Theoretical and Applied Mechanics Japan
Online ISSN : 1349-4244
Print ISSN : 1348-0693
ISSN-L : 1348-0693
58 巻
選択された号の論文の35件中1~35を表示しています
I. Solid and Structural Mechanics
II. Dynamics and Optimization
III. Mechanics in Geophysics
  • Daisuke INAZU, Tomoyuki HIGUCHI, Kazuyuki NAKAMURA
    2010 年 58 巻 p. 101-112
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    An evolutionary algorithm (EA) is applied to a regional ocean tide model to optimize a boundary condition and a physical parameter in the model. Bathymetry is one of the boundary conditions in ocean models and is frequently given by global sea depth data based on estimations derived from satellite gravity observations. The accuracy of the satellite-derived depth data is often insufficient for accurate ocean tide simulations. We apply the EA to modify the mean depth in specific regions of the Alaska Panhandle, USA. The mean depth in these regions is optimized to be close to that of the multibeam-derived depth data which is generally more accurate than the satellite-derived data but has sparse spatial coverage. Also, a region with large errors of the satellite-derived data is successfully found and corrected through the optimization. The EA has prospects for the correction of erroneous boundary conditions for accurate ocean modeling.
  • Noa MITSUI, Takane HORI, Shin’ichi MIYAZAKI, Kazuyuki NAKAMURA
    2010 年 58 巻 p. 113-120
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    Frictional parameters at the plate interface during an earthquake generation cycle can be estimated from a model based on laboratory-derived rate- and state-dependent friction laws by using sequential importance sampling (SIS, a type of particle filter) to develop a quantitative model for forecasting earthquakes. We can use daily synthetic afterslip data for one year from the day after an earthquake to accurately determine steady state velocity dependence (a-b)σ, but not characteristic slip distance dc. However, if we use data for one day from the commencement of afterslip, with high time resolution, dc can also be determined accurately if noise levels are low enough. When dc is small, the information that allows determination of dc is included only in the data within one day after an earthquake. Although at high time resolution noise levels are high and comparable in amplitude to the signal, advances in GPS technology will decrease noise levels and allow dc to be determined more accurately.
  • Tetsuya TAKEMI, Kenichi KUSUNOKI, Keiji ARAKI, Toshiaki IMAI, Kotaro B ...
    2010 年 58 巻 p. 121-130
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    The present study numerically simulates the development and evolution of a line of misocyclones embedded in winter convective storms and examines the representation and localization of surface strong winds due to the misocyclones by conducting high-resolution simulations. A case on 2 December 2007 over the Shonai Plains is chosen for the present analysis. The 120-m grid simulation well represents well-defined multiple misocyclones in a cloud band, where horizontal wind shear is significant. Since the environmental low-level atmosphere is very unstable owing to cold air over the warm ocean, the strength of convective clouds is significant enough to enhance the misocyclones. The present simulation captures observed high wind speeds and their local scales due to the strong misocyclones. A finer-grid (i.e., 80 m) simulation, however, does not better resolve and represent the vortices and associating gusty winds. These contrasting results suggest that the representation of meteorological disturbances that spawn them is primarily important.
  • Yuki TANIGUCHI, Hideaki KITAUCHI, Michio YAMADA
    2010 年 58 巻 p. 131-143
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    Numerical nonlinear solutions are obtained for steady flow in a rotating polar cap with inflow and outflow. Although an analytical linear solution has no closed vortex in the polar cap, the nonlinear solution has a closed vortex in a central area of the polar cap even when the inflow rate is small. As the inflow rate increases, the area of the closed vortex first increases and then keeps a nearly constant value, and finally decreases when the steady flow becomes linearly unstable.
  • Yoshinobu WAKATA
    2010 年 58 巻 p. 145-151
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    The ocean bottom turbulent boundary layer is investigated using a large eddy simulation (LES) model. The time evolution of the turbulent boundary layer and the vertical and horizontal structure are studied. Derived parameters such as the boundary layer depth, effective eddy viscosity, and energy dissipation rate are estimated from analysis of the model output. Comparison with an observational research is also performed.
  • Hitoshi IMAI, Hideo SAKAGUCHI, Toshiki TAKEUCHI
    2010 年 58 巻 p. 153-164
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    In the paper the Cauchy problem for the two-dimensional Laplace equation is solved. The domain is annular and Cauchy data are given on the first quadrant part of the external circular boundary. In the case where the solution is part of a global function direct numerical computation by IPNS(Infinite-Precision Numerical Simulation) is successful. On the other hand, in the case where the solution is part of a function with singularity direct numerical computation fails. In this situation some kinds of Tikhonov regularization are adopted. Numerical results show that regularization with second derivatives is efficient for the stable numerical computation.
IV. Heat Transfer and Fluid Mechanics
  • Kenzo SATO
    2010 年 58 巻 p. 167-175
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    Theoretical analysis about the transient heat conduction of a very long hollow confocal elliptical cylinder in comparison with its cross-section, i.e. an infinite hollow confocal elliptical cylinder, is given by the use of the method of separation of variables. A constant initial temperature in the cylinder and no heat flow along the cylinder length are assumed, and the analysis is carried out in the two dimensional domain. The complete form of solution is presented by a Mathieu function series for the case where the cylinder is insulated on its inner surface and surrounded by the medium of a constant temperature outside its outer surface. The heat-conduction solution for an infinite hollow concentric circular cylinder is derived as the limit of the present investigation's accomplishment. Some numerical results are given in a table and figures. In the previous paper4), as the process for leading to a special case (an infinite full circular cylinder) was inappropriate though the final limiting form of equation has no mistake in it, the corrected way to it is added as an appendix in this report.
  • Tomoaki ITANO, Sadayoshi TOH, Kai SATOH
    2010 年 58 巻 p. 177-183
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    Applying bifurcation analysis in conjunction with direct numerical simulation, two distinct nontrivial equilibrium states in plane Poiseuille flow are obtained. The two states are distinguished by the symmetries imposed. One of these states is of the same form as the exact coherent structure obtained previously by Waleffe. The other state has a pair of counter-rotating streamwise vortices that can develop across the channel midplane, and may provide an exact expression for largescale structures observed in fully turbulent flow. A truncated dynamical model describing these states predicts that streaky components induced by large-scale circulations spanning the whole of the channel width may survive even in the limit of infinite Reynolds number.
  • Yoshinobu INADA, Hideaki TAKANOBU
    2010 年 58 巻 p. 185-195
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    Collective motion control of air vehicles is an effective method to realize multifunctional and high-reliable aerial surveillance system by combining the various functions of numbers of air vehicles and by utilizing high degree of redundancy. In this study, the biologically-inspired collective motion control is incorporated to realize the collective motion of air vehicles. This control employs simple local interactions among agents in a group, and the properties of collective motion are determined by several interaction parameters, e.g. the size of interaction field around the agent and the number of neighbors of the agent engaged in the interaction at the same time. The dependency of collective motion of air vehicles on such interaction parameters is investigated here and the key interaction parameters are clarified which affect significantly the motion or shape parameters of the group. The existence of correlations among several motion or shape parameters is also clarified.
  • Tsuyoshi YASUNOBU, Yumiko OTOBE, Hideo KASHIMURA
    2010 年 58 巻 p. 197-203
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    When the underexpanded supersonic jet impinges on the obstacle, it is well known that the self-induced flow oscillation occurs under the specific condition, namely the pressure ratio in the flowfield, the position of an obstacle and so on. This oscillation is related with the noise problems of aeronautical and other industrial engineering so that the characteristics and the mechanism of self-induced flow oscillation have to be cleared to control the various noise problems. This paper aims to clear the characteristics of oscillation frequency, pressure fluctuation on the surface of a cylindrical body through experiments. From the experimental results, it is clear that the Strouhal number of the Mach disk and standoff shock wave depend on the size and position of the obstacle.
  • Kazuo MAENO, Hirokazu ENDO, Kazuya OHMURA, Masanori OTA
    2010 年 58 巻 p. 205-212
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    When a high speed train enters a long tunnel, compression wave is generated in front of the train. This compression wave propagates in the tunnel at the speed of sound. When the wave arrives at the end of the tunnel, a pulsed compression wave, called ‘tunnel micro-pressure wave’, is radiated from the exit. This micro-pressure wave causes environmental problems especially in high-speed Shinkansen Expresses. In recent years, however, with the improvement of vehicle performance the running speed of train is increasing, and this problem of the tunnel pressure wave has also occurred by conventional limited express. This study deals with the pressure wave formation and propagation phenomena by the experiment using an apparatus with diaphragmless driver acceleration, and small train nose models of limited express in combination with a short tunnel and a station model.
  • Yumiko OTOBE, Hideo KASHIMURA, Toshiaki SETOGUCHI
    2010 年 58 巻 p. 213-218
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    The numerical results of supersonic jet are non-dimensionalized by the nozzle exit diameter for the analysis of jet structures. Recently, the micro-nozzles of milli-m or micro-m size are used in industrial engineering. In these cases, it seems that the similarity in jet structures has not been guaranteed. This paper aims to clarify the influence of the nozzle diameter on the structure of under-expanded supersonic jet by numerical analysis. In this study, the jet structure, the location and the diameter of Mach disk, the sonic line and the boundary layer in the nozzle are analyzed decreasing the nozzle diameter from 12.7 mm.
  • Susumu KOBAYASHI, Takashi ADACHI, Tateyuki SUZUKI
    2010 年 58 巻 p. 219-225
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    The discrepancy between theory and experiment for weak oblique shock reflection is well-known as the von Neumann paradox. Until recently, this paradox has been considered to be a specific phenomenon restricted to weak shock reflection. However, a series of experiments for strong shock wave demonstrates that this is not the case. In particular, for a reflecting wedge angle slightly less than the theoretical transition wedge angle, the dynamic transition from regular to Mach reflection occurs during incident shock propagation. This result indicates that the phenomenon can be regarded as neither self-similar nor pseudosteady, and contradicts the original assumptions by von Neumann. The present paper investigates this phenomenon for the incident shock Mach number Mi = 1.915 and concentrates on the dynamic transition. The characteristics of triple-point and wave angles are compared for both smooth and rough surfaces. Surface roughness acts to suppress the transition to Mach reflection. A remarkable difference in the behavior of the reflection angle is observed between smooth and rough wedges.
  • Katsunori YOSHIMATSU, Naoya OKAMOTO, Marie FARGE, Kai SCHNEIDER
    2010 年 58 巻 p. 227-233
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    Two nonlinear filtering methods for extracting coherent structures from direct numerical simulation data of isotropic turbulence are compared. One is based on the orthonormal wavelet decomposition, called coherent vortex extraction (CVE) method, and the other is based on the Fourier decomposition, called Fourier nonlinear filtering (FNF) method. We examine contributions of structures extracted by applying these methods to turbulent flows. Coherent structures extracted by using the CVE method, reconstructed from only 3.6 % of the degrees of freedom, preserve the vortex tubes as well as statistical quantities of turbulence. In contrast, the structures extracted by using the FNF method, represented by 7.3 % of the degrees of freedom, only well preserve low-order statistical quantities, e.g., energy, enstrophy and the energy spectrum in the inertial range, but smooth out the vortex tubes.
  • Takeshi KATAOKA
    2010 年 58 巻 p. 235-242
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    The Rayleigh-Benard problem for a gas in the continuum limit with finite temperature difference is reinvestigated. It was recently shown that the behavior of a gas with finite temperature difference is not described by the usual NS equations but by the SB equations, which are derived systematically from the Boltzmann equation in the continuum limit. The SB equations include the thermal-stress terms which do not appear in the NS equations. In the present study, we investigate the linear stability of the quiescent state of the system on the basis of the SB equations. The results show that the critical Rayleigh number for the onset of instability in the framework of the SB equations is always greater than that in the framework of the NS equations.
  • Norio KONDO
    2010 年 58 巻 p. 243-250
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    We present numerical results for hydrodynamic oscillations in in-line and cros-flow directions of an elastically supported square cylinder, which is placed in a uniform flow, by three-dimensional computation. In the case of the in-line oscillation which occurs at the low Scruton number, there are two characteristics of oscillations in a range of low reduced velocities. In order to catch such oscillations, a numerical computation is achieved by means of the finite element method and the arbitrary Lagrangian-Eulerian method. In addition, numerical stabilization of solutions of the Navier-Stokes equations is performed by a third-order upwind scheme. From our numerical results, we clearly show hydrodynamic characteristics of the oscillating squre cylinder and discuss about the response mechanism.
  • Kazuyasu SUGIYAMA, Helmut RATHGEN
    2010 年 58 巻 p. 251-260
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    An acoustic dynamics of a circular micro-meniscus is theoretically studied. The system involves a perfect gas bubble entrapped in a micro-meter-sized cavity, which is fabricated at the end face of a horizontal plane wall submerged in a viscous incompressible liquid. An unsteady Stokes equation for liquid and a linearized energy equation for gas are solved to determine the micro-meniscus oscillation in an untrasound field. The transfer functions, which connect the meniscus oscillation to the liquid and gas normal stresses on the interface, are derived. The frequency response predicted by the present model is consistent with available experimental data on the amplitude of the interfacial deflection. The viscous damping effect on the resonance behavior is discussed.
  • Takeshi AKINAGA, Masako SUGIHARA-SEKI, Tomoaki ITANO
    2010 年 58 巻 p. 261-270
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    The electrostatic model for osmotic flow across a porous membrane in our previous study (Akinaga et al. 2008)1) was extended to include the streaming potential, for solutes and pores of like charge and fixed surface charge densities. The magnitude of the streaming potential was determined to satisfy zero current condition along the pore axis. It was found that the streaming potential affects the velocity profiles of the pressure driven flow as well as the osmotic flow through the pore, and decreases their flow rates, particularly in the case of large Debye length relative to the pore radius, whereas it has little effect on the reflection coefficients of spherical solutes through cylindrical pores.
V. Numerical Simulation
  • Kou YAMADA, Yoshinori ANDO, Iwanori MURAKAMI, Takaaki HAGIWARA, Yoichi ...
    2010 年 58 巻 p. 273-284
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    In this paper, we examine a design method for control system to attenuate unknown output disturbances using disturbance observers. The disturbance observers have been used to estimate the disturbance in the plant. Several papers on design methods of disturbance observers have been published. Recently, parametrizations of all disturbance observers and all linear functional disturbance observers for plants with any output disturbance were clarified. If parametrizations of all disturbance observers and all linear functional disturbance observers for any output disturbance are used, there is a possibility that we can design control systems to attenuate unknown output disturbances effectively. However, no paper examines a design method for control system using parametrizations of all disturbance observers and all linear functional disturbance observers for plants with any output disturbance. In this paper, in order to attenuate unknown output disturbances effectively, we propose a design method for control system using parametrizations of all disturbance observers and all linear functional disturbance observers for plants with any output disturbance. In addition, control characteristics of the proposed control system are clarified.
  • Takaaki HAGIWARA, Kou YAMADA, Nobuaki NAKAZAWA, Iwanori MURAKAMI, Yosh ...
    2010 年 58 巻 p. 285-293
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    In this paper, we investigate the parametrization of all robust stabilizing multi-period repetitive (MPR) controllers for single-input/single-output time-delay plants. The MPR controllers were proposed by Gotou et al., in order to improve the disturbance attenuation characteristic of the modified repetitive control systems. Yamada et al. proposed a design method of MPR controllers to attenuate wide-frequency disturbance based on the idea of changing time-delay. In addition, Yamada et al. obtained the parametrization of all stabilizing MPR controllers. However, the parametrization of all robust stabilizing MPR controllers for the time-delay plant with uncertainties has not been considered yet. In this paper, we propose the parametrization of all robust stabilizing MPR controllers for time-delay plants with uncertainties. The basic idea of the method is as follows. If the MPR control system is robustly stable for time-delay plant with uncertainties, then the MPR controller must satisfy the robust stability condition. This implies that if the MPR control system is robustly stable, then the MPR controller is included in the parametrization of all robust stabilizing controllers for the plant with uncertainties. Robust stabilizing controllers for the plant include a free parameter, which is designed to achieve desirable control characteristics. If the free parameter is chosen to give the control system robust servo characteristic for periodic reference input, then the controller operates as a robust stabilizing MPR controller. Conversely a MPR controller stabilizing the plant robustly, then the free-parameter is written by an appropriate form. Using this idea, we obtain the parametrization of all robust stabilizing MPR controllers.
  • Reima IWATSU, Hideo TSURU
    2010 年 58 巻 p. 295-300
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    Recently, a new set of coefficients are found for the third-order Yoshida-Ruth type symplectic integration algorithm (SIA). This method has larger stability limit and less phase error than the Ruth's coefficients. We consider trigonometric fitting (TF) method based on this new set of coefficients. %The relationship of TF conditions to the sympliticy order conditions, stability and errors are discussed. This new TF-SIA is compared with the TF methods by Simons for the harmonic oscillator problem.
  • Hayato SUZUKI, Hitoshi MATSUBARA, Yoshitaka EZAWA, Genki YAGAWA
    2010 年 58 巻 p. 301-308
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    In this study, we describe a method for highly accurate three-dimensional analysis of a dynamic elastic problem. The Enriched Free Mesh Method(EFMM) is an improvement over the Free Mesh Method(FMM), a type of meshless method, in term of accuracy. A three-dimensional static problem was analyzed using the EFMM, and we found that its accuracy was better than that of the FMM, with a smaller number of CG iterations. The EFMM was also applied to the dynamic problem and numerical analysis was conducted. We found that the EFMM was a much more effective method than the FMM.
  • Hide SAKAGUCHI, Daisuke NISHIURA
    2010 年 58 巻 p. 309-319
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    In the Discrete Element Method (=DEM), the tangential spring force has the limit according to the Coulomb friction law. And generally for the frictional parameter, the coefficient of static friction is used. However, when the normal force is impulsive, such as the case of collision, it is doubtful to use the parameter based on static friction. Especially for polygonal DEM, friction due to the rotation which is induced by the inertia couple, such as the case of eccentric collision, is very complex but not studied well. Then, we performed two dimensional eccentric collision experiments using polygon plates on a frictionless air table. Polygon motions were recorded with two different frame speed digital cameras; 1) 1,000 frames per second for the overall view, and 2) 125,000 frames per second for the contact point micro view. In comparison with polygonal DEM simulations, the dynamics was analyzed from the kinematics data.
  • Katsuya NAGAYAMA, Junya NITTA, Ichiro MIURA
    2010 年 58 巻 p. 321-324
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    There is a close relation between cancer growth and angiogenesis. While blood vessel supplies nutrition to help cancer cells increase, cancer cells attract growth of the blood vessel simultaneously. Thus they grow by interacting each other. A particle model was introduced to simulate and to clarify this relation. 2D model was developed and was applied to the blood vessel network of vasculogenesis in an egg comparing with experimental result and another simulation result. The model was extended to 3D model of cancer growth and angiogenesis. There blood vessel network growth, nutrition transportation, cancer cell movement and its increase were taken into consideration. Basic results that cancer grows as blood vessel network grows were obtained, and it means a first step model is established qualitatively. Next step will be model improvement close to real phenomenon and quantitative verification by comparing with real cancer growth obtained by in vivo imaging.
  • Gaku HASHIMOTO, kenji ONO
    2010 年 58 巻 p. 325-342
    発行日: 2010/02/27
    公開日: 2010/09/01
    ジャーナル フリー
    We show that a fluid-structure coupling method based on a fixed Eulerian mesh using the level set function is applicable to fluid-structure interaction (FSI) problems involving incompressible viscous fluids and thin elastic structures. The coupling method was originally proposed for large-deformation FSI analyses of high-speed compressible inviscid flows and thin structures such as airbags. We introduce a novel interface-treatment technique that uses virtual particles with level sets and structural normal velocities to enforce the kinematical condition at the fluid-structure interface on a fluid fixed mesh. The virtual particles also have structural tangent velocities so as to impose no-slip conditions at the interface. Application of the method to finite-deformation FSI problems, and comparison of the results with those obtained by the conventional moving ALE mesh-based scheme show the adequacy of the method. It is confirmed that the appearance of the flow and geometry of the interface are similar to those for the ALE scheme.
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