Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> A. HIGH SPEED COLLISION AND BLASTING <s> The application of the Smoothed Particle Hydrodynamics method to the fragmentation of rotating cloud and disk systems is described, allowing for molecular cooling due to H2 and CO. A novel approach to solving Poisson's equation for disklike structures which exploits the multigrid algorithm is also described. Numerical studies are presented which investigate the evolution of both rotating clouds and Maclaurin disks, in each case with both an isothermal equation of state and with molecular cooling. The results establish the influence of molecular cooling on the fragmentation of molecular clouds. The isothermal sequences, if they fragment at all, do so into far fewer lumps than the cooling sequences. This is not due to a cooling instability as such, but rather to the reduced thermal support. One of the sequences shows a remarkable similarity to the W49A star-forming region. 27 refs. <s> BIB001 </s> Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> A. HIGH SPEED COLLISION AND BLASTING <s> For 3D flow visualization a variety of techniques can be used, such as drawing particle trajectories, vector plots, contouring, and particle tracing, each with its own advantages. A new technique is presented that is a combination of particle tracing and shaded surface rendering, capturing the advantages of both: surface interpretation and a moving texture of particles. The technique is based on the use of so-called surface-particles. A surface-particle is a very small flat part of a surface, modelled as a point with a surface normal. The combined use of many surface-particles can lead to surfaces. Various types of visualization methods (lines, tubes, surfaces, and objects) can be realized by variation of the properties of the particle source. Their applications in 3D flow visualization are described. <s> BIB002 </s> Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> A. HIGH SPEED COLLISION AND BLASTING <s> SPH (Smoothed Particle Hydrodynamics) is a gridless Lagrangian technique which is appealing as a possible alternative to numerical techniques currently used to analyze high deformation impulsive loading events. In the present study, the SPH algorithm has been subjected to detailed testing and analysis to determine the feasibility of using PRONTO/SPH for the analysis of various types of underwater explosion problems involving fluid-structure and shock-structure interactions. Of particular interest are effects of bubble formation and collapse and the permanent deformation of thin walled structures due to these loadings. These are exceptionally difficult problems to model. Past attempts with various types of codes have not been satisfactory. Coupling SPH into the finite element code PRONTO represents a new approach to the problem. Results show that the method is well-suited for transmission of loads from underwater explosions to nearby structures, but the calculation of late time effects due to acceleration of gravity and bubble buoyancy will require additional development, and possibly coupling with implicit or incompressible methods. <s> BIB003 </s> Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> A. HIGH SPEED COLLISION AND BLASTING <s> This paper presents a study of micro channel flows using a meshfree particle approach. The approach is based on smoothed particle hydrodynamics (SPH) and its variant, adaptive smoothed particle hydrodynamics (ASPH). The incompressible flow in the micro channels is modeled as an artificially compressible flow. The surface tension is incorporated into the equations of motion. The classic Poiseuille flow and a practical micro channel flow problem of flip-chip underfill encapsulation process are investigated. It is found that the adaptive kernel can well match the computational geometry with long channels and can greatly save computational time. The simulation results are in close agreement with the analytical solutions. <s> BIB004 </s> Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> A. HIGH SPEED COLLISION AND BLASTING <s> Underwater explosion,involving gas-liquid two-phase flows,is a problem of dynamic boundary.Numerical simulation of underwater explosion problems is a challenge for traditional mesh-based numerical methods due to the inherent feature such as moving interface.As a Lagrangian method,SPH can track the moving interface between the gas produced by the explosion and the surrounding water effectively.In this paper,we apply SPH to simulate the process of underwater explosion.Some important improvements are made in our SPH code to suit for the needs of simulating underwater explosion especially in optimizing the smoothing length.The results obtained from SPH show that the present method can successfully simulate large deformation or strong non-linear problem such as underwater explosion at high accuracy with less computational effort,and numerical stability as well. <s> BIB005 </s> Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> A. HIGH SPEED COLLISION AND BLASTING <s> A simple treatment for surface tension in immiscible fluids is proposed for macro-scale particle methods such as smoothed particle hydrodynamics (SPH) and macro-scale pseudo-particle modeling (MaPPM). By introducing a repulsion between the neighboring particles of different fluids, surface tension arises automatically, while simple equations of state are still possible for each phase. This treatment is validated by comparative simulations on the deformation of a square liquid drop in suspension using the volume of fluid (VOF) method. The relationship between surface tension and the repulsion intensity parameter in our model is obtained by the sessile drop method. <s> BIB006 </s> Survey on Smoothed Particle Hydrodynamics and the Particle Systems <s> A. HIGH SPEED COLLISION AND BLASTING <s> An implementation of the smoothed particle hydrodynamic (SPH) method is adopted to investigate underwater explosion near air-water surface. The interaction between the water and the air during the process of explosion is investigated. The SPH method, as a kind of meshfree, provides a very attractive approach in dealing with large deformations and multi-material interactions. A two-dimensional SPH code is developed to simulate the complex physical phenomenon of underwater explosion near air-water surface. The distributions of the density and the pressure have also been qualitatively analyzed, and some interesting results have been obtained. Finally, the results show that the SPH method can represent the physical process of underwater explosion near air-water surface. The ability of SPH method in simulating compressible multi-fluid flows has also been certified. <s> BIB007
The original application of SPH is in astrophysical phenomena BIB001 because celestial motion can also be modeled by simulating a compressible fluid. SPH was introduced to a vast range of problems in both fluid and solid mechanics for a strong capability to incorporate complex physics into the SPH formulations  , including high explosive detonation and explosion BIB003 -  , microfluidics or micro drop dynamics BIB004 - BIB006 , heat conduction  , fluid-solid interaction BIB002 , and metal forming  . Given that the SPH method has the advantages of the Lagrangian and meshless methods, it is very suitable for simulating complex deformation problems such as an explosion. Zong et al. BIB005 studied the SPH method of simulating two-dimensional fluid underwater explosion. Xiubo studied the detonation simulation using SPH and compared it with the earlier method. Yang et al. BIB007 applied SPH to simulate the near-surface explosion and reproduce the interaction process of detonation products, water, and air. The current SPH method of the study of the explosion remains only in a relatively simple situation because additional complex surface chemical phenomena cannot be simulated. Furthermore, in the case of water media simulation, the explosive gas particles easily penetrate the water medium, showing a need for effective interface treatment.