Papers - Sawada, Tatsuo

Numerical Analysis of Nonlinear Water Waves Using Arbitrary Lagrangian-Eulerian Finite Element Method

Hiroshige Kikura, Tooru Takeguchi, Tatsuo Sawada and Takahiko Tanahashi

Transactions of the Japan Society of Mechanical Engineers, Ser.B (Japan Society of Mechanical Engineers)  57 ( 540 ) 2632-2639 1991.08

Research paper (scientific journal), Joint Work, Accepted

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Since free surface flows are seen in nature phenomena and artificial systems, the analysis for these flows has been more important in mechanical engineering. However, theoretical analyses are almost impossible because the boundary conditions are nonlinear equations in analyzing the free surface flows. Thus, numerical analyses are needed. Finite element method (FEM) which can be used for unstructured grid can easily treat boundary conditions. Thus, FEM is used in many technological fields. In this thesis, free surface flow problems were analyzed using the finite element method. In solving these problems, an arbitrary Lagrangian-Eulerian (ALE) kinematical description of the fluid domain was adopted, in which the nodal point can be displaced independently of the fluid motion. The ALE method was introduced into the Generalized Simplified Marker and Cell (GSMAC) method. Damping out the alternating errors was examined in this scheme.

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New transport system of a magnetic fluid by rotating magnetic fields

Hiroshige Kikura, Tatsuo Sawada andTakahiko Tanahashi

ASME FED-Vol.115, Liquid Metal Flows (ASME)     31-35 1991.06

Research paper (international conference proceedings), Joint Work, Accepted

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The magnetic fluid motion in a rotating magnetic field was examined at first. Influences of the magnetic field intensity, its frequency and the radius ratio of the concentric cylinders on flow patterns were investigated experimentally. According to these results, a new transport system of a magnetic fluid was presented. It consisted of the spiral tube wound around a circular cylinder. When the rotating magnetic field was applied, the height difference of fluid columns was observed, which corresponded to the pressure head between the entrance and exit of the tube. The pressure head was influenced by the magnetic field intensity, its frequency and diameter of the spiral tube. Effects of these parameters were discussed.

Natural convection of a magnetic fluid in concentric horizontal annuli

Tatsuo Sawada, Hiroshige Kikura, Atsushi Saito and Takahiko Tanahashi

Proceedings of the Second World Conference on Experimental Heat Transfer, Fluid Mechanics and Thermodynamics    1433-1440 1991.06

Research paper (international conference proceedings), Joint Work

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Natural convection of a magnetic fluid in concentric annuli was investigated experimentally. A thermosensitive liquid crystal was utilized for temperature visualization instead of flow visualization. When there was no magnetic field, developments of ordinary natural convection were observed. When a magnetic field was applied in the same direction of the gravity, wall-temperature distribution was observed as if an apparent gravity increased. But the clear influence of the magnetic field was not found. If a magnetic field was applied in the opposite direction of the gravity, the reverse natural convection was observed. Consequently, even if the intensity of the applied magnetic field was small, it played an important role in natural convection and heat transfer of a magnetic fluid. It was recognized that natural convection of a magnetic fluid could be controlled by the applied magnetic field.

磁性流体スロッシングにおける液面挙動と周波数応答

木倉宏成，澤田達男，棚橋隆彦

Transactions of the Japan Society of Mechanical Engineers, Ser.B (Japan Society of Mechanical Engineers)  57 ( 537 ) 1629-1634 1991.05

Research paper (scientific journal), Joint Work, Accepted

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矩形，円筒，球形容器に内に満たされた磁性流体のスロッシング現象に及ぼす磁場の影響を調べた。その結果，印加磁場の増加に伴って共振振動数が高周波数側に移行し，液面動揺も抑えられる事が明らかとなった。また，実験結果は理論解析結果ともよく一致し，理論解析の妥当性が確認できた。

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Numerical simulation of unsteady incompressible viscous flows by improved GSMAC-FEM

Yasumasa Kato, Toshihiro Sato, Tatsuo Sawada and Takahiko Tanahashi

Lecture Notes in Physics (Springer)  371   209-210 1990.12

Research paper (international conference proceedings), Joint Work,  ISSN  0075-8450

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A new FEM scheme using simultaneous relaxation of velocity and Bernoulli function is presented for unsteady incompressible viscous flow. This is an improved version of the GSMAC(Generalized Simplified Marker and Cell) FEM. To verify the scheme, transient 2-D Poiseuille flow and 3-D flow in a lid-driven cubic cavity are numerically calculated.

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Natural convection of a magnetic fluid under magnetic fields

Hiroshige Kikura, Tatsuo Sawada, Takahiko Tanahashi and Atsushi Saito

Proceedings of the Second KSME-JSME Fluids Engineering Conference (KSME, JSME)  2   128-133 1990.10

Research paper (conference, symposium, etc.), Joint Work

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容器内の磁性流体自然対流が印加磁場によって制御できる事を明らかにし、その熱伝達特性を調べた。

Propagation of surface waves of magnetic fluids in traveling magnetic fields

Hiroshige Kikura, Tatsuo Sawada andTakahiko Tanahashi

Journal of Magnetism and Magnetic Materials (Elsevier)  85 ( 1-3 ) 167-170 1990.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0304-8853

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Propagation of waves on the free surface of magnetic fluid is experimentally investigated. It is found that the surface velocity of the magnetic fluid depends on the intensity and frequency of traveling magnetic fields, and depth of the channel contained with the magnetic fluid. Theoretical investigation is also carried out in order to clarify the phenomena.

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GSMAC-FEM for incompressible viscous flow analysis (A modified GSMAC method)

Hideki Kawai, Yasumasa Katoh, Tatsuo Sawada and Takahiko Tanahashi

JSME International Journal, Ser.II (JSME)  33 ( 1 ) 17-25 1990.02

Research paper (scientific journal), Joint Work, Accepted

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The rotational form of the Navier-Stokes equations in which velocity and the Bernoulli function are variables is used in the GSMAC method. Velocity components and Bernoulli function are interpolated as a linear function and a constant function, respectively. This interpolation is simple and convenient for creating the mesh system. However, the approximation which is mentioned above makes it difficult to analyze inlet-outlet flows including the Neumann boundary conditions. The present paper shows a new modified GSMAC method which is applicable to high Reynolds flows with Neumann boundary condition (especially the pressure boundary). The modified scheme consists of an algorithm which satisfies the continuity equation much better than the previous GSMAC method.

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Flow of the entrance region in a porous pipe : flow with a change of radial wall velocity

Hideki Kawai, Tatsuo Sawada, Takahiko Tanahashi

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  55 ( 515 ) 1829-1835 1989.07

Research paper (scientific journal), Joint Work, Accepted

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A theoretical solution of a pulsatile flow in the entrance region of a porous pipe was derived by Oseen's approximation reported in the previous paper when the radial wall velocity was constant along the pipe axis. According to Hornbeck's investigation, radial wall velocity alters due to the difference between the inner and outer pressure of a porous pipe. In the present paper, we dealt with a pulsatile flow whose radial wall velocity varies exponentially along the pipe axis. Dynamic characteristics such as velocity, and pressure coefficient are precisely discussed on the boundary conditions for pulsatile injection and suction from the pipe wall.

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GSMAC-FEM for incompressible viscous flow analysis : A modified gsmac method

Hideki Kawai, Tatsuo Sawada, Takahiko Tanahashi

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  54 ( 507 ) 3118-3125 1988.11

Research paper (scientific journal), Joint Work, Accepted

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The GSMAC-FEM (Generalized Simplified Marker and Cell FEM) which is an extension of the SMAC-FDM is a stable and fast scheme for the incompressible viscous flow. The rotation form of the Navier-Stokes equation in which velocity and Bernoulli function are interpolated as a linear function and a constant function. This interpolation is simple and convenient in making the mesh system. On the contrary, the approximation which is mentioned above makes it difficult to analyze inlet-exit flow including the Neumann's boundary conditions. The present paper shows a modified GSMAC method which is available for high Reynolds flows with Neumann's boundary conditions (especially the pressure boundary).The modified scheme consists of an algorithm which satisfies the continuity equation much more than the previous GSMAC method.

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Numerical simulation of a blood flow in a stenosed tube

Hideki Kawai, Tatsuo Sawada and Takahiko Tanahashi

Role of Blood Flow in Atherogenesis (Springer)     131-137 1988.10

Research paper (international conference proceedings), Joint Work, Accepted

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A new finite element technique which is based on the multiplier method is presented to analyze incompressible flow problems. We apply this method to the flow analysis in a stenosed tube which is modeled by a cosine curve. Calculations are carried out for the flow whose Reynolds number is less than 1000. These results are compared with those obtained by a finite difference method. Separation and reattachment points agree with experimental results.

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Propagation of waves on the surface of a magnetic fluid by a traveling magnetic field

Tatsuo Sawada, Hiroshige Kikura and Takahiko Tanahashi

Proceedings of the 6th International Congress on Experimental Mechanics 1   264-269 1988.06

Research paper (international conference proceedings), Joint Work

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Propagation of waves on the surface of a magnetic fluid are investigated experimentally. It is found that the surface velocity of a magnetic fluid depends on intensity of a magnetic fie1d, frequency of a traveling magnetic field and depth of a magnetic fluid. Influences of these parameters on the propagation of waves are precisely examined. The surface velocity is proportional to intensity of a magnetic field. There exists the most suitable condition which gives the maximum surface velocity. This condition is closely connected with the frequency of a traveling magnetic field and the depth of a magnetic fluid. Theoretical investigation is also carried out in order to clarify the present phenomenon.

Numerical analysis of a flow in a stenosed tube

Hideki Kawai, Tatsuo Sawada and Takahiko Tanahashi

Physiological Fluid Dynamics 2   98-103 1987.08

Research paper (conference, symposium, etc.), Joint Work

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狭窄管内流れの数値解析を行い，狭窄の度合いによって，流線，等渦度線，狭窄部に作用するせん断応力がどのように変化するかを明らかにした。

Two-dimensional flow of magnetic fluid between two parallel plates

Tatsuo Sawada, Takahiko Tanahashi and Tsuneyo Ando

Journal of Magnetism and Magnetic Materials (Elsevier)  65 ( 2-3 ) 327-329 1987.03

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0304-8853

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Two-dimensional flows of magnetic fluid between two parallel plates in the transverse and longitudinal magnetic fields are investigated experimentally. The increasing rate of resistance coefficient is obtained and discussed with respect to the magnetic field length and Reynolds number.

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Unsteady forces on a body Immersed in a viscous fluid (3rd report: for an inclined thin elliptic cylinder)

Takahiko Tanahashi, Tatsuo Sawada, Eriya Kanai, Akira Chino and Tsuneyo Ando

Bulletin of JSME (JSME)  29 ( 257 ) 3717-3724 1986.11

Research paper (scientific journal), Joint Work, Accepted

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This paper considered a flow normal to an infinite thin elliptic cylinder which is uniformly accelerated from rest in a direction perpendicular to its generating lines in a viscous fluid. The Dufort-Frankel method for vorticity transport equation is used for the numerical simulation of viscous incompressible flows, and a new finite Fourier transform method is introduced in order to handle the stream function equation for accurate and efficient calculation. A major part of the present paper is devoted to physical properties of the flow during the early stages of wake developement behind an obstacle, for a Reynolds number of 98.11. A computer-aided flow visualization technique is used to demonstrate the main features of the hydrodynamic field for the flow. The rest of this paper demonstrates the important unsteady forces such as time-dependent drag, lift and moment acting on a body immersed in a viscous fluid, and presents specific numerical results for various transitions.

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Two-dimensional pneumatic wave propagation in pipes due to a step pressure input

Tatsuo Sawada, Takahiko Tanahashi and Tsuneyo Ando

Proceedings of the 5th International Conference on Pressure Surges    85-94 1986.09

Research paper (international conference proceedings), Joint Work, Accepted

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二次元流路内の圧力伝播の様子を特性曲線法を用いて数値解析を行い，速度分布，圧力分布の様子を明らかにした。

Dynamic characteristics of pneumatic transmission lines

Eriya Kanai, Tatsuo Sawada, Takahiko Tanahashi and Tsuneyo Ando

Fluid Control and Measurement 1   123-128 1986.08

Research paper (international conference proceedings), Joint Work, Accepted

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空気菅路内に圧力波が入射された場合の圧力波動のステップ応答について実験と理論解析を実施し，その特性を詳細に調べた。

A new finite element method for solving the unsteady Navier-Stokes equation

Eriya Kanai, Tatsuo Sawada, Takahiko Tanahashi and Tsuneyo Ando

Computational Mechanics '86, Proceedings of International Conference on Computational Mechanics 2   Ⅶ/97-Ⅶ102 1986.05

Research paper (international conference proceedings), Joint Work

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ナビエ・ストークス方程式を解くための新しい有限要素法を提案し，その有効性について報告した。

Unsteady forces on an inclined thin elliptic cylinder

Tatsuo Sawada, Takahiko Tanahashi, Eriya Kanai and Tsuneyo Ando

Computational Mechanics '86, Proceedings of International Conference on Computational Mechanics 2   Ⅶ/35-Ⅶ40 1986.05

Research paper (international conference proceedings), Joint Work

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扁平な傾斜だ円柱に作用する非定常流体力を差分法による解析によって求めた。レイノルズ数によって，それらがどのように変化するかを調べた。

Unsteady forces on a body immersed in a viscous fluid : 3rd Report, for an inclined thin elliptic cylinder

Takahiko Tanahashi, Tatsuo Sawada, Eriya Kanai, Akira Chino, Tsuneyo Ando

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  52 ( 475 ) 1197-1206 1986.03

Research paper (scientific journal), Joint Work, Accepted

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The flow normal to an infinite thin elliptic cylinder which is uniformly accelerated from rest in a direction perpendicular to its generating lines in a viscous fluid is considered. The Dufort-Frankel method for the vorticity transport equation is used for the numerical simulation of viscous incompressible flows, and a new finite Fourier transform method is introduced in order to handle the stream function equation for accurate and efficient calculation. A major part of the present paper is devoted to physical properties of the flow for the early stages of development of the wake behind the obstacle. A computer-aided flow visualization method is used to demonstrate the main features of the hydrodynamic field for the flow. The rest of this paper demonstrates the important unsteady forces such as time-dependent drag, lift and moment acting on the body immersed in a viscous fluid, and presents specific numerical results for various transition.

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