Simplified Approach to Evaluate Cavitation Intensity Based on Time Information on Imposed Pressure in LiquidHiroyuki Kawashima; Hiroyuki Kogawa; Masatoshi Futakawa; Nobuatsu Tanaka, Last, Cavitation damage is an important research topic in fluid–structure interactions, such as those being studied using the mercury target for the pulsed neutron source at the Materials Life Science Experimental Facility/Japan Proton Accelerator Complex. Hence, the estimation of cavitation damage (cavitation intensity) is required from the perspective of structural integrity. The results of previous studies suggest that the maximum radii of cavitation bubbles immediately prior to collapse are related to cavitation intensity. Therefore, we propose a method for estimating the maximum radius from the time information by measuring the vibrations of structure walls that are induced by collapsing cavitation bubbles in a confined liquid. In this study, we used a magnetic impact testing machine to experimentally investigate the cavitation bubble dynamics, directly observe the bubble collapsing behavior, and measure the induced vibration. We experimentally confirmed that the time information is useful in the estimation of the maximum radii of bubbles. Moreover, we theoretically derived a simple evaluation formula to estimate the maximum radius from the time responses of the imposed pressure in a confined liquid in a structure., MDPI AG
Fluids, 06 Dec. 2024
Study on Correlation between Pressure Time-response and Cavitation Damage
Yusuke NAKAZONO; Hiroyuki KAWASHIMA; Hiroyuki KOGAWA; Nobuatsu TANAKA; and Masatoshi FUTAKAWA, Corresponding, Japanese Society for Experimental Mechanics
International Workshop on Advanced Experimental Mechanics for Students and Young Researchers 2023 (IWAEM’23), Nov. 2023
Study on impact damage caused by cavitation bubble collapse
Hiroyuki Kawashima; Hiroyuki Kogawa; Nobuatsu Tanaka and Masatoshi Futakawa, Corresponding
Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023 (ATEM-iDICs '23), Oct. 2023, [Reviewed]
Study on damage evaluation using cavitation-bubble collapsing time
Hiroyuki Kawashima; Hiroyuki Kogawa; Masatoshi Futakawa; Nobuatsu Tanaka; ChiekoKuji; Hitoshi Soyama, Corresponding
International Conference on Multiphase Flow, Apr. 2023, [Reviewed]
Spattering Behavior Induced by Cavitation Bubble Collapsing Nearby Gas-Liquid Interface
Kawashima; H.; Kurosawa; T.; Teshigawara; M.; Naoe; T.; Tanaka; N.; Futakawa; M.; Kogawa; H., Corresponding
Advanced Experimental Mechanics, Aug. 2022, [Reviewed]
Experimental and Numerical Observation On Spattering Behavior Induced by Cavitation Bubble Collapsing Nearby Gas-liquid Interface
Hiroyuki KAWASHIMA; Takuma KUROSAWA; Makoto TESHIGAWARA; Takashi NAOE; Nobuatsu TANAKA and Masatoshi FUTAKAWA, Corresponding
16th International Symposium on Advanced Science and Technology in Experimental Mechanics, Nov. 2021, [Reviewed]
Observation of melting metal behavior caused by high power pulsed laser injection using high speed photography technique
Yuji USHITSUKA; Makoto TESHIGAWARA; Takashi NAOE; Masatoshi FUTAKAWA; Koichi SARUTA; Toshiharu MURAMATSU; Tomonori YAMADA; Nobuatsu TANAKA; Kazuhiko YAMASAKI, Corresponding
14th International Symposium on Advanced Science and Technology in Experimental Mechanics, Nov. 2019, [Reviewed]
Effect of wall boundary on growing and collapsing behaviors of cavitation bubble
S. Kawamura; T. Naoe; N. Tanaka; and M. Futakawa, Corresponding
14th International Symposium on Advanced Science and Technology in Experimental Mechanics, Nov. 2019, [Reviewed]
Evaluation Growing and Collapsing Behaviors of Cavitation Bubbles under Flowing Condition
S. Kawamura; T. Naoe; N. Tanaka; and M. Futakawa, Corresponding
Advanced Experimental Mechanics, Aug. 2019, [Reviewed]
Pulsed Pressure Induced Cavitation Erosion in Mercury Narrow Channel under Flowing Conditions
Takashi NAOE; Hiroyuki KOGAWA; Nobuatsu TANAKA and Masatoshi FUTAKAWA
Advanced Experimental Mechanics, Aug. 2019, [Reviewed]
Aiming at disposal of radio-active waste, laser cutting development to suppress the sputter particles
Takashi Naoe; Makoto Teshigawara; Masatoshi Futakawa; Haruki Mizutani; Toshiharu Muramatsu; Tomonori Yamada; Yuji Ushitsuka; Nobuatsu Tanaka; Kazuhiko Yamasaki
The 8th International Congress on Laser Advanced Materials Processing, May 2019, [Reviewed]
Visualization of Cavitation Growing and Collapsing Behaviors in Narrow Channel,
S. Kawamura; T. Naoe; T. Ikeda; N. Tanaka; and M. Futakawa, Corresponding
13th International Symposium on Advanced Science and Technology in Experimental Mechanics, Oct. 2018, [Reviewed]
Optimization of the Swirl Gas Microbubble Generator for a Liquid Mercury Target Vessel
Tsubasa IKEDA; Hiroyuki KOGAWA; Takashi NAOE; Shunsuke KAWAMURA; Nobuatsu TANAKA and Masatoshi FUTAKAWA, Corresponding
13th International Symposium on Advanced Science and Technology in Experimental Mechanics, Oct. 2018, [Reviewed]
Three Dimensional Numerical Analysis of Two Phase Flow Separation Using Swirling Fluidics
Mizunar Rahman, Nobuatsu Tanaka, Seiichi Yokobori, Corresponding
Energy and Power Engineering, 2013, [Reviewed]
高出力パルス核破砕中性子源におけるキャビテーション
混相流, 2011, [Reviewed]
Improvement of conservative property and interface resolution of mesh-based two-phase flow simulation algorithms for splashing fluid behaviorsNobuatsu Tanaka; Ryo Maseguchi; Takuya Ogawara, This study is concerned with improvement of numerical code called CRIMSON (Civa Refined Multiphase SimulatiON), which has been developed to evaluate multi-phase flow behaviors based on the recent CFD (computational fluid dynamics) techniques. The CRIMSON employs a finite-volume method combined with the high order interpolation scheme, CIVA (cubic-interpolation with area/volume coordinates). The CRIMSON solves gas-liquid two phases by a unified scheme of CUP (combined unified procedure). The conventional CIVA method has two problems of losing interface sharpness in long-term calculation and non-conservativeness. In this study, the problems were solved by introduction of the ideas of the level set method and the phase field method. We verified our method by applying it to some popular benchmark problems of single bubble rising and collapse of water column problems. (c) 2010 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
NUCLEAR ENGINEERING AND DESIGN, Dec. 2010,
[Reviewed] メッシュ法・粒子法のハイブリッド・アプローチによる砕波・液滴飛散の数値解析田中伸厚; 西村健; 渡辺史紀; 森治嗣, Lead, This study is concerned with extension of numerical code called CRIMSON (Civa RefIned Multiphase SimulatiON), which has been developed to evaluate multi-phase flow behaviors based on the recent CFD (computational fluid dynamics) techniques. The CRIMSON employs a finite-volume method combined with the high order interpolation scheme, CIVA (cubic-interpolation with area/volume coordinates). The CRIMSON solves gas-liquid two phases by a unified scheme of CUP (combined unified procedure). The conventional CIVA method has a problem of loosing interface sharpness in long-term calculation. In this study, the problem was solved by introducing the idea of the phase field method. For numerical analyzing splashing fluid, we also introduced the SPH particle method to the CRIMSON., The Japan Society of Mechanical Engineers
日本機械学会論文集、Ｂ編, 2010
Bubble flow simulations in target vesselKatsuhiro Haga; Hiroyuki Kogawa; Takashi Wakui; Takashi Naoe; Masatoshi Futakawa; Shogo Yamazaki; Nobuatsu Tanaka, Target vessel wall being damaged by pitting caused by pressure waves generated when pulsed high-power beams are injected is a crucial issue in the realization of a pulsed high-power mercury target for spallation neutron sources. The injection of micro-bubbles into mercury is a prospective technology for use in mitigating the pressure wave and the resulting pitting. The bubble flow field in an actual target vessel was numerically examined and the optimal conditions for bubble injection were investigated. The results indicated the possibility of the bubbles being distributed over the core regions when they are injected in the appropriate position according to their diameter. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Feb. 2009,
[Reviewed] Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysisToru Masuzawa; Akiko Ohta; Nobuatu Tanaka; Yi Qian; Tomonori Tsukiya, The effect of the hydraulic force oil magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 141/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump., SPRINGER TOKYO
JOURNAL OF ARTIFICIAL ORGANS, 2009,
[Reviewed] Numerical analysis of swirling flow inducing gas entrainment by dynamic SGS model based on LISEA
N.Tanaka; T.Taguchi; Y.Motoyama; H.Ohshima, Lead
Comput. Fluid Dynamics J., 2008, [Reviewed]
Mitigation technologies for damage induced by pressure waves in high-power mercury spallation neutron sources (II)—bubbling effect to reduce pressure wave—Masatoshi Futakawa; Hiroyuki Kogawa; Shoichi Hasegawa; Takashi Naoe; Masato Ida; Katsuhiro Haga; Takashi Wakui; Nobuatsu Tanaka; Yoichiro Matsumoto; Yujiro Ikeda, Liquid mercury was suggested to be used as target material for high-power pulsed spallation neutron sources. In order to realize the high-power target, however, the pressure wave is a critical issue, which is caused by the thermal shock in mercury and causes cavitation at the moment when highly intense proton beams bombard mercury. R and D on pressure wave mitigation technologies is carried out for Japan Spallation Neutron Source (JSNS
1MW/25 Hz). Microbubble injection into the mercury is one of prospective technologies to mitigate the pressure wave. The microbubble effect was experimentally investigated from the viewpoint of pitting damage due to the cavitation in the mercury loop with an electro-magnetic impact testing machine (MIMTM) and numerically examined from the viewpoint of bubble dynamics. In the present study, we confirmed that the microbubble injection is very effective to reduce pitting damage and the amplitude of negative pressure, which causes explosive growth of cavitation bubble. © 2008 Taylor and Francis Group, LLC.
Journal of Nuclear Science and Technology, 2008
NUMERICAL ANALYSIS OF CAVITATION EROSION USING GAS-LIQUID-SOLID UNIFIED METHOD WITH CIVA
R.Maseguchi and N.Tanaka, Corresponding
Proc. 3rd Asian-Pasific Congress on Computational Mechanics, Dec. 2007
THEE-DIMENSIONAL SIMULATION OF RED BLOOD CELLS USING SPH AND ITS VISUALIZATION
N.Nakamura and N.Tanaka, Corresponding
Proc. 3rd Asian-Pasific Congress on Computational Mechanics, Dec. 2007
Numerical analysis of thermal-hydraulic behaviors in SI system
Y. Omayu; N.Tanaka; and M.Mori, Corresponding
Proc. 15th Int. Conf. on Nuclear Engineering (ICONE-15), Nagoya, Japan., Apr. 2007, [Reviewed]
Numerical Simulation of Mercury Cavitation in magnetic impact testing machine
N. Tanaka and M.Futakawa, Lead
Proc. 6th Int. Symp. on Cavitation, Wageningen, Netherlands., Sep. 2006
Three-dimensional simulations of microscopic blood flow using SPH method
N. Tanaka; Y. Hayakawa and T. Masuzawa, Lead
5th World Congress of Biomechanics, Munich, Germany., Jul. 2006
A simple but efficient preconditioning for conjugate gradient Poisson solver using Haar waveletN Tanaka, This paper describes a wavelet-based preconditioning technique for conjugate gradient method for linear systems derived from the Poisson equation. The linear systems solved with a conventional iterative matrix solver resulted in a marked increase in computing time with respect to an increase in grid points. Use of our wavelet-based technique leads to a matrix with a bounded condition number so that computing time is reduced significantly. In this study, one of the simplest wavelets, the Haar wavelet, is used for the purpose of developing a simple but efficient preconditioning algorithm. Simple wavelets having low data communication property such as the Haar wavelet are expected to be suitable for the purpose of improving computing performance. In this study, we also pay attention to the basic characteristics of the Haar-wavelet-based preconditioning method for a Poisson equation solver., WORLD SCIENTIFIC PUBL CO PTE LTD
INTERNATIONAL JOURNAL OF WAVELETS MULTIRESOLUTION AND INFORMATION PROCESSING, Jun. 2006,
[Reviewed] Numerical analysis of mercury cavitation in MW-scale spallation neutron source systemN Tanaka; M Suzuki; M Futakawa, We are developing a new numerical analysis method for elucidating and predicting the cavitation phenomena in mercury, which make a controversial impact on the development of the MW-scale spallation neutron source systems. The method is a unified methodology for liquid-gas two-phase problem based on the Cubic Interpolation Volume/Area Coordinates (CIVA) method. Since the Combined Unified Procedure (CUP) method is used for basis algorithm and the finite volume method for discretization, the method enables the numerical analysis of multi-phase flow in technologically complex systems. With the aim of the cavitation analysis, the method introduces the following two methods into the code: a generalized equation of state, which unifies the liquid and gas equations of state, and a model that can represent a pressure change caused by the phase change. We analyze the cavitation problem in mercury and compare the results with the Rayleigh-Presset theoretical solution. (c) 2006 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Jun. 2006,
[Reviewed] CIVA法を用いたキャビテーションの数値解析
混相流特集号,混相流研究の進展I, Apr. 2006, [Reviewed]
Conservative CIVA based on finite volume method
Lead
Comput. Fluid Dynamics J., Jan. 2006
MICROSCOPIC-SCALE SIMULATION OF BLOOD FLOW USING SPH METHODNobuatsu Tanaka; Tatsuo Takano, We have developed a microscopic blood model based on the Smoothed Particle Hydrodynamics (SPH) method. In the model, plasma fluid is discretized by SPH particles, and a red blood cell (RBC) is expressed by internal SPH particles surrounded by elastic membrane particles. For verifying the model, we numerically analyzed two popular phenomena of blood flow. One is the tank-tread motion of an RBC under a constant shear field. The numerical results are agreed well with the experimental data and the tank-tread motion of RBC is well reproduced. The other is the axial migration or pinch effect of RBCs in Poiseuille flow. From the numerical results, we find that the axial migration effect becomes weaker as the viscosity of cell internal fluid becomes higher. The reason is because the RBC motion changes from tank-tread motion to rigid body rotation (from axial migration effect to pinch effect) as the cell contents become thick. From these results, it is confirmed that our blood model based on the SPH method can well express microscopic and rheological properties of RBCs., WORLD SCIENTIFIC PUBL CO PTE LTD
INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS, Dec. 2005,
[Reviewed] Numerical Simulation of Mercury Cavitation in MW Scale Spallation Neutron Sources
N.Tanaka; M.Futakawa and M.Suzuki, Lead
Proc. Int. Conf. on Accelerator Applications, Venice, Italy., Aug. 2005
Volume-preserving semi-lagrangian algorithms For multi-dimensional pollutant advection
N. Tanaka; S. Tsunoyama, Lead
Comput. Fluid Dynamics J., Apr. 2005, [Reviewed]
Error estimation of numerical solutions of linear convection-diffusion problems
N.Tanaka; Y.Motoyama, Lead
Int. J. Comput. Fluid Dynamics, Jan. 2005, [Reviewed]
Sensitivity Analysis of Numerical Results of One- and Two-Dimensional Advection-Diffusion Problems
Y.Motoyama; N.Tanaka, Last
J. Nucl. Sci. Technol.,, Jan. 2005, [Reviewed]
離散要素法を用いた微小循環内の血流シミュレーション
岩田賢; 田中伸厚; 増澤徹, Corresponding
ライフサポート, 2005, [Reviewed]
随伴感度解析法に基づく非線型移流拡散方程式の数値解の誤差評価田中 伸厚; 本山 和道, Corresponding, In this study, we present a new numerical method to analyze quantitatively the error of numerical solution by using the adjoint sensitivity analysis method and the modified equation approaches. If a reference case of typical parameters is once calculated with the method, no additional calculation is required to estimate the results of the other numerical parameters such as those of more detailed resolution. Furthermore, we can estimate the strict solution from the sensitivity analysis results and can quantitatively evaluate the error of numerical solutions based on only the numerical procedures., The Japan Society of Mechanical Engineers
日本機械学会論文集, 2005,
[Reviewed] Accurate and robust fluid analysis using cubic interpolation with volume/area coordinates (CIVA) method on unstructured gridsNobuatsu Tanaka; Toshiteru Yamasaki; Takaya Taguchi, This paper concerns the cubic interpolation with volume/area coordinates (CIVA) method, which is an extension of the cubic interpolation profile (CIP) to a triangular or tetrahedral mesh system, implemented in an unstructured and fixed (Eulerian) mesh-based finite-volume solver. First, we briefly explain the accuracy of and the results of stability analysis by CIVA. Then, to demonstrate the accuracy and robustness of the algorithm, we solve two-dimensional benchmark problems of incompressible lid-driven recirculating flow in square and triangular cavities. In addition, a two-dimensional vortex-driven flow is solved in order to analyze the conservative property of CIVA. Finally, an example of an industrial application of CIVA method is described. These numerical experiments demonstrate the high capability of the method and that it is sufficiently robust for complex industrial applications.
JSME International Journal, Series B: Fluids and Thermal Engineering, Nov. 2004,
[Reviewed] Symplectic semi-Lagrangian schemes for unsteady incompressible viscous flow simulations
N.Tanaka; T.Kitayama and T. Shimizu, Lead
Comput. Fluid Dynamics J., Oct. 2004
Symplectic semi-Lagrangian schemes for computational fluid dynamicsN Tanaka; T Kitayama, The symplectic semi-Lagrangian (SSL) method was developed in order to improve the preservation of the physical quantities of the semi-Lagrangian method. In this method, symplectic integrators are adopted in searching for the upstream point in the semi-Lagrangian method. The purpose of this paper is to verify the validity of the SSL method for a simple passive scalar advection (PSA) problem and for a more practical fluid problem, two-dimensional incompressible viscous flow. From the computed results, it is confirmed that the SSL can take a large time-step size over Courant number 2 without losing computational accuracy., TAYLOR & FRANCIS LTD
INTERNATIONAL JOURNAL OF COMPUTATIONAL FLUID DYNAMICS, May 2004
Application of symplectic integrators to discrete vortex methods for Karman vortex problem
Nobuatsu Tanaka and Toshiteru Yamasaki, Lead
Comput. Fluid Dynamics J., 2004
Development of highly accurate interpolation method for mesh-free flow simulations III. Analysis of accuracy and stabilityN Tanaka, A highly accurate interpolation method, CIVA, improves the accuracy of mesh-free and grid-less methods by taking into consideration first-order spatial derivatives as variables; an approach based on the same idea as that on which CIP is based. In this study, the accuracy and stability of CIVA is evaluated by analytically and numerically. First, the general formulation of CIVA for the n-dimensional case is described. Since CIVA contains the bubble function, we consider the determination methods: constant curvature condition and utilization of another computing point. Then, the relation between the bubble function in the CIVA method and the accuracy and stability is made clear by the analysis based on the Taylor expansion. Some computations of two-dimensional passive scalar advection and advection-diffusion problems are performed for the verification of accuracy and stability. Copyright (C) 2003 John Wiley Sons, Ltd., JOHN WILEY & SONS LTD
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Mar. 2003
Error estimation of finite-difference solution of advection equation for environmental fluid problems
Nobuatsu Tanaka, Lead
Comput. Fluid Dynamics J., 2003
Adaptive grid control methods for CFD: I. Application to natural convection in a square cavity
Lead
Comput. Fluid Dynamics J., 2003
Adaptive grid control methods for CFD: II. Application to multi-grid method and boundary-fitted coordinate system
Nobuatsu Tanaka, Lead
Comput. Fluid Dynamics J., 2003
Application of symplectic integrators to discrete vortex methods
Nobuatsu Tanaka and Toshiteru Yamasaki, Lead
Comput. Fluid Dynamics J., 2002
Hamiltonian Particle Dynamics, CIVA-Particle Method and Symplectic Upwind Scheme
Nobuatsu Tanaka, Lead
Computational Fluid Dynamics Journal, Jan. 2001, [Reviewed]
Parallel processing of Haar-Wavelet-preconditioned conjugate gradient methods
Nobuatsu Tanaka, Lead
Transaction of Japan Society Computational Engineering and Science, 2001, [Reviewed]
Development of Hamiltonian Particle Dynamics(Introduction to the Fundamental Concept)
Transactions of JSCES, 2001, [Reviewed]
Hamiltonain Particle Dynamics 法の開発（シンプレクティック時間積分法の応用）
Lead
日本計算工学会論文集, 2001, [Reviewed]
Development of highly accurate interpolation method for mesh-free flow simulations II. Application of CIVA method to incompressible flow simulationsNobuatsu Tanaka, Lead, This is the second report on the development of a highly accurate interpolation method, which is called cubic interpolation with volume/area (CIVA) co-ordinates, for mesh-free flow simulations. In this paper, the method of determining the c-parameter of CIVA using a constant curvature condition is first considered for the two- and three-dimensional cases. A computation of a three-dimensional passive scalar advection problem is performed for accuracy verification and for comparison with widely used methods. Then, an application algorithm of the CIVA method respecting incompressible fluid simulation is presented. As the incompressible condition based on Lagrangian approaches causes problems, in this paper we consider the condition based on the conventional Eulerian approach. The CIVA-based incompressible flow simulation algorithm enables a highly accurate simulation of many kinds of problems that have complicated geometries and involve complicated phenomena. To confirm the facts, numerical analyzes are executed for some benchmark problems, namely flow in a square cavity, free surface sloshing and moving boundary problems in complex geometries. The results show that the method achieves high accuracy and has high flexibility, even for the flows involving high Reynolds number, complicated geometries, moving boundaries and free surfaces. Copyright (C) 2000 John Wiley & Sons, Ltd., JOHN WILEY & SONS LTD
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Nov. 2000,
[Reviewed] Development of a highly accurate interpolation method for mesh-free flow simulations I. Integration of gridless, particle and CIP methodsNobuatsu Tanaka, Lead, A simple, efficient, flexible and accurate interpolation method, CIVA, is introduced for use with mesh-free methods for flow simulations. The method enables mesh-free cubic interpolation with the local co-ordinate system, such as volume and area co-ordinates, by utilizing the concept of the CIP scheme and allows the development of new highly accurate mesh-free methods. The mesh-free methods integrate the gridless, particle and CIP methods since they have flexibility in the treatment of moving calculation points. For achieving high accuracy with the CIVA method, it is also important to correctly evaluate particle movement. The improvement of the evaluating algorithm is another objective of this study. The validity of the algorithms is confirmed by applying them to the convection and convection-diffusion problems. Since the CIVA-based mesh-free methods enable flexible, efficient and accurate fluid simulation, they make it possible to perform highly accurate simulations of many kinds of problems that involve complicated geometries and phenomena., John Wiley & Sons Ltd
International Journal for Numerical Methods in Fluids, Aug. 1999
Wavelet-preconditioned conjugate gradient Poisson solver and its use in parallel processing
Nobuatsu Tanaka, Lead
Computational Mechanics, 1999
CIVA-粒子法の非圧縮性流体解析への応用
田中伸厚, Lead
日本機械学会論文集 (B), 1999, [Reviewed]
数値流体力学のための高精度メッシュフリー手法の開発
田中伸厚, Lead
日本機械学会論文集(B), Apr. 1998
Development of new mesh-free algorithm with a high accuracy for computational fluid dynamics
Lead
Trans. JSME, 1998
Application of Incomplete Discrete Wavelet Transform to a Poisson Equation Solver and Its Parallel ProcessingTANAKA Nobuatsu, Lead, This paper describes a powerful and simple new wavelet-based preconditioning method for the CG solvers of Poisson equation. The equation can be solved with an iterative matrix solver, however, in the absence of our method, the computing time will increase exponentially with respect to an increase in grid points. Use of our technique leads to a matrix with a bounded condition number so that computing time is reduced significantly. Results from our numerical experiments confirm the power and accuracy of our wavelet-based preconditioning method. Unlike many preconditioning methods which are not suitable for vector and parallel processing, our algorithm can take advantage of the extreme processing capabilities and enhance computing performance. For example, a speed up of over 100 fold can be achieved when solving Poisson equations on a Cray T3D using 128 processors in parallel., The Japan Society for Industrial and Applied Mathematics
Trans. of JSIAM, 1997
Incomplete discrete wavelet transform and its application to a Poisson equation solverN Tanaka; H Terasaka; T Shimizu; Y Takigawa, Lead, This paper introduces an incomplete discrete wavelet transform (iDWT), which is applied to a preconditioning method for linear equation systems discretized from differential equations. The linear systems can be solved with a matrix solver, but the convergence speed becomes worse with increase of condition number, which exponentially increases with the scale magnification. The use of wavelets in linear systems has an advantage in that a diagonal rescaling makes the number become bounded by a limited. value, and the advantage is utilized in a matrix solver presented by G. Beylkin. The method, however, has several problems and is difficult to apply to the real numerical analysis. To solve the problems, we introduce the iDWT method that approximates the discrete wavelet transform and is easy to implement in the computational analysis. The effects and advantages of the iDWT preconditioning are confirmed with one- and two-dimensional boundary value problems of elliptic equations. On Cray C94D vector computer, the iDWT preconditioned CG method can solve 2-D Poisson equation, discretized with 1,024x1,024 grid points, about 14 times faster than the ICCG method., TAYLOR & FRANCIS LTD
JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY, Jul. 1996,
[Reviewed] 小規模ブロック化行列の多項式を用いた共役勾配法の前処理手法の改良
田中伸厚; 寺坂晴夫, Lead
情報処理学論文集, Aug. 1995, [Reviewed]
小規模ブロック化行列の多項式を用いた共役勾配法の前処理手法の開発
田中伸厚; 寺坂春夫, Lead
情報処理学論文集, Apr. 1994, [Reviewed]
