Effects of Turbulence Model and Numerical Time Steps on Von Karman Flow Behavior and Drag Accuracy of Circular Cylinder

Amalia, Ema; Moelyadi, Mochammad Agoes; Ihsan, Muhammad

doi:10.1088/1742-6596/1005/1/012012

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…In this case, a proper turbulence model is the k-ω, since it allows a direct integration to the wall without having to subdivide the flow domain into low-and high-Reynolds-number regions as required by the k-ε turbulence model [10]. Although the SST (Shear Stress Transport) formulation of the k-ω turbulence models has also proved to be valid in the evaluation of the von Karman shedding phenomena [11], a hybrid URANS-scale resolved approach with SAS-SST (Scale Adaptive Simulation-Shear Stress Transport) was preferred for this study. In fact, as reported by Neumann et al [4], the SAS turbulent model has been proven to give good accuracy in frequency prediction, and it results in more realistic force amplitudes compared with other two-equation turbulence models such as the SST.…”

Section: The Numerical Modelmentioning

confidence: 99%

Effect of the von Karman Shedding Frequency on the Hydrodynamics of a Francis Turbine Operating at Nominal Load

Zanetti

Cavazzini

Santolin

2023

IJTPP

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This paper presents a numerical analysis of the influence of the von Karman vortex shedding at the blade trailing edge on the hydrodynamics of a recently installed small hydro Francis turbine manifesting very loud and high-frequency acoustic pulsations when operating close to the nominal load. A reduced single-passage numerical model is developed to reduce the computational effort of the simulation while ensuring high accuracy in the assessment of fluid flow. The accuracy of the proposed numerical approach is investigated by comparing the frequency spectrum of the experimentally acquired acoustic frequency and the numerical pressure signals, confirming the nature of the machine’s vibrations. The validated numerical model represents a useful tool for an in-depth analysis of the machine’s hydrodynamics in the preliminary design phases. The proposed approach represents a valid alternative to the traditional correlation-based approach for the evaluation of the von Karman shedding frequency with less computational effort compared with a transient simulation of the entire machine.

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Section: The Numerical Modelmentioning

confidence: 99%

Effect of the von Karman Shedding Frequency on the Hydrodynamics of a Francis Turbine Operating at Nominal Load

Zanetti

Cavazzini

Santolin

2023

IJTPP

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“…The numerical results agreed further with the experimental findings. Amalia et al [25] identified the best turbulence model by analyzing the flow in a circular cylinder and the impact of time-step size on the flow. According to their findings, the optimal outcome can be achieved with the SST k-ω turbulence model for 2D case and time-step between 0.00025 s and 0.004 s is preferred.…”

Section: Introductionmentioning

confidence: 99%

Drag Reduction for Flow Past Circular Cylinder Using Static Extended Trailing Edge

Boral

Dutta

Das

et al. 2023

ASME Open Journal of Engineering

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A numerical study has been carried out on the two-dimensional flow past a circular cylinder. In this case, a splitter plate is provided at the rear stagnation point in the downstream direction. ansys fluent has been used to carry out the numerical simulations based on finite volume method approach. Grid independence was achieved and the numerical model was validated with results available in open literature at Reynolds numbers of 100, 5000, and 100,000 respectively. In the present investigation, the characteristics of vortex shedding due to the presence of splitter plate in the circular cylinder were investigated. The main focus of this research was to find the optimal splitter plate length for low, moderate, and high Reynolds numbers. It was observed that at low, moderate, and high Reynolds numbers, the drag coefficient (cd) for optimal plate length decreased drastically as compared to the baseline circular cylinder case. Moreover, the fluctuating nature of lift coefficient (cl) had also ceased. This research work has a good potential to decrease time-varying structural loads on bluff bodies by decreasing the vortex shedding frequency and consequently decreasing drag. The scope of our research extends to structures of bridges and large vehicles, radiator pipes of heat exchangers, landing gears of aircraft, and many more.

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Mask Video Projection-Based Stereolithography With Continuous Resin Flow

Mao

Pan

et al. 2019

Journal of Manufacturing Science and Engineering

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The mask image projection-based stereolithography (MIP-SL) is a low-cost and high-resolution additive manufacturing (AM) process. However, the slow speed of part separation and resin refilling is the primary bottleneck that limits the fabrication speed of the MIP-SL process. In addition, the stair-stepping effect due to the layer-based fabrication process limits the surface quality of built parts. To address the critical issues in the MIP-SL process related to resin refilling and layer-based fabrication, we present a mask video projection-based stereolithography (MVP-SL) process with continuous resin flow and light exposure. The newly developed AM process enables the continuous fabrication of three-dimensional (3D) objects with ultra-high fabrication speed. In the paper, the system design to achieve mask video projection and the process settings to achieve ultrafast fabrication speed are presented. The relationship between process parameters and the surface quality of the built parts is discussed. Test results illustrate that the MVP-SL process with a continuous resin flow can build three-dimensional objects within minutes, and the surface quality of the fabricated objects is significantly improved.

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Effects of Turbulence Model and Numerical Time Steps on Von Karman Flow Behavior and Drag Accuracy of Circular Cylinder

Cited by 3 publications

References 2 publications

Effect of the von Karman Shedding Frequency on the Hydrodynamics of a Francis Turbine Operating at Nominal Load

Effect of the von Karman Shedding Frequency on the Hydrodynamics of a Francis Turbine Operating at Nominal Load

Drag Reduction for Flow Past Circular Cylinder Using Static Extended Trailing Edge

Mask Video Projection-Based Stereolithography With Continuous Resin Flow

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