary layer overlying a spanwise heterogeneous roughness

Ridge-type roughness: from turbulent channel flow to internal combustion engine

Prandtl’s Secondary Flows of the Second Kind. Problems of Description, Prediction, and Simulation

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