Numerical Study of Unsteady Behavior of Cloud Cavitation by Smoothed Particle Hydrodynamics

2021 ◽  
Author(s):  
Takahiro Ushioku ◽  
Hiroaki Yoshimura
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Numerical Study ◽  
Cloud Cavitation ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Unsteady Behavior

Numerical Study of Unsteady Behavior of Cloud Cavitation by Smoothed Particle Hydrodynamics

2020 ◽  
Author(s):  
Takahiro Ushioku ◽  
Hiroaki Yoshimura
Keyword(s):  
Numerical Analysis ◽  
Multiphase Flow ◽  
Smoothed Particle Hydrodynamics ◽  
Collective Motion ◽  
Numerical Study ◽  
Water Jet ◽  
Lagrangian Description ◽  
Cloud Cavitation ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

Abstract Cavitation generates a portion of cavities called a cavitation cloud, which performs a collective unsteady motion of repeating the process of growth and collapse. In particular, it is considered that a high-pressure shock wave propagates associated with the collapse. In order to understand such unsteady behaviors of the cavitation cloud, much effort has been made for the numerical analysis of internal flows of the cavitation cloud. However, it is not clear how such a cavitation cloud can be identified as a physical entity nor how its unsteady collective motion can be elucidated in the context of the multiphase fluid flow. In this study, we make a two-dimensional numerical analysis of the multiphase flow of the submerged bubbly water jet injecting into still water through a nozzle. To model the bubbly water jet, we employ the mixture model of liquids and gases, and we utilize the Smoothed Particle Hydrodynamics method for the numerical analysis of the unsteady flows in Lagrangian description. Finally, in order to clarify the unsteady behaviors of the cloud cavitation, we show how the cavitation cloud can be generated in the context of velocity fields in the multiphase flow and in particular, we clarify how twin vortices induced by the water jet play an essential role in the expansion and shrinkage of the cloud.

scholarly journals A Numerical Study of Fluid Flow in a Vertical Slot Fishway with the Smoothed Particle Hydrodynamics Method

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1928 ◽  
Author(s):  
Gorazd Novak ◽  
Angelantonio Tafuni ◽  
José M. Domínguez ◽  
Matjaž Četina ◽  
Dušan Žagar
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Numerical Study ◽  
Free Surface Flows ◽  
Open Boundary ◽  
Doppler Velocity ◽  
Vertical Slot ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
Vertical Slot Fishway

Fishways have a great ecological importance as they help mitigate the interruptions of fish migration routes. In the present work, the novel DualSPHysics v4.4 solver, based on the smoothed particle hydrodynamics method (SPH), has been applied to perform three-dimensional (3-D) simulations of water flow in a vertical slot fishway (VSF). The model has been successfully calibrated against published field data of flow velocities that were measured with acoustic Doppler velocity probes. A state-of-the-art algorithm for the treatment of open boundary conditions using buffer layers has been applied to accurately reproduce discharges, water elevations, and average velocity profiles (longitudinal and transverse velocities) within the observed pool of the VSF. Results herein indicate that DualSPHysics can be an accurate tool for modeling turbulent subcritical free surface flows similar to those that occur in VSF. A novel relation between the number of fluid particles and the artificial viscosity coefficient has been formulated with a simple logarithmic fit.

scholarly journals Numerical study of rainstorm influence on parachute airdropping based on the smoothed particle hydrodynamics/arbitrary Lagrangian–Eulerian coupling method

2020 ◽  
Vol 15 ◽  
pp. 155892502091561
Author(s):  
Linbo Yan ◽  
Zhengkai Sun ◽  
Han Cheng
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Wind Field ◽  
Numerical Study ◽  
Great Influence ◽  
Coupling Method ◽  
Influential Factor ◽  
Arbitrary Lagrangian Eulerian ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
And Performance

In order to study the influence of rainstorm on parachute dropping, the smoothed particle hydrodynamics/arbitrary Lagrangian–Eulerian coupling method is proposed. Finite elements are used to describe the continuous material such as fabric and air flow field, and the smoothed particle hydrodynamics particles are used to describe the discrete raindrops. The coupling between different fluid and structure is realized by penalty function. In order to distinguish the most influential factor of rainstorm environment on parachute, the effects of raindrop field and wind field in rainstorm are studied, respectively. It could be found that the raindrop fields with different droplet sizes have little effect on the parachute’s shape, opening shock, and performance according to the comparative analysis, while the vertical wind field has a great influence on parachute’s deceleration performance. The wind field, not the raindrop field, is the most important factor affecting the parachute’s deceleration performance. The method and conclusions in this article could provide some references for parachute design.

A Numerical Study on the Pull-Out Strengths of Anchor Bolts Embedded in Concrete Using the Smoothed Particle Hydrodynamics Method

2016 ◽  
Vol 711 ◽  
pp. 1111-1117 ◽  
Author(s):  
Yoshimi Sonoda
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Failure Modes ◽  
Numerical Study ◽  
Failure Process ◽  
Embedment Depth ◽  
Anchor Bolt ◽  
Pull Out ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Anchor Bolts

The strength of an anchor bolt in concrete structure under pull-out load is usually designed by three possible failure modes such as fracture of anchor bolt, cone failure of concrete and bond failure between anchor bolt and concrete. In general, the design load is considered the smallest load corresponding to the aforementioned failure mechanisms. However, unexpected failure often occurs in the anchorage zone due to the complex failure or the change of failure condition. Therefore, it is important to develop the accurate analysis method of ultimate load bearing capacity of the anchor bolt. In this study, we conducted an analytical study using Adaptive Smoothed Particle Hydrodynamics (ASPH) in order to simulate the failure process of anchorage zone and discussed the effect of embedment depth of anchor bolts on their ultimate strength.

scholarly journals Modelling aerated flows with smoothed particle hydrodynamics

2015 ◽  
Vol 17 (4) ◽  
pp. 493-504 ◽  
Author(s):  
Michael Meister ◽  
Wolfgang Rauch
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Bubble Column ◽  
Numerical Study ◽  
Air Entrainment ◽  
Future Perspective ◽  
Engineering Practice ◽  
Special Focus ◽  
Practical Applications ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

Modelling aerated flows is a complex application of computational fluid dynamics (CFD) since the interfaces between air and water change rapidly. In this work, the simulation of aerated flows with the smoothed particle hydrodynamics (SPH) method is investigated with a focus towards the application in engineering practice. To prove the accuracy of the method, the processes of air entrainment and rising air bubbles are studied. Through monitoring the evolution of the bubble contours it is shown that the novel approach of adding artificial repulsion forces at the interface does not alter the dynamics but stabilizes the flow. Building on these fundamental processes we extend the discussion to practical applications with a special focus on forced aeration. Since the employment of a detailed SPH model to practical problems remains out of bounds due to the high computational demand, we propose a combined experimental and numerical study where experimental bubble characteristics are imposed on the numerical simulation. Based on the data of the conducted bubble column experiment, the computational demand is significantly decreased such that the oxygen consumption due to biokinetic processes can be modelled. The future perspective is to apply SPH to urban water systems, e.g., for simulating detailed processes in wastewater treatment and sewer hydraulics.

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