Numerical study of turbulent boundary layers with heat transfer and tangential transpiration

Çuhadaroğlu, Burhan

doi:10.1108/09615530410544300

Cited by 8 publications

(5 citation statements)

References 17 publications

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“…Along the free boundaries, where the flow field is considered fully developed, the gradients normal to the boundary and normal velocity vanish as: (Equation 10) At the outlet computation domain, which placed at x/H = 25.5 downstream of the cylinder, a zero streamwise gradient is specified as: (Equation 11) In the near‐porous wall region, which has two sub‐layers, two different formulas have been used in computational algorithm. Regarding y‐direction as normal direction, the viscous sub‐layer was simulated as (Equation 12) and in the log‐law layer (Equation 13) has been regarded with the constants of u p + = y p + = 11.5 and κ = 0.4 (Çuhadaroğlu, 2004). Finally, the WFs used in this study can be summarized as follows: (Equation 14) Near the wall, the log‐law region is in local equilibrium so that the rate of turbulence kinetic energy production is approximately equal to its dissipation rate.…”

Section: Mathematical Formulationmentioning

confidence: 99%

“…Meinert et al (2001) showed that transpiration of a foreign gas through a porous wall into a turbulent boundary layer has a strong influence on heat transfer between the wall and the main flow. Çuhadaroğlu (2004) numerically studied the effects of tangential transpiration on the characteristics of turbulent boundary layer and found that local friction coefficient and thermal boundary layer thickness are substantially influenced by the velocity and the angle of transpiration.…”

Section: Introductionmentioning

confidence: 99%

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A numerical study on turbulent flow around a square cylinder with uniform injection or suction

Çuhadaroğlu

2009

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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PurposeThis paper aims to predict the effects of uniform injection or suction through a porous square cylinder on the flow field and on some aerodynamic parameters.Design/methodology/approachThe finite volume method has been used for solving the ensemble averaged Navier–Stokes equations for incompressible flow in conjunction with the k‐ ε turbulence model equations including the Kato and Launder modification.FindingsThe parameters taken into account are injection or suction velocity, position of injection and suction surface, drag and lift coefficients and Strouhal number. The numerical results show that increasing suction velocity decreases the drag coefficient for all the suction configurations considered in the present study, except that of suction through rear surface. The vortex‐shedding motion gets weak by the suction application through top and bottom surfaces.Research limitations/implicationsThe problem is restricted with a 2‐D simple geometry such as square cylinder due to the limited computer capability. Further extensions of the present study could include the more complex configurations and some other aspects such as heat transfer between porous cylinder and main flow.Practical implicationsThe injection or suction application through a porous bluff body can be used as an efficient drag and vortex control method in aerodynamics.Originality/valueThis paper describes an attempt to simulate numerically the flow around square cylinder with uniform injection and suction in a manner different from what is given in the literature.

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Section: Mathematical Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A numerical study on turbulent flow around a square cylinder with uniform injection or suction

Çuhadaroğlu

2009

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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“…The CFD calculation needs to select the fluid and heat transfer model. The model mainly has the turbulence model to select the RNG k-ε model (Merci et al , 2002; Cuhadaroglu, 2004; Raisee et al , 2004; Gorecki and Szumbarski, 2014). When calculating convection, the ideal air equation is selected to describe component concentration and to solve natural convection.…”

Section: Computational Fluid Dynamics Simulation Analysis and Verificationmentioning

confidence: 99%

Simulation study on the effect of underwear on thermal reaction of human body based on heat and mass transfer theory

Cheng

Chen

2019

HFF

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Purpose The purpose of this paper is to analyze the influence of underwear on the microenvironment of human clothing. Design/methodology/approach Based on the basic laws of energy and mass conservation, the paper combined the theory of heat and mass transfer to establish the simulation of the influence of underwear on human thermal reaction in microclimate and prediction model of human thermal reaction law. Findings The impact on the microenvironment affected by tighter underwear is less than the effect of loose underwear and computational flow dynamics (CFD) can accurately predict the thermal reaction parameters’ values of the human body. Originality/value It can be effectively used for the prediction of heat exchange between human body and environment in high-temperature environment and human thermophysiological parameters, and overcomes the individual differences of human experiments and the danger and repeatability of high-temperature environmental experiments.

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“…Fransson et al (2004) found that continuous injection and suction at moderate levels through the cylinder walls strongly influenced the surface pressure distribution, vortex shedding frequency and the wake flow behind a porous circular cylinder. Çuhadaroǧlu (2004) numerically analyzed hydrodynamic and thermal characteristics of the turbulent boundary layer and reported that the characteristics of the turbulent boundary layer are essentially affected by velocity and angle of transpiration. An experimental study on the effects of uniform transpiration through one perforated surface of a square cylinder on the pressure distribution and drag coefficient in a 2D turbulent flow was presented by Çuhadaroǧlu et al (2007).…”

Section: Introductionmentioning

confidence: 99%

Effects of uniform injection and suction through perforated pentagonal cylinders on the flow and heat transfer

Vakhshouri

Çuhadaroğlu

2021

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Purpose The purpose of this paper is to study the effects of uniform injection and suction through a perforated pentagonal cylinder on the flow field and heat transfer. Design/methodology/approach The finite-volume method has been used to solve the ensemble-averaged Navier-Stokes equations for incompressible flow at moderate Reynolds number (Re = 22,000) with the k-ɛ turbulence model equations. Findings A computational fluid dynamics analysis of turbulent flow past a non-regular pentagonal cylinder with three different aspect ratios aspect ratios has been carried out to investigate the effects of uniform injection/suction through the front and all surfaces of the cylinder. It is found that flow field parameters such as drag coefficient, pressure coefficient and Nusselt number are affected considerably in some cases depend on injection/suction rate (Γ) and perforated wall position. Research limitations/implications To optimize the efficiency of the injection and suction through a perforated surface, both wide-ranging and intensive further studies are required. Using various perforation ratios and injection/suction intensities are some possibilities. Practical implications Control of the vortex shedding and wake region behind bluff bodies is of vital interest in fluid dynamics. Therefore, applying uniform injection and suction from a perforated bluff body into the main flow can be used as a drag reduction mechanism, thermal protection and heat transfer enhancement. Originality/value This study provides unique insights into the active flow control method around pentagonal cylinders that can be useful for researchers in the field of fluid dynamics and aeronautics.

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Numerical study of turbulent boundary layers with heat transfer and tangential transpiration

Cited by 8 publications

References 17 publications

A numerical study on turbulent flow around a square cylinder with uniform injection or suction

A numerical study on turbulent flow around a square cylinder with uniform injection or suction

Simulation study on the effect of underwear on thermal reaction of human body based on heat and mass transfer theory

Effects of uniform injection and suction through perforated pentagonal cylinders on the flow and heat transfer

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