Smoothed-particle hydrodynamics simulation

Simulations of this scenario have been performed by Lee (Lee 2001 and references therein) using Newtonian gravity and polytropic equations of state of varying stiffness. Ruffert, Janka and Eberl performed similar simulations but with a detailed microphysics input (nuclear equation of state and neutrino leakage ). In our own simulations of NS-BH mergers we used a relativistic mean field equation of state together with three-dimensional smoothed particle hydrodynamics and a detailed, multiflavour neutrino treatment. 

In 1977, Lucy [1] and Gingold and Monaghan [2] independently introduced the so-called smoothed particle hydrodynamics method which is one of the oldest meshless methods. The method was originally developed for astrophysi-cal studies such as formation of asteroids and the evolution of galaxies and has now become a standard tool in this field. In recent years, SPH has been extensively used for various fluid flow problems including both compressible and incompressible flow regimes. The method has been recently used for simulation of the generalized non-Newtonian and viscoelastic fluid flow problems. The SPH method has been also... 

FIGURE 26.24 The snapshots from a simulation using smoothed particle hydrodynamics of the Rayleigh-Taylor instahihty for gases. The size of the hox is approximately 1 cm. The dark grey system represents fluid which is 10 times heavier than the lighter one placed in the bottom (invisihle in this figure). Approximately 10 SPH particles have been modeled. 

Lin B, Jin X, Zheng R, Costa FS, Fan Z (2004) 3D fiber orientation simulation for plastic injection molding. NUMIFORM 2004. AIP Conference Proceedings,vol 712, pp 282-287 Lipscomb DD II, Denn MM, Hur DU, Boger DV (1988) The flow of fiber suspension in complex geometry. J Non-Newtonian Fluid Mech 26 297-325 Liu GR, Liu MB (2003) Smoothed particle hydrodynamics, a meshfree particle method. World Scientific, Singapore... 

Particle-based simulation techniques include atomistic MD and coarse-grained molecular dynamics (CG-MD). Accelerated dynamics methods, such as hyperdynamics and replica exchange molecular dynamics (REMD), are very promising for circumventing the timescale problem characteristic of atomistic simulations. Structure and dynamics at the mesoscale level can be described within the framework of coarse-grained particle-based models using such methods as stochastic dynamics (SD), dissipative particle dynamics (DPD), smoothed-particle hydrodynamics (SPH), lattice molecular dynamics (LMD), lattice Boltzmann method (IBM), multiparticle collision dynamics (MPCD), and event-driven molecular dynamics (EDMD), also referred to as collision-driven molecular dynamics or discrete molecular dynamics (DMD). 

Tartakovsky, A.M., Meakin, E, Scheibe, T.D. Eichler West, R.M. Simulations of reactive transport and precipitation with smoothed particle hydrodynamics. J. Comput. Phys. 222 (2007), pp. 654-672. 

Abstract A numerical model is constructed for the viscoelastic phase separation in polymer solutions based upon the two-fluid model using the method of the smoothed-particle hydrodynamics. Computer simulations are carried out with this model in two dimensions and efiects of the stress relaxation time on morphology of domains are examined. It is observed that the more... 

Recently, a new type of phase separation called viscoelastic phase separation was observed in polymer solutions or dynamically asymmetric fluid mixtures [1-3]. It is an interesting feature of this phenomenon that network-like domains of more viscous phase emerge in a transient regime. It has little been understood what ingredient of physics is crucial to this phenomenon. Various numerical approaches have been made for the phase separation phenomena in binary fluid systems in the last decade [4-6]. Most of these studies have been concerned with classical fluids and have not involved viscoelasticity. A new numerical model was recently proposed by the author [7] based upon the two-fluid model [8,9] using the method of smoothed-particle hydrodynamics (SPH) [10,11]. In this model the Lagrangian picture for fluid is adopted and the viscoelastic effect can easily be incorporated. In this paper we carry out a computer simulation for the viscoelastic phase separation in polymer solutions with this model. 

At the intermediate wavelengths no useful analytic forms of solution are known. On the other hand, (138) yields readily to numerical solutions. Such results show a smooth interpolation between characteristic hydrodynamic and free-particle behavior. Notice, however, that in this region it is essential to treat the collisions and molecular flow on equal footing for this reason it would be inappropriate to apply either (154) or (155). Since the intermediate k range is particularly relevant to neutron inelastic scattering studies of liquids and related computer molecular dynamics simulations, the validity of our kinetic model solutions is of interest. 

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