Many theoretical and nurnerical atternpts have been made to understand the late-stage dynalnicsof phase separations in off-critically quenched bi nary systelTIS However, in spite its irnportance, an effect of encoun ters alnong droplets has been neglected ia previous works, for a nomenological theory Davies

Thrombogenesis is said to play an important role in the rupture of cerebral artery aneurysms and it was reported that the degree of platelet aggregation in an aneurysm had a significant correlation with the flow pattern in the aneurysmal dome.In this study, flows in three different models of cerebral saccular aneurysms at artery bifurcations were numerically investigated to compare flow patterns from a viewpoint of likelihood of platelet aggregation.It was shown that the relative size of the aneurysmal dome had a greater influence on the formation of a low-speed region responsible for active platelet aggregation than geometric features such as the aspect ratio of the aneurysm and the angle of the bifurcation.

Magnetic fluid is a compound material of colloidal liquid, consisting of a base suspension liquid, nano sized magnetic particles such as Co-ferrite or Ba-ferrite which have their own magnetic moment, and surfactant.In order to calculate the microstructure formation process of magnetic fluid, we use the Langevin-type microscopic equation of motion and perform the molecular dynamics simulation. In the study, we investigate physical force originated by the magnetic and surrounding fluid flow and torque.We consider the rotating field effect, and obtain layering structures in various ranges of the rotating frequency and packing density. These structures are found in ER and MR fluid, however, not yet found in MF.

Brownian dynamics simulations of interacting magnetic particles in a quasi-two-dimensional ferrofluid system are performed at zero temperature, under the influence of oscillatory shear flow in the absence of external magnetic fields. Starting from chain-like clusters of the particles, we study the time-dependent behavior of both magnetization and microstructures of the ferrofluid by changing values of two parameters, the shear rate strength and frequency of oscillatory shear flow. Simulation results show that there are three different dynamical regimes for the chain clusters dynamics, depending on these two parameters. Scaling behavior of the asymptotic magnetization is also observed for a certain range of parameters.

We simulate the current-driven vortex motion in a two-dimensional square sample of type-II superconductors, by using a logarithmically interacting point vortex model involving effect of temperature, transport current, random pinning centers, magnetic field, and Magnus force. We also take into account both the vortex pair nucleation and the vortex pair annihilation processes in the model. Simulation results show that the negative Hall effect is observed for a certain range of the model parameters. Such an anomalous behavior is thought to originate from freely moving antivortices with the long life-time due to the collective dynamics of this vortex system on the background of weakly pinned vortex lattice.

We study the radial current driven vortex dynamics in the Corbino disk sample at zero field, by using a logarithmically interacting point vortex model involving effect of temperature, random pinning centers, and disk wall confinement force. We also take into account both the current induced vortex pair nucleation and the vortex pair annihilation processes in the model. Simulation results demonstrate that the vortex motion induced voltage exhibits almost periodic pulse behavior in time, observed experimentally, for a certain range of the model parameters. Such an anomalous behavior is thought to originate from large fluctuations of the vortex number due to the collective dynamics of this vortex system.

We study the radial current driven vortex dynamics in the Corbino disk sample at zero field, by using a logarithmically interacting point vortex model involving effect of temperature, random pinning centers, and disk wall confinement force. We also take into account both the current induced vortex pair nucleation and the vortex pair annihilation processes in the model. Simulation results demonstrate that the vortex motion induced voltage exhibits almost periodic pulse behavior in time, observed experimentally, for a certain range of the model parameters. Such an anomalous behavior is thought to originate from large fluctuations of the vortex number due to the collective dynamics of this vortex system.

Thrombi are often found in aneurysms and are considered to play an important role in rupture. It is crucial to scrutinise any correlation between the probability of rupture and the extent to which thrombi are generated in the aneurysm. Numerical techniques such as computational fluid dynamics (CFD) are promising tools in the biomedical field. However, there are, at present, no models that allow us to evaluate thrombus generation. The authors aim at the proposal of such a model. In the present study, the process of platelet aggregation is considered. In blood flow near the entry to an aneurysm, red blood cells are haemolysed due to high shear stress or high pressure. The ensuing release of adenosine diphosphate (ADP) induces the aggregation. Making reference to actual aggregation curves of human plasma for various ADP concentrations, the authors have modelled the rate at which the density of aggregated platelets continues to increase in the aggregation process. A combination of CFD and the present model enables us to obtain the distribution of platelets clotting in an aneurysm.

To study the shear rigidity of vortex systems, we simulate the radial current driven vortex dynamics in the two-dimensional Corbino disk geometry of type-II superconductors. The radial currents in the disk induce the spatially inhomogeneous Lorentz force, yielding the local shear stress to the vortex lattice. Molecular dynamics simulations of a point vortex model demonstrate that (1) at low currents the vortices rotate as a rigid solid, (2) at large currents the vortices move freely as a liquid, (3) at intermediate currents the complicated plastic slippage of neighboring annular section of the vortex array occurs, and (4) temperature effects enhance the plastic slippage events.

We numerically study the possible formation of ordered structures in block copolymer systems by introducing mobile particles in a periodically driving field. The particles which have a preferential attraction to one of two monomers in the diblock, significantly perturb the mesoscopic phase separation of the system. We examine the dependence of formed morphology on the oscillating fields, and discuss how to realize stable and highly ordered structures.

We present two‐dimensional computer simulation results of magnetic vortex systems driven by Lorentz force in type‐II superconductors having the Corbino disk geometry. Langevin dynamics simulations of a point vortex model demonstrate that (1) at low injected currents in the superconductor the vortices rotate as a rigid solid having the linear velocity profile as a function of r with r the distance from the disk center, (2) at large currents the vortices move free as a liquid having the inversely linear velocity profile, and (3) at moderate currents the complicated plastic flow of the vortices appears.

Magnetic fluid is a compound material of colloidal liquid, consisting of a base suspension liquid, nano sized magnetic particles such as Co-ferrite or Ba-ferrite which have their own magnetic moment, and surfactant. In order to calculate the microstructure formation process of magnetic fluid, we used the Langevin-type microscopic equation of motion and perform the Molecular Dinamics simulation. In the study, we consider physical force originated by the magnetic and surrounding fluid flow and torque. We were able to show the various microscopic patterns of formation process in oscillatory shear flow.

We performed simulations of the vortex dynamics in the 2D system with a periodic pinning array to investigate the origin of narrow-band noise (NBN) in type-II superconducting films. The simulations show that the periodic pinning potential generated NBN and the first peak frequency of NBN was proportional to the voltage. Furthermore, it is shown that the initial vortex arrangement affected the first peak frequency.

The purpose of this study is to clarify the state of the heat loss in a direct-injection diesel engine. Originally developed thin-film thermocouples (TFTs) are embedded into the combustion chamber walls for accurate measurement of instantaneous surface temperature from which instantaneous heat flux is evaluated through the heat conduction equation. Measured points are arrayed on the cavity bottom, the cavity side wall, the piston top, and the cylinder head. The TFTs are designed and fabricated so that disturbance of the temperature field is minimized when they are embedded into the combustion chamber walls. As a result, it is observed that the behaviour of instantaneous temperature and heat flux depends on the radius of the measured point. Measured points located radially inwards seem to be influenced by the combustion flame considerably more than those located outwards because the flame is presumed to stay in and around the cavity which occupies a region around the central axis of the piston. On the other hand, the heat loss ratio, namely the ratio of lost heat to the heat supplied by the fuel, is larger than in a gasoline engine.

In terms of engineering applications of CFD, high accuracy and affordable computational costs are required and PC clusters are regarded as promising tools. In this study, a Navier Stokes solver using contravariant physical velocity is implemented on a PC Cluster to predict flow in a centrifugal fan volute. Parallelisation is based on the domain decomposition technique with message passing provided by the MPI. Up to eight processors are used. Predicted flow patterns and volute performance agree well with experimental results. In spite of uneven load distribution and complicated communication patterns required in the near-tongue treatment, efficiency per iteration is 0.767 with four processors and 0.760 with eight.

The dynamics of morphological change of the growing film surface during a vertical ballistic deposition is numerically studied by means of a phenomenological model. The model is a phenomenological continuum model, described by a pair of coupled equations of the phase field for a growing film and the density field for ballistic deposited particles. Several computer simulations show that morphological transitions of the growing surface occur on varying phenomenological parameters of the model. Especially, it is found that stable columnar structures are obtained within some ranges of parameters.

We present our computer simulation results on the slow dynamics in magnetic fluids. Magnetic fluids are modeled as an ensemble of interacting ferromagnetic nanoparticles suspended in a viscous fluid. From the Brownian dynamics simulations of the model, it is found that the origin of slow dynamics in magnetic fluids is related to the structure formation of magnetic particles.

We propose a physical model which describes the post-deposition coarsening of coherently strained three-dimensional islands on a flat substrate. In this model, formulated in terms of a set equations of motion for the island volume and position, both Ostwald ripening mechanism and misfit strain-induced elastic effects are taken into account. Large-scale computer simulations demonstrate that the repulsive inter-island elastic interaction causes the island motion, leading to the self-organized formation of a regular array of islands with both uniform size and spacing.

We present two-dimensional computer simulation results of magnetic vortex systems driven by Lorentz force through polycrystalline superconductors with random network structures of twin boundaries. Langevin dynamics simulations of a point vortex model demonstrate that (1) the threshold behavior of I–V curves is observed, (2) the threshold current is a decreasing function of an average superconducting grain size, and (3) the 1/f noise power spectrum of the ensemble-averaged vortex velocity appears near the threshold current.

We propose the Langevin-type microscopic equations of motion for magnetic fluids. Magnetic fluids are modeled as an ensemble of interacting ferromagnetic nanoparticles suspended in a viscous fluid. The present model is described in terms of position vectors of nanoparticles and orientation vectors of their magnetic dipole moments. In this model, forces and torques arising from the magnetic origin and the surrounding fluid flow are included. Effects of non-spherical particle shape are also taken into account. From the Brownian dynamics simulations of the model, it is found that the present model exhibits various microstructure formation processes in magnetic fluids.