Vortex structures in the wake of a marine propeller operating close to a free surface

Mascio, Andrea Di; Dubbioso, Giulio; Muscari, Roberto

doi:10.1017/jfm.2022.772

Cited by 17 publications

(3 citation statements)

References 32 publications

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“…The motion of the propeller led to a decrease in the elevation of the propeller free surface, primarily at the downstream centerline of the propeller. As the flow developed downstream, the downward effect of the free surface would spread laterally, and the elevation of the free surface downstream of the centerline of the propeller would rise again, which is consisted with the phenomenon observed in the study by Lungu [38] and Di Mascio et al [39]. The shape of the free surface would undergo periodic fluctuations due to the rotation of the propeller, which was more pronounced under the flat inflow condition.…”

Section: Influence Of Propeller Rotation On Free Surfacesupporting

confidence: 60%

A Computational Method for Complex-shaped Hydraulic Turbomachinery Flow Based on Immersed Boundary Method

Li¹,

Feng²,

Zheng³

et al. 2023

Preprint

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Traditional numerical techniques such as sliding mesh, dynamic grid mesh, and others, have many limitations in dealing with flow simulation with large-scale movement of solid boundaries; which is the case for complex-shaped hydraulic turbomachinery such as propellers, pumps and turbines. The immersed boundary (IB) method provides a new approach to solve the above limitations. Therefore, this study proposes an sharp-interface IB method based on the level-set function that is suitable for simulating the flow through turbomachinery with complex geometries. This method is applied to actual three-dimensional numerical simulations of high-Reynolds number propellers using an in-house computational fluid dynamics solver. The results show that the proposed method can provide comparatively accurate predictions of unsteady load coefficients within the propeller flow passage, and capture the correct propeller wake characteristics as well as the interaction between the propeller wake and free surface. This study aims at providing a theoretical basis and engineering reference for the application of the IB method in engineering numerical simulations.

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Section: Influence Of Propeller Rotation On Free Surfacesupporting

confidence: 60%

A Computational Method for Complex-shaped Hydraulic Turbomachinery Flow Based on Immersed Boundary Method

Li¹,

Feng²,

Zheng³

et al. 2023

Preprint

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“…To verify the adequacy of the adopted grid far from the aorta surfaces, where the turbulence model reduces to a large-eddy simulation, the modelled kinetic energy was evaluated and compared with the total energy. To do that, we followed Di Mascio et al [40]. Figure 6 shows the ratio between the modelled kinetic energy and the total kinetic energy on various cross-sections of the aorta geometry for a specific temporal instant (during the systolic phase).…”

Section: Convergence and Grid Sensibility Study: Preliminary Discussionmentioning

confidence: 99%

Blood Flow Simulation of Aneurysmatic and Sane Thoracic Aorta Using OpenFOAM CFD Software

Duronio,

Di Mascio

2023

Fluids

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Cardiovascular diseases still represent one of the most deadly pathologies worldwide. Knowledge of the blood flow dynamics within the cardio-vascular system is crucial in preventing these diseases and analysing their physiology and physio-pathology. CFD simulations are highly effective in guiding clinical predictions and, more importantly, allow the evaluation of physical and clinical parameters that are difficult to measure with common diagnostic techniques. Therefore, in particular, this study is focused on investigating the hemodynamics of the thoracic aorta. Real aortic geometries regarding a sane and diseased patient presenting an aneurysm were considered. CFD simulations were performed with the OpenFOAM C++ library using patient-specific pulsatile blood flow waveforms and implementing the Windkessel pressure boundary condition for the artery outflow. The adopted methodology was preliminarily verified for assessing the numerical uncertainty and convergence. Then, the CFD results were evaluated against experimental data concerning pressure and velocity of the thoracic aorta measured with standard diagnostic techniques. The normal aorta’s blood flow was also compared against the pattern regarding the patient-specific aortic aneurysm. Parameters such as wall pressure, wall shear stress (WSS) and velocity distribution were investigated and discussed. The research highlighted that the blood flow in the aorta is strongly affected by the aneurysm onset, with the growth of recirculation zones being potentially hazardous. The outcomes of the investigation finally demonstrate how CFD simulation tools, capturing the detailed physics of the aortic flow, are powerful tools for supporting clinical activities of the cardio-vascular system.

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“…DES was employed to contrast the propeller vortex formation under different conditions, using numerical evaluation. Vortex topologies were exposed under different loading conditions, and they demonstrated that the pronounced interference effects led to the premature collapse of the vortex system, thereby preventing the tip vortex pairing process from occurring [27]. In their study, Posa [28] replicated the wake produced at distinct propulsive coefficients based on the LES method.…”

Section: Introductionmentioning

confidence: 99%

Influence of Load Conditions on the Propeller Wake Evolution

Yu,

Wang,

Liu

et al. 2023

JMSE

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The present work presents numerical research on the wake flows behind a propeller operating under three advance coefficients. Large eddy simulations are adopted to obtain the viscous flow information behind the propeller. In particular, the study highlights the comparison of the evolution characteristics and the flow physics within the propeller wakes with three advance coefficients. The predicted global force and moment coefficients and phase-average statistics of streamwise velocity agree well with the available experimental data. Compared to all other flow structures in the wake, the tip vortices are found to play the most significant role according to the results. During the pairing process of adjacent tip vortices, the tip vortices diffuse circumferentially, leading to enhanced mutual-induction effects. When the advance coefficient is low, the wake becomes distorted, and the pairing process takes place in the middle region of the flow field. As a result of their unstable motion, the four tip vortices generated by the propeller cannot be distinguished individually in the far field. Instead, they break down into smaller vortices and tend to distribute themselves uniformly in the azimuthal direction. The increase in the advance coefficient delays the pairing process. This study offers valuable insights for the design and optimization of marine propellers.

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Vortex structures in the wake of a marine propeller operating close to a free surface

Cited by 17 publications

References 32 publications

A Computational Method for Complex-shaped Hydraulic Turbomachinery Flow Based on Immersed Boundary Method

A Computational Method for Complex-shaped Hydraulic Turbomachinery Flow Based on Immersed Boundary Method

Blood Flow Simulation of Aneurysmatic and Sane Thoracic Aorta Using OpenFOAM CFD Software

Influence of Load Conditions on the Propeller Wake Evolution

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