In this study, recent researches related to mesh-free/particle methods for fluid structure interaction (FSI) problems are briefly reviewed. Especially an attention is paid on the mesh-free/particle methods for fluid. One of the difficulties of FSI problems by mesh-based methods, such as the finite element method, lies in the collapse of fluid mesh when the structure deforms or moves so largely that the topology of fluid mesh could not be retained nor even the ALE approach could not be applied. In that situation, mesh-free/particle methods have strong potential to overcome this problem as they are free from meshes. In this study, three approaches are introduced, a full particle method for both fluid and structure, a coupled mesh-free/mesh-based method for fluid/a mesh-based for structure and a full mesh-based method for both fluid and structure. The advantages and disadvantages of these methods are discussed.

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An efficient partitioned coupling algorithm for fluid-structure interaction problems was proposed in this paper. Partitioned coupling algorithms, which can treat a structural problem and a fluid dynamics one independently, seem suitable for large-scale computation in a parallel environment because this approach can utilize existing parallel analysis codes. In this paper, an iterative partitioned coupling algorithm was proposed for high performance computing. Numerical example shows the present approach can efficiently perform the analysis of fluid-structure interaction problem accompanied by large structural displacement.

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Numerical methods for simulating flows with phase change recently developed by our group are surveyed. One is the method for condensate flows at high and low Mach numbers. Another is the method for supercritical fluids. These methods are based on the preconditioning method for compressible Navier-Stokes equations, condensation models and a real-gas equation of state (EOS). Since the preconditioning method derived by us allows zero velocity fields without the stiffness, the thermal conduction in solid states are also solvable using the present method. The procedure is briefly expressed and some practical calculations as industrial applications are introduced.

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Wet-steam flows through steam-turbine cascades in a multiple stage are numerically simulated. As numerical examples, wet-steam flows through a single cascade channel developed by Bakhtar is calculated and the calculated results are compared with the experiments, and wet-steam flows through turbine cascades in multi stage developed by Mitsubishi Heavy Industries are calculated assuming unsteady states. Finally, the effect of the wetness in the stages are numerically predicted. Fundamental equations contain conservation laws of water vapor, water liquid, the number density of nucleus, momentum equations, and the energy equation. The SST turbulence model is employed to predict the eddy viscosity. The classical condensation theory is used for modeling homogeneous and heterogeneous condensations. These equations are solved by the fourth-order compact MUSCL TVD scheme and LU-SGS scheme.

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Parallel computing is inevitable for analyzing practical problems, which require complicated modeling and accordingly huge computing resources. However, the implementation is time consuming and bug causing. In addition, the optimization strategy for each hardware is no longer unique. For developing the parallel FE fluid analysis code, the present study has employed "the HPC middleware". Efficiency and reliability of the development process with the HPC middleware will be discussed.

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In this paper, impact experiments using a simple head model and FE simulations were conducted. The experiments and FE simulations were performed to identify the most suitable property of CSF regarded as incompressive solid in some suggested properties of CSF. By the result, the most suitable property is the property suggested by Zhou et al. in this attempt. The property was also applied to our head FE model and the FE simulation using the model represented good agreement with the cadavaric experiments by Nahum et al.

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The intracranial pressure change and the propagation of the pressure wave are strongly affected by how to give the impact loading on the head. A causal relationship between the extent of brain damage and the method of giving impact loading should be investigated experimentally. The finite element method for human head models can be of major assistance to researchers in the study of brain injuries. In this study some parameters of the impact loading for constant impulse and constant energy shocks of variable force duration are prepared, and intracranial pressure of the impact side and the opposite side of the impact are simulated.

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Groundwater flow and mass transport analyses in fractured rock play a central role in the performance assessment of the High-Level Radioactive Waste repository. Recently the FFDF code, a Monte Carlo code for mass transport in fractured rock, was developed by UCB, which is able to calculate groundwater flow and mass transport by PC for a host rock of 10 square meters, with hundreds of fractures. In this study, FFDF code was transplanted to Earth Simulator and groundwater flow and mass transport analyses for a large-scale fracture network with more than a hundred thousand fractures are performed. The computational capability needed for repository scale simulation is evaluated by using the FFDF code.

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A scalable and high performance parallel visualization library has been developed for large-scale simulations on the Earth Simulator. Flexible parallel visualization models are provided to fit for different requirements of simulations. Meanwhile, a variety of mesh types in numerical simulations are applicable, covering particles, structured grids, and complicated unstructured and hybrid grids. Many techniques were employed to improve the visualization quality. Moreover, all the modules have been optimized according to the hardware features of the Earth Simulator. Good visualization images and high speedup performance on the Earth Simulator demonstrated the feasibility and effectiveness of our library.

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This paper investigates on the interface stresses of an elastic conical-form solid cylinder inserted in a rigid conical-form hole. It is assumed that the contact surface between the solid cylinder and the rigid hole is perfect bonding or sliding conditions. A method of solution is presented for the problem by applying Green's functions for axisymmetric body force problems of an elastic half space. The interface stresses are shown by numerical calculations.

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Dissimilar material joints have singularities created by discontinuities in material properties across an interface. For this reason, it is difficult to predict accurate stress by using conventional FEM. An enriched finite element method is one method developed for solving this problem. In this study, we try to apply an enriched finite element method to study the stress intensity factor in case of applied shear loading on its boundary. Furthermore, a relationship between the stress intensity factor and model thickness is presented.

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Characteristics of singular field around interface edge between elastic and elastic-plastic joint were investigated theoretically especially focusing on the applicability of elastic-plastic/rigid material interface model. Finite element simulations have been conducted to accomplish the quantitative examinations with the theoretical results. The simulation results of stress distribution clearly show that the singular fields exist around the interface edge between the elastic and elastic-plastic joint. Separable form functions of stress distribution were examined around the interface edge. The order of singularity for the elastic/elastic-plastic material joint can be predicted using the elastic-plastic/rigid material interface model.

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Great advancement has been achieved in the analysis of specific microstructure instability causing a loss of creep strength at 550℃ and above. The loss of creep rupture strength has extensively been investigated for a number of tempered martensitic 9 to 12 Cr steels. The proposed mechanisms are due to the occurrence of microstructure degradation during creep exposure, especially due to inhomogeneous or preferential recovery of martensitic microstructure in the vicinity of prior austenite grain boundaries. The precipitation of Z-phase, M_6X carbonitrides and Fe_2(W,Mo) Laves phase during creep promotes inhomogeneous microstructure evolution.

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The present study has applied Hori and Kameda's stress inversion method to the estimation of elasto-plastic stress distributions in Al-Mg polycrystalline materials. The method can estimate 2D elasto-plastic stress distributions from deformation distributions measured in a structure by using only the elastic moduli of the material of the structure. First, computer codes have been developed based on the present stress inversion method. Then, elasto-plastic 2D FEM analyses of stress concentration problems caused by elliptic holes and rectangular inclusions were made. Comparison of the results obtained by the FEM analyses and the stress inversion method showed that the stress inversion method can estimate elastic and elasto-plastic stress distributions from deformation/strain distributions with reasonable accuracy. Finally, the elasto-plastic stress distributions in Al-Mg were estimated by using deformation distributions measured by the digital image correlation method and it was found that stress concentration occurred near triple junctions of grain boundaries.

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