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Violent Wave Impacts and Loadings using the δ-SPH Method
Published in David M Kelly, Aggelos Dimakopoulos, Pablo Higuera, Advanced Numerical Modelling of Wave Structure Interactions, 2021
Matteo Antuono, Salvatore Marrone, Andrea Colagrossi
In the SPH literature several techniques have been proposed to impose the correct boundary conditions along solid profiles. Early techniques relied on repulsive (Monaghan, 1989) or dynamic particles ( Dalrymple and Knio, 2001). Later on ghost fluid approaches ( Randles and Libersky, 1996; Colagrossi and Landrini, 2003) were proposed and adapted for general body shapes as in the case of the fixed ghost particles Marrone et al., 2011 or dummy particles Adami et al., 2012. More recently semi-analytical ( Kulasegaram et al., 2004; Leroy et al., 2014) approaches and methods based on the evaluation of the flux normal to the wall (Marongiu et al., 2012; De Leffe et al., 2009) have been proposed. Due to its flexibility, robustness and accuracy, the fixed ghost particle method is one of the best suited technique for the applications considered in the present Chapter. For this reason, we just restrict the discussion to such a method and address the interested readers to the above mentioned works for alternative approaches.
Numerical study of combined wave overtopping and storm surge overflow of strengthened levee
Published in Lin Li, Farshad Amini, Yi Pan, Saiyu Yuan, Bora Cetin, Hydraulics of Levee Overtopping, 2020
Lin Li, Farshad Amini, Yi Pan, Saiyu Yuan, Bora Cetin
SPH is a meshless fully Lagrangian method for obtaining numerical solutions for the equations of fluid dynamics by replacing the fluid with a set of particles (e.g., Monaghan 2005). In this approach, the particles are interpolation points from which fluid properties can be calculated. The SPH particles are also material particles which can be treated like any other particle system. The advantages of SPH include (1) no meshor grid is required, and SPH can deal with large deformations of the free surface and interface problems; (2) no mesh refinement for any change in density, viscosity, and flow morphology is needed; (3) no gap between the continuum and fragmentation for brittle fracture and subsequent fragmentation in damaged solids exists; and (4) computational advantage (e.g.; Monaghan 2006; Li et al. 2012; Rao et al. 2012; Li et al. 2013, 2015a). The computational advantage feature of the SPH is very useful for two-phase flow with water–structure interactions.
Three-Dimensional (3D) Numerical Modeling of Morphogenesis in Dehydrated Fruits and Vegetables
Published in Guangnan Chen, Advances in Agricultural Machinery and Technologies, 2018
C. M. Rathnayaka, H. C. P. Karunasena, Wiji Senadeera, Lisa Guan, Y. T. Gu
Compared to conventional grid-based approaches, SPH has been proven to perform well in advanced modeling applications, such as large deformations related to multiphase flows, free surfaces, deformable boundaries, and moving interfaces (Liu and Liu, 2010; Morris, Fox, and Zhu, 1997). For instance, when simulating explosions, large deformations exist, and the system is essentially composed of discretized domain segments moving relative to each other, which has been successfully modeled with SPH (Zhang, 1976; Liu and Liu, 2010). Likewise, high velocity impact (HVI) systems and subsequent shock wave propagation problems (Zukas, 1990) with discontinuities and phase fragmentations can effectively and efficiently be simulated with SPH (Liu and Liu, 2003b; Frank and Perré, 2010). The material boundaries, moving boundaries, and free surface flows could be tracked in SPH simulations, even in complicated systems whereas for grid-based methods such tasks would be comparatively difficult. The versatility of SPH could allow one to couple SPH and Molecular Dynamics (MD) or SPH and Dissipative Particle Dynamics (DPD) for examining multiscale problems in biomechanics.
Understanding laser-metal interaction in selective laser melting additive manufacturing through numerical modelling and simulation: a review
Published in Virtual and Physical Prototyping, 2022
Abdelkrim Bouabbou, Sebastien Vaudreuil
Particle simulation is a rapidly evolving interdisciplinary research field where understanding interactions between particles and their effects from the micro- to the macroscale is the main objective. The mesoscale in AM-SLM refers to a modelling based on the actual particle morphology, directly calculating the heating and melting effects of the laser on metal particles. It then describes the complex flow behaviour of liquid metal between particles, the scale of which is in micrometres. Furthermore, it includes thermodynamics and hydrodynamics effects such as wetting, capillarity, and evaporation. These phenomena are studied mainly by using DEM for powder bed generation coupled with a mesh-based method to solve the thermo-mechanical dynamics of the melt pool. Smooth particle hydrodynamics (SPH) however is a method used for simulating particles in motion that addresses physical problems that other mesh-based methods cannot solve.
Experimental and numerical investigation of hyper-elastic submerged structures strengthened with cable under seismic excitations
Published in European Journal of Environmental and Civil Engineering, 2020
When the fluid is assumed to be incompressible, Poisson’s equations should be solved resulting the higher computational time (incompressible SPH – ISPH). To avoid solving Poisson’s equations, weakly compressible SPH model is used. According to the weakly compressible SPH assumption, the pressure of a particle is calculated by: where is the initial density. In order to satisfy weakly compressible assumption, density variations are kept below 1%. Therefore, speed of sound should be used much lower than that of the real fluid. According to Morris et al. (1997), the square of the speed of sound should be compatible with the following equation: where is the magnitude of external force, is the length scale, is the fluid bulk velocity, is the absolute density variation. In order to ensure the neighbouring particles to move with closer velocities, the XSPH correction can be used (Monaghan, 1994).
Modelling strategies for numerical simulation of aircraft ditching
Published in International Journal of Crashworthiness, 2018
The use of a mesh-free formulation is an additional alternative to the traditional FE methods for representing fluid domains in FSI applications. The smoothed particle hydrodynamics (SPH) method [20,32] is a particular mesh-free formulation available in LS-DYNA. It is based on the application of an interpolation scheme, which makes use of smoothing kernel functions with a compact support, in order to obtain the governing equations of a discrete system of elements. The particle nature of the SPH formulation makes it suitable for simulations that involve arbitrary large displacements of the material. Therefore, it can be adopted for modelling the fluid domain in FSI simulations, while traditional Lagrangian FEs are used to represents the structural part of the model. The accuracy of the SPH formulation is related to the distribution of the discrete particles relative to each other: in the optimal case a uniform discretisation, where each SPH element is surrounded by the same number of particles, is preferable and particular attention is required to apply local refinement. However, a fine discretisation is required in the region of the FSI in order to capture the small scale hydrodynamics phenomena, while a coarser distribution of the particles would be preferable elsewhere in order to reduce the computational time.