Numerical Analysis on Effect of Jet Injection on Vortex Shedding for Flow Over a Circular Cylinder

Karthikeyan, S.; Senthilkumar, S.; Kannan, B. T.; Chandrasekhar, U.

doi:10.1007/s13369-018-3588-1

Cited by 14 publications

(6 citation statements)

References 33 publications

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“…The velocity and pressure fields were coupled using the SIMPLEC algorithm, and the second-order upwind scheme was selected for solving the momentum and energy equations [34]. The first-order implicit time-marching scheme with a fixed time step of 1.2 × 10 −6 s was employed for the transient solution [30]. All the computations were considered converged with a convergence threshold residual of 10 × 10 −6 for both the continuity and velocities [25].…”

Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

“…Except that the bottom wall (A) behind the cylinder (L 2 = 9.925 mm), colored in red, was a constant heat wall, of which the temperature was kept at T max = 353 K, the others were adiabatic walls. Meanwhile, the temperature of incoming flow was T inlet = 293 K, and the injection ratio (I) is defined as the ratio between the jet velocity and the inlet velocity, according to Karthikeyan et al's study [30]. The jet angle (θ) is defined as the angle between the jet slit and the positive direction of the X-axis in the study.…”

Section: Physical Model and Problem Statementmentioning

confidence: 99%

“…Firstly, the effects of the jet on wake vortices from the cylinder have received more attention. Shi et al [29] found that the jet had an obvious disturbance effect on the flow field, and Karthikeyan et al [30] deeply studied the effect of a jet on vortex shedding from a cylinder. The results of Jung [31,32] showed that due to the length-diameter ratio of the cylinder and the microchannel wall bound, the disturbance of the wake vortices to the flow field was suppressed at a low Reynolds number (less than the critical Reynolds number Re cr = 400).…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of Heat Transfer in a Microchannel via Passive and Active Control of a Jet Issued from the Circular Cylinder

Xin¹,

Kong²,

Chen³

2022

Energies

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The heat transfer enhancement of a jet issued from the circular cylinder placed in a three-dimensional microchannel at low Reynolds numbers were studied systematically by using the numerical simulation. The effects of the jet on thermal efficiency were evaluated by varying injection ratios (I) and jet angles (θ). The physical mechanism of heat transfer was revealed through the analyses of vorticity dynamic and temperature field. The results showed that the thermal efficiency was proportional to the injection ratio at Re = 100 and 200. However, at Re = 300, the thermal efficiency did not increase monotonically with the injection ratio, and the local maximum value of heat transfer efficiency, slightly less than the highest thermal efficiency, appeared at I = 1.5. This was a result of the jet inducing the vortex generated on the cylinder to become unstable. Furthermore, the change of jet angle had a better effect on heat transfer performance compared to the increase in the injection ratio. The separation point of the flow over cylinder and the vortices in the near field were adjusted by the change in jet angle. At the appropriate range of the jet angle, the wake vortices in the near field transitioned from quasi-steady to unsteady in the far field. The instability of wake vortices can disturb the thermal boundary layer near the wall so as to improve the heat transfer performance.

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Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

Section: Physical Model and Problem Statementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enhancement of Heat Transfer in a Microchannel via Passive and Active Control of a Jet Issued from the Circular Cylinder

Xin¹,

Kong²,

Chen³

2022

Energies

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“…Bruno et al 36 performed a numerical investigation of flow over two and three-dimensional rectangular bluff bodies at high Re L . Karthikeyan et al 40 numerically simulated and analyzed the combined effects of vortex shedding, undulation, and jet-wake dominant phenomena over a circular cylinder. The authors identified properties such as c l , c d and power spectral density (PSD).…”

Section: Introductionmentioning

confidence: 99%

Unsteady dynamics in a subsonic duct flow with a bluff body

George,

Karthick,

Srikrishnan

et al. 2022

Preprint

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A series of reduced-order numerical simulations on a specific bluff body type (v-gutters) in a subsonic duct flow is done to assess the unsteady wake dynamics. Two of the v-gutter's geometrical parameters are varied: the v-gutter's base angle (θ ) and the size of a slit (ξ ) at the leading-edge of the v-gutter. Turbulent flow kinematics and pressure field are analyzed to evaluate the unsteadiness at a freestream Mach number of M ∞ = 0.25 and a freestream Reynolds number based on bluff body's transverse length (L) of Re L = 0.1 × 10 6 . Five v-gutter angles are considered (θ , • = π/6, π/4, π/3, 5π/12, π/2) and three slit sizes (ξ , mm =0,0.25,0.5) are considered only for a particular θ = [π/6]. In general, high fluctuations in velocity and pressure are seen for the bluffest body in consideration (θ = π/2) with higher drag (c d ) and total pressure loss (∆p 0 ). However, bluffer bodies produce periodic shedding structures that promote flow mixing. On the other hand, the presence of a slit on a streamlined body (θ = π/6) tends to efficiently stabilize the wake and thus, producing almost a periodic shedding structure with lower c d and ∆p 0 . For θ = [π/6], broadened spectra in vortex shedding is seen with a peak at [ f L/u ∞ ] ∼ 0.08. For θ ≥ [π/4], a dominant discrete shedding frequency is seen with a gradual spectral decay. Similarly, the effects of ξ on the θ = [π/6] case produce a discrete shedding frequency instead of a broadened one, as told before. The shedding frequency increases to a maximum of [ f L/u ∞ ] ∼ 0.26 for the maximum slit size of ξ = 0.5. From the analysis of the x − t diagram and the modal analysis of vorticity and velocity magnitude in the wake, the peaks are indeed found to agree with the spectral analysis. More insights on the shedding vortices, momentum deficit in the wake, varying energy contents in the flow field, and the dominant spatiotemporal structures are also provided.

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“…The study of vortex shedding (VS) phenomena for the flow over a bluff body (circular and square cylinder) have been a topic of interest due to its application in cooling of electronic devices, heat exchangers, mixing phenomena, design of bridge and cooling towers [1][2][3][4][5][6]. The onset of VS occurs at some critical Reynolds number, which depends on the geometry of bluff bodies.…”

Section: Introductionmentioning

confidence: 99%

Effect of Thermal Buoyancy on Vortex-Shedding and Aerodynamic Characteristics for Fluid Flow Past an Inclined Square Cylinder

Arif¹,

Hasan²

2020

IJHT

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The present work aims to numerically investigate the upward flow of air past an inclined square cylinder with an incidence angle equal to 45 o in the mixed convection regime at a fixed Reynolds number Re = 100. The governing equations are modelled by considering Boussinesq approximation. The critical Richardson number (Ric) for the suppression of vortex shedding (VS) is determined. By observing the instantaneous streamline patterns and the coefficient of lift plot with time near the critical value, it is found that VS suppression occurs at Ric = 0.78. Also, the aerodynamic characteristics such as lift and drag coefficient, the heat transfer characteristic, and the Strouhal number are studied by varying Ri in the range of [0.2, 1]. The role of thermal buoyancy on the aerodynamic parameters such as drag and lift coefficients, Nusselt number and Strouhal number are also studied in the mixed convection regime. It is found that mean drag coefficient and Nusselt number increases with the increase in Ri, and no lift is developed for any Ri, while the Strouhal number increases with increase in Ri and vanishes at a critical Richardson number. Further, the effect of thermal buoyancy on streamlines, isotherms and iso-vorticity contours are also presented.

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Numerical Analysis on Effect of Jet Injection on Vortex Shedding for Flow Over a Circular Cylinder

Cited by 14 publications

References 33 publications

Enhancement of Heat Transfer in a Microchannel via Passive and Active Control of a Jet Issued from the Circular Cylinder

Enhancement of Heat Transfer in a Microchannel via Passive and Active Control of a Jet Issued from the Circular Cylinder

Unsteady dynamics in a subsonic duct flow with a bluff body

Effect of Thermal Buoyancy on Vortex-Shedding and Aerodynamic Characteristics for Fluid Flow Past an Inclined Square Cylinder

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