[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

This paper assesses some recent trends in the novel numerical meshless method smoothed particle hydrodynamics, with particular focus on its potential use in modelling free-surface flows. Due to its Lagrangian nature, smoothed particle hydrodynamics (SPH) appears to be effective in solving diverse fluid-dynamic problems with highly nonlinear deformation such as wave breaking and impact, multi-phase mixing processes, jet impact, sloshing, flooding and tsunami inundation, and fluid–structure interactions. The paper considers the key areas of rapid progress and development, including the numerical formulations, SPH operators, remedies to problems within the classical formulations, novel methodologies to improve the stability and robustness of the method, boundary conditions, multi-fluid approaches, particle adaptivity, and hardware acceleration. The key ongoing challenges in SPH that must be addressed by academic research and industrial users are identified and discussed. Finally, a roadmap is propose...

Smoothed particle hydrodynamics (SPH) for free-surface flows: past, present and future

Smoothed particle hydrodynamics method for fluid flows, towards industrial applications: Motivations, current state, and challenges

Comparative study on accuracy and conservation properties of two particle regularization schemes and proposal of an optimized particle shifting scheme in ISPH context

The article aims at providing an up-to-date review on several latest advancements related to particle methods with applications in coastal and ocean engineering. The latest advancements corresponding to accuracy, stability, conservation properties, multiphase multi-physics multi-scale simulations, fluid-structure interactions, exclusive coastal/ocean engineering applications and computational efficiency are reviewed. The future perspectives for further enhancement of applicability and reliability of particle methods for coastal/ocean engineering applications are also highlighted.

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On the state-of-the-art of particle methods for coastal and ocean engineering

Study on the ditching of space capsules using the smoothed particle hydrodynamics method

The nanotrench structure can obviously enhance the stability of bulk nanobubbles and control the formation and positions of surface nanobubbles. The hydrophilic deformed graphene domains prevent interaction between two neighboring surface nanobubbles.

Effects of nanostructured substrates on the dynamic behavior of nanobubbles

Particle propulsion by an attached acoustic cavitation bubble under strong ultrasonic wave excitation occupies the core of many applications, including ultrasonic cleaning, ultrasonography, targeted therapy, and microbubble motors. However, the driving capacity and mode of bubbles in the field of ultrasonics are far from being well understood, which severely limits its applicability in a variety of fields. In this study, a fluid-structure interaction model based on the boundary integral method (BIM) is proposed to simulate complex interactions between a suspended spherical particle and an attached cavitation bubble. A one-to-one comparison between the numerical results and experimental data demonstrates the distinct advantage of our model over conventional approaches. Thereafter, we systematically investigate the dependence of bubble-particle interactions on the governing parameters, including the amplitude and phase of the ultrasonic wave, particle density, and particle-to-bubble size ratio. We also document different types of bubble dynamic behaviors under various governing parameters. Finally, we obtain scaling laws for the maximum displacement of the particle with respect to the governing parameters.

Particle propulsion from attached acoustic cavitation bubble under strong ultrasonic wave excitation

Abstract The essence of sub-critical transition of oscillatory boundary-layer flows is the non-modal growth of finite-amplitude disturbances. The current understanding of the mechanisms of the orderly and bypass transitions of oscillatory boundary-layer flows is limited. The present study adopts optimisation approaches to predict the maximum energy amplification of two- and three-dimensional perturbations in response to the optimal initial disturbance with or without external forcing. A series of direct numerical simulations are also performed to compare with the results obtained from the stability analyses. In particular, the optimal initial perturbation similar to a Tollmien–Schlichting (T–S) wave yields the largest transient growth under the combined effects of the Orr mechanism and inflectional point instability. With a considerable level of two-dimensional disturbance, the vortex tube nonlinearly develops from the T–S-like wave, and then either deforms into a $\varLambda$-vortex in the near-wall region or rolls up to the free shear region. The further burst of turbulence can follow the first pathway as K-type transition or the second one as vortex tube breakdown due to the elliptical instability. Additionally, non-modal growth can initiate the inception of streaky structures by favourable three-dimensional initial perturbations and/or forcing. The secondary instabilities responsible for the streak breakdown are classified as the varicose (symmetric) and sinuous (anti-symmetric) modes. Under a sufficiently high level of three-dimensional disturbance, the bypass transition is predominantly characterised by the formation of the sinuous mode and turbulent spots, which leads to the suppression of inflection point instability.

A-Man Zhang

Papers

Study on the ditching of space capsules using the smoothed particle hydrodynamics method

Effects of nanostructured substrates on the dynamic behavior of nanobubbles

Particle propulsion from attached acoustic cavitation bubble under strong ultrasonic wave excitation

Non-modal growth of finite-amplitude disturbances in oscillatory boundary layer

A coupling approach of the isogeometric–meshfree method and peridynamics for static and dynamic crack propagation