Effects of inlet and outlet boundary conditions on the flow field of synthetic      jets

Bazdidi–Tehrani, Farzad; Hatami, M.; Abouata, Ahmad

doi:10.1177/0954408915577338

Cited by 9 publications

(4 citation statements)

References 25 publications

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“…They have concluded that momentum flux downstream of the jet exit is largely independent of the orifice inner lip radius and considerable power can be saved by rounding the inner lip. Bazdidi-Tehrani et al (23) have considered the flow fields ensuing from confined and unconfined synthetic jets. In order to understand the effects of the simulation of the actuator on the results, they have simulated it via the dynamic mesh method in two ways, namely, moving-piston and moving-diaphragm boundaries.…”

Section: March 2016mentioning

confidence: 99%

Investigation of effects of compressibility, geometric and flow parameters on the simulation of a synthetic jet behaviour

et al. 2016

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The present paper focuses on a three-dimensional unsteady turbulent synthetic jet to assess the accuracy of a compressible simulation and some important parameters including the simulations of the actuator, cavity height and Reynolds number. The two-equation SST /k − ω turbulence model is used to predict the flow behaviour. Results show that the compressible simulation case is more accurate than the incompressible one and the dynamic mesh exhibits more reliable results than the mass flow inlet boundary in the compressible simulation. The compressible case displays a delay in the phase of instantaneous velocity for all three Reynolds numbers. Also, the maximum of mean velocity is less than the incompressible case. Moreover, an increase in the Reynolds number leads to an amplification of the peak of mean velocity magnitude. Finally, results demonstrate that a reduction in the cavity height regarding the compressible simulation case causes a reduction in the phase delay and rise in peak of instantaneous velocity magnitude.

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Section: March 2016mentioning

confidence: 99%

Investigation of effects of compressibility, geometric and flow parameters on the simulation of a synthetic jet behaviour

et al. 2016

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“…Since this study allows the fluid to flow out of the computational domain naturally, the pressure outlet is chosen as the boundary condition, which helps to reduce the fluid reflection and flow disturbances at the end of the computational domain, thus improving the accuracy of the simulation. The basis for this choice is consistent with Xia et al [47] and Bazdidi et al [48]. A velocity inlet is positioned two L upstream, and a pressure outlet is situated four L downstream of the suboff model.…”

Section: Computational Domain and Boundary Conditionsmentioning

confidence: 74%

Numerical investigation into turbulent drag reduction via the application of pufferfish spine-inspired cone microstructures in Suboff models

Zhao,

Zhu,

Feng

et al. 2024

Phys. Scr.

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The effective reduction of seawater drag is pivotal in enhancing the speed and minimizing the energy consumption of submarines, which has significant implications in the fields of energy and defense. Surface bionics has emerged as one of the leading techniques for drag reduction. Current research primarily focuses on replicating the groove-like structures observed on shark skins and the flexible properties of dolphin skins. However, the application of cone microstructures on submarine surfaces remains relatively underexplored. In this study, a novel arrangement of bionic drag-reducing microstructures is employed to modify the turbulence structure surrounding the submarine by incorporating bionic cone microstructures at both the front and rear ends of the submarine. Numerical simulations were performed using the SST k-ω turbulence model to evaluate the impact of these frontal microstructures on drag reduction under varying Reynolds numbers, spacings, and positions, as well as the tail microstructures' effect at different Reynolds numbers, heights, and circumferential separation angles. The findings reveal that positioning microstructures at the submarine's head increases the drag reduction rate proportionally with the distance from the apex, displaying an inverse relationship between spacing and drag reduction rate. Conversely, an increase in cone separation angle at the tail leads to a decrease in the overall drag reduction rate. At the same time, an inverse proportionality is observed between cone height and drag reduction rate. This suggests that cone microstructures play a dual role: mitigating friction drag greatly and augmenting pressure drag, thereby achieving overall drag reduction. Moreover, these cone microstructures disrupt eddy currents within the boundary layer surrounding the submarine, restraining the propagation of turbulent momentum transfer in both the head and tail regions. This research not only pioneers a novel drag reduction strategy for underwater vehicles but also sparks new avenues for their optimized surface design.

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“…For the numerical simulation of synthetic jets, various turbulence modelling approaches such as Reynoldsaveraged Navier-Stokes (RANS) and large eddy simulation (LES) have been employed. [21][22][23][24][25] Although synthetic jets have received a lot of attention in the recent years, sufficiently detailed numerical investigations have not been conducted in this field due to the high computational costs. The capability of turbulence models to accurately simulate the flow field of a turbulent synthetic jet has first been studied by Tang and Zhong.…”

Section: Introductionmentioning

confidence: 99%

Flow Field and Heat Transfer of an Impinging Synthetic Jet in the Presence of Cross-Flow: Application of SAS and DES Approaches

Bazdidi–Tehrani

Saadniya

Rashidzadeh

2021

Proceedings of the Institution of Mechanical Engineers, Part E:

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Nowadays, synthetic jets have various applications such as cooling enhancement and active flow control. In the present paper, the capability of two turbulence modelling approaches in predicting thermal performance of an impinging synthetic jet is investigated. These two approaches are scale adaptive simulation (SAS) and detached eddy simulation (DES). Comparisons between numerical data and experimental studies reveal that the ability of DES in predicting the asymmetrical trend of heat transfer profiles is better than SAS in almost all the study cases. Although, near the stagnation zone, the performance of SAS is superior. Results show that the effects of parameters such as frequency, cross-flow velocity and suction duty cycle factor are well predicted by both approaches. An increase of cross-flow velocity from 1.81 m/s to 2.26 m/s results in an improvement of [Formula: see text] near the stagnation point by almost 16.3% and 9.2% using DES and SAS, respectively.

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Effects of inlet and outlet boundary conditions on the flow field of synthetic jets

Cited by 9 publications

References 25 publications

Investigation of effects of compressibility, geometric and flow parameters on the simulation of a synthetic jet behaviour

Investigation of effects of compressibility, geometric and flow parameters on the simulation of a synthetic jet behaviour

Numerical investigation into turbulent drag reduction via the application of pufferfish spine-inspired cone microstructures in Suboff models

Flow Field and Heat Transfer of an Impinging Synthetic Jet in the Presence of Cross-Flow: Application of SAS and DES Approaches

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