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Abstract In this paper, we develop an optimal particle setup method for initial condition with Centroidal Voronoi Particle (CVP) dynamics, which combines the Centroidal Voronoi Tessellation (CVT) and Voronoi Particle (VP) concept. CVT optimizes the energy function in terms of compactness and consequently ensures the isotropy of particle distribution. The CVT configuration is computed by Lloyd's algorithm, which decreases the energy function monotonically. A physics-motivated model equation with tailored equation of state (EOS) is employed to relax the Voronoi particle system such that the convergent equilibrium matches the target configuration. The resulting particle distribution approximates the given analytical profiles of spatially adaptive density, smoothing-length and mass distribution with high interpolation accuracy. The level-set method is introduced to describe arbitrarily complex geometries. A set of Smoothed Particle Hydrodynamics (SPH) simulations is computed to demonstrate the performances of the proposed method. Without parameter tuning, good performance is obtained for presented benchmarks implying its promising potential. [ABSTRACT FROM AUTHOR]

Accurate mesh-free simulation of fluid flows involving complex boundaries requires that the boundaries be captured accurately in terms of particles. In the context of incompressible/weakly-compressible fluid flow, the SPH method is more accurate when the particle distribution is uniform. Hence, for time-accurate simulation of flow in the presence of complex boundaries one must have both an accurate boundary discretization and a uniform distribution of particles to initialize the simulation. This process of obtaining an initial uniform distribution of particles is called "particle packing". In this paper, we compare and implement various particle packing algorithms present in the literature. We propose an improved SPH-based algorithm which produces uniform particle distributions of both the fluid and solid domains in two and three dimensions. We demonstrate the accuracy of the new algorithm by constructing some challenging geometries. The implementation of the algorithm is open source, and the manuscript is fully reproducible. Program title: SPHGeom CPC Library link to program files: https://doi.org/10.17632/hz7pg3rhdb.1 Code Ocean capsule: https://codeocean.com/capsule/5490642 Licensing provisions: BSD 3-Clause Programming language: Python External routines/libraries: PySPH (https://github.com/pypr/pysph), matplotlib (https://pypi.org/project/matplotlib/), automan (https://pypi.org/project/automan/), ParaView(https://www.paraview.org/download/). Nature of problem: Particle methods require that complex geometry be accurately represented when discretized with particles. The particles should be uniformly distributed inside, outside, and on the surface of the geometry. This can be achieved using the proposed particle packing algorithm. For a fluid flow past a solid body, the code generates a set of solid particles inside and on the surface surrounded by fluid particles such that the density is approximately constant. These particles can be placed in a larger simulation. Solution method: : The proposed algorithm uses a number density gradient, a repulsion force, and a damping force to move particles. Particles are constrained near the boundary to move along the surface. Particles are iteratively projected onto the boundary surface. Once a desired distribution of particles is achieved, the particles are separated into interior and exterior particles using the boundary information. This may be used directly as an input for particle-based simulation. Additional comments: : The source code for this repository can be found at https://gitlab.com/pypr/sph_geom. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new contact algorithm to analyze an elasto-plastic contact problem using the SPH (Smoothed Particle Hydrodynamics) method. This algorithm is available to both contact types, which are the particle-to-particle contact and the surface-to-particle one. It is employed to determine the actual boundary normal vector and apply the reproducing condition in the cylindrical coordinate. The variational equation based on the virtual work principle is derived and its solution is obtained by the penalty method, which includes both a penetration and a penetration rate. Numerical simulations are presented to show that the proposed algorithm can be applied to the elasto-plastic contact problem for the case that either both bodies are deformable or one is a rigid wall and the other is deformable. Two colliding bodies can be separated with the expected rebound velocity and the total contact force acting on between them similar to theoretical value. Results of the rod impact analysis are shown to be in agreement with the ones obtained by other solution and experiment. [Copyright &y& Elsevier]