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Hydrodynamics of Euglena Gracilis during locomotion J. Hydrodyn. (IF 2.265) Pub Date : 2021-02-24 Fahrettin Gökhan Ergin
The hydrodynamics and locomotion mechanism of Euglena Gracilis (E. Gracilis) is investigated using microscopic shadow imaging and micro particle image velocimetry (MicroPIV). Three distinct locomotion modes were observed: translation, spin, and left/right turn. Since the flagellum was not possible to image, the strokes were identified by evaluating the flow field around the protist. The flow field
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Experimental and numerical investigations of cavitation evolution in a high-speed centrifugal pump with inducer J. Hydrodyn. (IF 2.265) Pub Date : 2021-02-05 Yu-ying Huan, Yao-yao Liu, Xiao-jun Li, Zu-chao Zhu, Jing-tian Qu, Lin Zhe, An-da Han
Along with the anti-cavitation performance, the high speed and the high power density, are the main trends in the development of centrifugal pumps. At present, the most effective method is to install an inducer in front of the impeller. However, the tip leakage of the inducer results in the vortex cavitation at the blade leading edge of the inducer, and the cavitating flow inside the inducer seriously
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Numerical analysis of fluid flow dynamics around a yawed half-submerged cylinder inside an open channel J. Hydrodyn. (IF 2.265) Pub Date : 2021-02-04 M. I. Alamayreh, A. Fenocchi, G. Petaccia, S. Sibilla, E. Persi
The drag and side force coefficients of a half-submerged cylinder in a free-surface flow were calculated through numerical simulations, with the aim of supporting the numerical modelling of log transport in rivers. The variability of these coefficients with the yaw angle with respect to the flow direction and with the ratio between the flow depth and the diameter of the cylinder were investigated.
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Experimental study of droplet behavior in a swirl flow field induced by two kinds of guiding vanes and inlet structure optimization J. Hydrodyn. (IF 2.265) Pub Date : 2021-02-04 Shi-ying Shi, Huan-qiang Sun, Li-ming Lin, Cheng-fu Zhang, Jian Zhang
Droplet breakage is a common phenomenon in converting a pipe flow to a swirl flow in a vane-type pipe separator (VTPS)’ inlet. The evaluation of the dispersed droplet sizes after breakage is crucial to the optimum design of the inlet structure and the estimation of the oil-water separation performance. This paper studies the droplet behavior in a swirl flow produced by guiding vanes. Experiments are
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A new method of LES verification and validation for attached turbulent cavitating flow J. Hydrodyn. (IF 2.265) Pub Date : 2021-02-04 Yun Long, Lin-feng Deng, Jun-qiang Zhang, Bin Ji, Xin-ping Long
The large eddy simulation (LES) is used to resolve the flow structure in the cavitating turbulent flow around the Clark-Y hydrofoil coupled with a homogeneous cavitation model. A new method is proposed in this paper to calculate the LES error of the time-averaged streamwise velocity for the LES verification and validation (V&V). From the instantaneous cavity patterns, it is demonstrated that the predicted
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Analysis of dipole noise level characteristics of NACA0015 hydrofoil under different working conditions J. Hydrodyn. (IF 2.265) Pub Date : 2021-02-04 An Yu, Yi-fu Wang, Qing-hong Tang, Da-qing Zhou
In this paper, the flow field around NACA0015 hydrofoil is calculated under the condition of two-phase cavitating flow to provide a theoretical guidance for reducing the cavitation noise. A modified turbulence model coupled with the Zwart cavitation model is used to calculate the flow field. According to the computed sound source data, the dipole sound pressure distribution diagrams for the extremely
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Acoustics of a viscoelastic medium with encapsulated bubbles J. Hydrodyn. (IF 2.265) Pub Date : 2021-02-04 Damir A. Gubaidullin, Yuri V. Fedorov
In this paper, a modified Rayleigh-Lamb equation is derived that takes into account the radial vibrations of a gas bubble coated with a viscoelastic shell and located in an elastic medium. For small oscillations of inclusion, the problem of heat exchange between a gas, a liquid phase, a viscoelastic shell, and an elastic medium is solved. The energy integral is determined. In the case of small disturbances
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Numerical investigation on the drag force of a single bubble and bubble swarm J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-08 Ling-xin Zhang, Ze-cai Zhou, Xue-ming Shao
The bubble drag force correlation plays an important role in the numerical simulation accuracy of gas/liquid flows. In order to systematically investigate the interphase drag force of non-buoyancy driven bubbly flows, a dynamic-positioning body force (DPBF) method is developed in this study. It is proved that this method has an enough computation precision. Using this method, a series of direct numerical
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Liutex-based vortex dynamics: A preliminary study J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-28 Hai-dong Yu, Yi-qian Wang
Vortex dynamics, with the possibility of efficient flow control, is explored in this study based on the new introduced vortex definition and identification system of Liutex. With the six core elements of vortex identification, including (1) absolute strength, (2) relative strength, (3) local rotational axis, (4) global rotational axis, (5) vortex core size and (6) vortex boundary, provided by the Liutex
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Flow characteristics in open channels with aquatic rigid vegetation J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-02 Yan-jie Wu, He-fang Jing, Chun-guang Li, Ying-ting Song
In order to study the flow characteristics in water bodies with rigid aquatic vegetation, series of laboratory experiments are carried out in an open channel, in which glass rods are used as plants with diameters of 6mm, 8mm and 10mm, respectively. For each diameter of glass rods, four typical cases are considered with various densities and arrangements of glass rods. The flow velocities in the four
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The flow characteristics around bridge piers under the impact of a ship J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-28 Yan-fen Geng, Hua-qiang Guo, Xing Ke
The complicated flow structure around the pier threatens the safe navigation of ships. This paper studies the mechanism of the flow with a ship around the pier, passing or not passing and with consideration of the interval between the ship and the pier. The flow field model and the moving ship model are constructed by the six degrees of freedom (6DOF) solver combined with the virtual unit immersed
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Numerical study on the bubble dynamics in a broken confined domain J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-28 Hao Tang, Yun-Long Liu, Pu Cui, A.-Man Zhang
In this paper, the dynamic characteristics of the bubble in a broken confined domain are studied. The broken confined domain is composed of a solid wall and a plate that has a hole. The axisymmetric numerical model is established by combining the Eulerian finite-element method with volume of fluid (VOF) method, and is validated by comparing the results with those from an experiment. Then the influences
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Numerical investigation on the drag force of a single bubble and bubble swarm J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-08 Ling-xin Zhang, Ze-cai Zhou, Xue-ming Shao
The bubble drag force correlation plays an important role in the numerical simulation accuracy of gas/liquid flows. In order to systematically investigate the interphase drag force of non-buoyancy driven bubbly flows, a dynamic-positioning body force (DPBF) method is developed in this study. It is proved that this method has an enough computation precision. Using this method, a series of direct numerical
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The effects of caudal fin deformation on the hydrodynamics of thunniform swimming under self-propulsion J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-28 Yi-kun Feng, Yu-min Su, Huan-xing Liu, Yuan-yuan Su
To investigate the effects of the caudal fin deformation on the hydrodynamic performance of the self-propelled thunniform swimming, we perform fluid-body interaction simulations for a tuna-like swimmer with thunniform kinematics. The 3-D vortices are visualized to reveal the role of the leading-edge vortex (LEV) in the thrust generation. By comparing the swimming velocity of the swimmer with different
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Numerical simulation of the effect of waves on cavity dynamics for oblique water entry of a cylinder J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-28 Gui-yong Zhang, Zhao Hou, Tie-zhi Sun, Hai-peng Wei, Ning Li, Bo Zhou, Ying-jie Gao
The water entry process associated with complicated unsteady structures, with consideration of the influence of the waves, is not well studied. In the present work, the oblique water entry of a cylinder under different regular waves is numerically investigated. The volume of fluid (VOF) method and the sub-grid scale (SGS) stress model based on the large eddy simulation (LES) method are adopted for
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Liutex core line and POD analysis on hairpin vortex formation in natural flow transition J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-28 Sita Charkrit, Pushpa Shrestha, Chaoqun Liu
In this study, the new method of the vortex core line based on Liutex definition, also known as Liutex core line, is applied to support the hypothesis that the vortex ring is not a part of the Λ - vortex and the formation of the ring-like vortex is formed separately from the Λ - vortex. The proper orthogonal decomposition (POD) is also applied to analyze the Kelvin-VHelmholtz (K-H) instability happening
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Numerical investigation of alleviation of undesirable effect of inter-blade vortex with air admission for a low-head Francis turbine J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-28 Long-gang Sun, Peng-cheng Guo, Luo-chang Wu
In order to compensate for the stochastic nature of the power grid due to the tremendous development and the integration of renewable energy resources and meet its other requirements, the hydraulic turbines are forced to operate more frequently under partial load conditions with singular and misaligned flows inevitably excited by the inter-blade vortex. This paper presents numerical investigations
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Applying physics informed neural network for flow data assimilation J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-10 Xiao-dong Bai, Yong Wang, Wei Zhang
Data assimilation (DA) refers to methodologies which combine data and underlying governing equations to provide an estimation of a complex system. Physics informed neural network (PINN) provides an innovative machine learning technique for solving and discovering the physics in nature. By encoding general nonlinear partial differential equations, which govern different physical systems such as fluid
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Control of water contamination on side window of road vehicles by A-pillar section parameter optimization J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-07 Li Xin, Xing-jun Hu, Jing-yu Wang
The water contamination on the side windows of moving vehicles is a crucial issue in improving the driving safety and the comfort. In this paper, an effective optimization method is proposed to reduce the water contamination on the side windows of automobiles. The accuracy and the efficiency of the numerical simulation are improved by using the lattice Boltzmann method, and the Lagrangian particle
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Lagrangian analysis of the fluid transport induced by the interaction of two co-axial co-rotating vortex rings J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-07 Hai-yan Lin, Yang Xiang, Su-yang Qin, Hui Xu, Hong Liu
In this paper, the fluid transport in the interaction of two co-axial co-rotating vortex rings are investigated. Vortex rings are generated using the piston-cylinder apparatus, and the resulting velocity fields are measured using digital particle image velocimetry. The interaction process is analysed by means of vorticity contour, as well by investigation of the Lagrangian coherent structures (LCSs)
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Experimental analysis of tip vortex cavitation mitigation by controlled surface roughness J. Hydrodyn. (IF 2.265) Pub Date : 2020-12-02 Urban Svennberg, Abolfazl Asnaghi, Robert Gustafsson, Rickard E. Bensow
This study presents results of experiments where roughness applications are evaluated in delaying the tip vortex cavitation inception of an elliptical foil. High-speed video recordings and laser doppler velocimetry (LDV) measurements are employed to provide further details on the cavitation behavior and tip vortex flow properties in different roughness pattern configurations. The angular momentum measurements
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Numerical simulations of propeller cavitation flows based on OpenFOAM J. Hydrodyn. (IF 2.265) Pub Date : 2020-11-26 Min-sheng Zhao, Wei-wen Zhao, De-cheng Wan
In order to study the cavitation and hydrodynamic characteristics of propeller under uniform and non-uniform flows, numerical investigations are performed using interPhaseChangeDyMFoam in the open source computational fluid dynamics (CFD) software platform OpenFOAM with Schnerr-Sauer cavitation model. The simulation results can be used as a reference to evaluate the working ability of a propeller in
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Local scour by multiple slit-type energy dissipaters J. Hydrodyn. (IF 2.265) Pub Date : 2020-11-23 Li Yao, Jian-hua Wu
Energy dissipation and scour control are all the key issues for the design of hydraulic structures. On the basis of the high energy dissipation for the multiple slit-type energy dissipaters (M-STED) developed by the authors, in this work, the characteristics of the scour hole for the M-STED were experimentally investigated through three sets of those physical models with five cases and a scour hole
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LES method of the tip clearance vortex cavitation in a propelling pump with special emphasis on the cavitation-vortex interaction J. Hydrodyn. (IF 2.265) Pub Date : 2020-11-23 Cheng-zao Han, Shun Xu, Huai-yu Cheng, Bin Ji, Zhi-yuan Zhang
The turbulent cavitating flow around the propelling pump tip clearance is numerically simulated using the large eddy simulation (LES) method coupled with the Zwart-Gerber-Belamri (ZGB) cavitation model to investigate the cavitation-vortex interaction mechanism. The calculated cavitation structures around the blades are in a remarkable agreement with the experimental results. The distributions of the
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Correlation analysis among vorticity, Q method and Liutex J. Hydrodyn. (IF 2.265) Pub Date : 2020-11-23 Yifei Yu, Pushpa Shrestha, Oscar Alvarez, Charles Nottage, Chaoqun Liu
Influenced by the fact that vorticity represents rotation for rigid body, people believe this idea also works for fluid flow. However, the vortex predictions by vorticity do not match experimental results, which drove scientists to look for more appropriate methods to identify vortex. All vortex identification methods can be categorized into three generations. The vorticity-based method is classified
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Control of vortex-induced vibrations of the cylinder by using split-ter plates immersed in the cylinder wake at low Reynolds number J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Zhi-qiang Xin, Zhi-huang Wu, Chui-jie Wu, Dan Huang
The vortex-induced vibrations of a cylinder with two plates symmetrically distributed along the centerline of the wake are studied by using the fluid-structure interaction simulations on the Arbitrary Lagrangian-Eulerian method. In this study, the different geo-metrical distribution parameters of the splitter plates and inflow velocities are taken into account. The physical mechanisms of vortex-induced
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Numerical analysis of added mass and damping of elastic hydrofoils J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Jia-sheng Li, Ye-gao Qu, Hong-xing Hua
A numerical model is proposed for analyzing the effects of added mass and damping on the dynamic behaviors of hydrofoils. Strongly coupled fluid-structure interactions (FSIs) of hydrofoils are analyzed by using the 3-D panel method for the fluid and the finite element method for the hydrofoils. The added mass and damping matrices due to the external fluid of the hydrofoil are asymmetric and computational
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Numerical investigations of the transient cavitating vortical flow structures over a flexible NACA66 hydrofoil J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Ren-fang Huang, Te-zhuan Du, Yi-wei Wang, Cheng-guang Huang
In this paper, the cavitating flow over a flexible NACA66 hydrofoil is studied numerically by a modified fluid-structure interaction strategy with particular emphasis on understanding the flow-induced vibration and the cavitating vortical flow structures. The modified coupling approaches include (1) the hydrodynamic solution obtained by the large eddy simulation (LES) together with a homogenous cavitation
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Physical properties of vortex and applicability of different vortex identification methods J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Pei-qing Liu, Yue Zhao, Qiu-lin Qu, Tian-xiang Hu
For correct identification of vortices, this paper first analyzes the properties of the rigid vortex core and its induced flow field given by the Rankine vortex model, and it is concluded that the concentrated vortex structure should consist of the vortex core and the induced flow field (the potential flow region with a weak shear layer). Then the vortex structure is analyzed by using the Oseen vortex
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An experiment study of vortex induced vibration of a steel catenary riser under steady current J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Tie Ren, Yu-wang Xu, Jungao Wang, Hao-jie Ren, Meng-meng Zhang, Shi-xiao Fu, Yao-song Chen
The vortex induced vibration (VIV) of marine risers has been investigated by many researchers in experimental studies of a straight flexible riser model as well as a rigid cylinder to reveal the dynamic response characteristic and the mechanics behind it. However, due to the limitation of experimental apparatus, very few studies are about the VIV of a steel catenary riser (SCR) which is with a complex
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Investigation on subsurface vortices within a closed pump intake under different pressure conditions J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Miao Guo, Xue-lin Tang, Xiao-qin Li, Fu-jun Wang, Xiao-yan Shi
An experimental study to investigate various features of subsurface vortices and their evolutions inside a closed pump intake under different pressure conditions at free surface, and to analyze the influence of a pipe bell with different mean axial velocities at the same water level on flow patterns is presented. For all cases, three different flow regimes are closely observed: various side-wall attached
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Oxygen transfer characteristics of bubbly jet in regular waves J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Ze-gao Yin, De-chun Liu, Yuan Li, Yan-xu Wang
The dissolved oxygen level is an important index of the water environment, and in this paper, the oxygen transfer of the bubbly jet in regular waves is investigated numerically and experimentally. The Reynolds-averaged Navier-Stokes equations, the re-normalisation group k-ε equations, and the volume of fluid (VOF) technique are used along with a 2-D CFD model to simulate the wave and bubble motions
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Experimental and CFD investigations of choked cavitation characteristics of the gap flow in the valve lintel of navigation locks J. Hydrodyn. (IF 2.265) Pub Date : 2020-10-29 Bo Wu, Ya-an Hu, Xin Wang, Xiu-jun Yan
The cavitation is ubiquitous in the water delivery system of high hydraulic head navigation locks. This paper studies the choked cavitation characteristics of the gap flows in the valve lintel of the navigation locks and analyzes the critical self-aeration conditions. The cavitation gap flow in the valve lintel is experimentally and numerically investigated. A visualized 1:1 full-scale slicing model
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Liutex-based analysis of drag force and vortex in two-phase flow past 2-D square obstacle using LBM on GPU J. Hydrodyn. (IF 2.265) Pub Date : 2020-09-29 Peng-xin Cheng, Nan Gui, Xing-tuan Yang, Ji-yuan Tu, Sheng-yao Jiang, Hai-jun Jia
The two-phase flow past a square is a ubiquitous phenomenon widely encountered in industries and engineering, where the interaction of disparate phases coupled with the influence of the solid is rather complicated. In this context, the flow characteristics and the vortex field are investigated to reveal the mechanisms of the two-phase drag and the vortex variation. The lattice Boltzmann method (LBM)
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A numerical study of the early-stage dynamics of a bubble cluster J. Hydrodyn. (IF 2.265) Pub Date : 2020-09-23 Ya-zhen Shi, Kai Luo, Xiao-peng Chen, Dai-jin Li
The dynamics of multiple cavitating bubbles is numerically simulated, with the ambient pressure lower than the saturated vapor pressure, using a pseudopotential lattice Boltzmann method (LBM) coupled with the Carnahan-Starling equation of state. Dual-bubble and multi-bubble systems are tested, and the method for the bubble cluster is validated. It is found that the bubble can either grow or collapse
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Experimental study on dynamic mechanism of vortex evolution in a turbulent boundary layer of low Reynolds number J. Hydrodyn. (IF 2.265) Pub Date : 2020-09-21 Yan-ang Guo, Xiang-rui Dong, Xiao-shu Cai, Wu Zhou
The dynamic mechanism of the vortex generation and evolution process in a fully developed turbulent boundary layer with Re0 = 97–194 is experimentally investigated. In this study, a moving single-frame and long-exposure (MSFLE) imaging method and a moving particle image velocimetry/particle tracing velocimetry (M-PIV/PTV) are designed and implemented for measuring the temporal and spatial evolution
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A numerical investigation of interactions between extreme waves and a vertical cylinder J. Hydrodyn. (IF 2.265) Pub Date : 2020-09-15 Qun-bin Chen, Yu-xiang Ma, Guo-hai Dong, Xiao-zhou Ma, Bing Tai, Xu-yang Niu
In this paper, the interactions between extreme waves and a vertical cylinder are investigated through a 3-D two-phase flow model. The numerical model is verified and validated by experimental data. Then, two factors are considered, the global wave steepness and the frequency bandwidth of the wave groups, in the studies of the in-line wave forces and the wave run-up around a cylinder. It is found that
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On the initial values of kinematic and dynamic free-surface boundary conditions for water wave problems J. Hydrodyn. (IF 2.265) Pub Date : 2020-09-03 Dong-qiang Lu
The kinematic and dynamic boundary conditions on the free surface of a fluid should be posed for water wave problems. In the framework of potential theory for an inviscid and incompressible fluid with an irrotational motion, the combined boundary condition, which involves the velocity potential only, is often used by eliminating the elevation terms mathematically. Such a combination is correct for
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On solitary wave in nonuniform shear currents J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-26 Zhan Wang; Bin-bin Zhao; Wen-yang Duan; R. Cengiz Ertekin; Masoud Hayatdavoodi; Tian-yu Zhang
In this paper, steady solutions of solitary waves in the presence of nonuniform shear currents are obtained by use of the high-level Green-Naghdi (HLGN) model. We focus on large-amplitude solitary waves in strong opposing shear currents. The linear-type currents, quadratic-type currents and cubic-type currents are considered. In particular, the wave speed, wave profile, velocity field, particle trajectories
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A novel Omega-driven dynamic PANS model J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-26 Chao-yue Wang; Fu-jun Wang; Ben-hong Wang; Yuan Tang; Hao-ru Zhao
A novel Omega (Ω) -driven dynamic partially-averaged Navier-Stokes (PANS) model is proposed in this paper. The ratio of the modeled-to-total turbulent kinetic energies fk is dynamically adjusted by the rigid vorticity ratio (the ratio of the rigid vorticity to the total vorticity), the key parameter of the Ω vortex identification method. Three classical flow cases with rotation and curvature are used
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Fission law of solitary waves propagating over sharply variable topography J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-26 Da-lin Tan; Ji-fu Zhou; Xu Wang
The fission of solitary waves propagating over variable topography is investigated. In previous theories, to predict the number and the amplitudes of disintegrated solitons in the wave packet generated from a solitary wave, the parameters of the water environment and the incident solitary wave are required. However, it is difficult to measure these parameters in the ocean because of their temporal
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A TensorFlow-based new high-performance computational framework for CFD J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-26 Xi-zeng Zhao; Tian-yu Xu; Zhou-teng Ye; Wei-jie Liu
In this study, a computational framework in the field of artificial intelligence was applied in computational fluid dynamics (CFD) field. This Framework, which was initially proposed by Google AI department, is called “TensorFlow”. An improved CFD model based on this framework was developed with a high-order difference method, which is a constrained interpolation profile (CIP) scheme for the base flow
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Effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-26 Ning Zhang; Bo Gao; Bin Xia; Qi-feng Jiang
The volute tongue, as the crucial component inducing rotor-stator interaction, is detrimental to unsteady pressure pulsations of centrifugal pumps. In the present paper, to investigate the effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump, three volute tongues are obtained through twice cuts, named cases 1, 2, 3. Twenty measuring points are evenly mounted
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Development and application of a new random walk model to simulate the transport of degradable pollutants J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-26 Lin Zhang; Li-na Chen; Jian-yin Zhou; Jia-sheng Wang; Qi-hong Yang; Long-xi Han
To simulate the pollutant transport with self-purification in inland waters, the widely used random walk model (RWM) is modified to include a source term for the degradation and to consider the impact of land boundaries. The source term for the degradation is derived from the assumption of the first-order reaction kinetics. Parameters for the new model are determined by a comparison to the analytical
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On the development of ice-water-structure interaction J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-14 Bao-yu Ni; Duan-feng Han; Shao-cheng Di; Yan-zhuo Xue
Ice-water-structure interaction (IWSI) is a novel extension of the fluid-structure interaction (FSI), which is significant for design and operating of polar ship and offshore structures. It involves multi-media and multi-interfaces and thus is quite complicated to solve, no matter from mathematical or mechanical perspectives. Although IWSI is complex and still very new, researchers try to develop various
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Experimental investigation of regular wave propagation over an idealized reef model J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-14 Gan-cheng Zhu; Bing Ren; Hong-jie Wen; Guo-yu Wang; Yong-xue Wang
The wave transformation over the deep-sea coral reefs is an essential issue in the analysis of the reef ecosystem and the design of large reef-top structures. Extensive wave flume experiments are conducted to investigate the wave transformation processes over an idealized reef model. Detailed measurements of the wave height, the wave set-up and the wave-generated flow on the reef-top are made with
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Simulations of helicopter ditching using smoothed particle hydrodynamics J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-10 G. Oger; A. Vergnaud; B. Bouscasse; J. Ohana; M. Abu Zarim; M. De Leffe; A. Bannier; L. Chiron; Y. Jus; M. Garnier; S. Halbout; D. Le Touzé
The present work has been performed in the context of the European H2020 project increased SAfety and Robust certification for ditching of Aircrafts and Helicopters (SARAH) dedicated to improving the safety during aircraft ditching, together with a better understanding of the physics involved during those crucial events. Both numerical and experimental aspects are explored during this project. The
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New instability and mixing simulations using SPH and a novel mixing measure J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-10 Georgina Reece; Benedict D. Rogers; Steven Lind; Georgios Fourtakas
This paper assesses the ability of smoothed particle hydrodynamics (SPH) to simulate mixing of two-phase flows and their transition to instabilities under different flow regimes. A new measure for quantification of the degree of mixing between phases in a Lagrangian framework is also developed. The method is validated using the lid-driven cavity and two-phase Poiseuille flow cases. The velocity along
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On the numerical solution to the truncated discrete SPH formulation of the hydrostatic problem J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-06 Pablo Eleazar Merino-Alonso; Fabricio Macià; Antonio Souto-Iglesias
The aim of this work is to study the solution of the smoothed particle hydrodynamics (SPH) discrete formulation of the hydrostatic problem with a free surface. This problem, in which no time dependency is considered, takes the form of a system of linear equations. In particular, the problem in one dimension is addressed. The focus is set on the convergence when both the particle spacing and the smoothing
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Some notes on numerical simulation of the turbulent cavitating flow with a dynamic cubic nonlinear sub-grid scale model in OpenFOAM J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-06 Zi-yang Wang; Xian-bei Huang; Huai-yu Cheng; Bin Ji
The accuracy of large eddy simulation (LES) is highly dependent on the performance of sub-grid scale (SGS) model. In the present paper, a dynamic cubic nonlinear sub-grid scale model (DCNM) proposed by Huang et al. is implemented for the simulation of unsteady cavitating flow around a 3-D Clark-Y hydrofoil in OpenFOAM. Its performance in predicting the evolution of cloud cavitation is discussed in
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Incompressible SPH simulation of solitary wave propagation on permeable beaches J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-06 Chiaki Tsurudome; Dongfang Liang; Yuma Shimizu; Abbas Khayyer; Hitoshi Gotoh
Wave propagation on uniformly sloped beaches is a canonical coastal engineering topic that has been studied extensively in the past few decades. However, most of these studies treat beaches as solid boundaries even though they are often made of porous materials, such as sediment and vegetation. Permeable beaches struck by tsunami-like waves have not been adequately investigated. It is expected that
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Predictions of bulk velocity for open channel flow through submerged vegetation J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-06 Wei-jie Wang; Xiao-yu Cui; Fei Dong; Wen-qi Peng; Zhen Han; Ai-ping Huang; Xue-kai Chen; Yuan Si
Vegetation is of great significance in river ecosystems in terms of hydrodynamics, water environment and ecology. The question of how to predict the bulk velocity in channel flow through submerged vegetation is currently a hot topic in hydraulics research. The present study addresses this question. The various formulae used for bulk velocity estimation in previous work were reviewed and compared. The
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CFD simulations of three-dimensional violent sloshing flows in tanks based on MPS and GPU J. Hydrodyn. (IF 2.265) Pub Date : 2020-08-04 Feng-ze Xie; Wei-wen Zhao; De-cheng Wan
For violent sloshing, the flow field becomes complicated and 3-D effect is non-negligible. In addition to the excitation direction, the wave can also propagate perpendicular to the excitation direction. Due to the superposition of waves from different directions, the impact pressure imposed on the wall of the tank may increase. In this paper, our in-house solver MPSGPU-SJTU based on moving particle
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The hydraulic performance of twin-screw pump J. Hydrodyn. (IF 2.265) Pub Date : 2020-06-30 Di Zhang; Li Cheng; Ying-yuan Li; Wei-xuan Jiao
Based on the computational fluid dynamics (CFD) and the experiment technology, this paper presents a new type of the twin-screw pump for the water-supply and studies its hydraulic performance with the hydraulic performance test. The internal flow characteristics and the hydraulic performance of the twin-screw pump are numerically simulated. The CFD results show that at different heads, the screw pressure
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POD analysis on vortical structures in MVG wake by Liutex core line identification J. Hydrodyn. (IF 2.265) Pub Date : 2020-06-28 Xiang-rui Dong; Xiao-shu Cai; Yinlin Dong; Chaoqun Liu
The Liutex core line method, first combined with the snapshot proper orthogonal decomposition (POD), is utilized in a supersonic micro-vortex generator (MVG) wake flow at Ma = 2.5 and Reθ = 5 760 to reveal the physical significance of each POD mode of the flow field. Compared with other scalar-based vortex identification methods, the Liutex core line identification is verified to be the most appropriate
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Estimation of the turbulent viscous shear stress in a centrifugal rotary blood pump by the large eddy particle image velocimetry method J. Hydrodyn. (IF 2.265) Pub Date : 2020-06-22 Jing-jing Ji; Hao-yuan Li; Qing-yu Wu; Yu Zhang; Xian-wu Luo
The non-physiologic turbulent flows in centrifugal rotary blood pumps (RBPs) may result in complications such as the hemolysis and the platelet activation. Recent researches suggest that the turbulent viscous dissipation in the smallest eddies is the main factor of the blood trauma caused by the turbulent flow. The turbulent viscous shear stress (TVSS) was taken as the realistic physical force acting
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Principal coordinates and principal velocity gradient tensor decomposition J. Hydrodyn. (IF 2.265) Pub Date : 2020-06-22 Yifei Yu; Pushpa Shrestha; Charles Nottage; Chaoqun Liu
Helmholtz velocity decomposition and Cauchy-Stokes tensor decomposition have been widely accepted as the foundation of fluid kinematics for a long time. However, there are some problems with these decompositions which cannot be ignored. Firstly, Cauchy-Stokes decomposition itself is not Galilean invariant which means under different coordinates, the stretching (compression) and deformation are quite
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A study of the evolution of nanoparticle dynamics in a homogeneous isotropic turbulence flow via a DNS-TEMOM method J. Hydrodyn. (IF 2.265) Pub Date : 2020-06-12 Hong-ye Ma, Ming-zhou Yu, Han-hui Jin
In this article, a coupling of the direct numerical simulation (DNS) and the population balance modeling (PBM) is implemented to study the effect of turbulence on nanoparticle dynamics in homogenous isotropic turbulence (HIT). The DNS is implemented based on a pseudo-spectral method and the PBM is implemented using the Taylor-series expansion method of moments. The result verifies that coagulation
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Experimental study of an ellipsoidal particle in tube Poiseuille flow J. Hydrodyn. (IF 2.265) Pub Date : 2020-06-12 Yuan-feng Cui; Xiang-ting Chang; Hai-bo Huang
Behaviors of a prolate ellipsoid inside circular tube Poiseuille flow are studied experimentally. In the study, Reynolds number Re ∈ (100,700) and the confinement ratio D/A ∈ (1.2,2.8) are considered, where D is the diameter of the tube and A is the length of the major axis of the ellipsoid. Two typical stable motion modes are identified, namely, the horizontal, and inclined modes. Then another inclined
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A review on flow-induced vibration of offshore circular cylinders J. Hydrodyn. (IF 2.265) Pub Date : 2020-06-08 Jia-song Wang; Dixia Fan; Ke Lin
As a fundamental fluid-structure interaction (FSI) phenomenon, vortex-induced vibrations (VIVs) of circular cylinders have been the center of the FSI research in the past several decades. Apart from its scientific significance in rich physics, VIVs are paid great attentions by offshore engineers, as they are encountered in many ocean engineering applications. Recently, with the development of research
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