Papers - Sawada, Tatsuo

Distorted pressure histories due to the step responses in a linear tapered pipe (6th report, for arbitrary cross-sections)

Takahiko Tanahashi, Tatsuo Sawada, Kazuyuki Shizawa and Tsuneyo Ando

Bulletin of JSME (JSME)  29 ( 249 ) 795-801 1986.03

Research paper (scientific journal), Joint Work, Accepted

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This paper describes one such development. A new method of solving a one-dimensional wave equation in linear tapered compound pipes with arbitrary cross-sections has been devised. Results obtained by this theory are compared with experiments in pipes with square cross-sections. And we obtained the following conclusions: (1) Damping coefficients in an arbitrary cross-section are defined and are expressed analytically for some representative cross-sections. (2) The viscous solution of a wave equation obtained by Laplace transform explains well distorted pressure histories in a linear tapered pipe with an arbitrary cross-section. (3) Pressure waves in a square cross-section include higher modes of frequency and damp more rapidly than those in a circular cross-section. but fundamental characteristics as waves are independent of the cross-section of the pipe except for the small aspect ratio.

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Oscillatory flow of a micropolar fluid in a circular tube

Tatsuo Sawada, Takahiko Tanahashi and Tsuneyo Ando

Physiological Fluid Dynamics 1   91-96 1985.12

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

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円管内の極性流体の振動流を解析し，血液流の実験結果との比較検討を行った。

Unsteady forces acting on a body immersed in viscous fluids (2nd report, uniformly accelerated flat plate, elliptic cylinder and circular cylinder)

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

Bulletin of JSME (JSME)  28 ( 242 ) 1634-1641 1985.08

Research paper (scientific journal), Joint Work, Accepted

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The initial stage of flows due to uniformly accelerated flat plate, elliptic and circular cylinders from rest in incompressible viscous fluids are numerically studied by the finite difference method. The time dependence of stream lines and equi-vorticity lines are shown in flow patterns. The Dufort-Frankel technique is used for solving the vorticity transport equation and the finite Fourier tranform for solving the stream function, which is applied to the analysis of a block tridiagonal matrix equation. The main conclusions are as follows; (1) The Fourier series method is more than ten times faster than the SOR method. (2) Numerical experiments here are in very good agreement with real experiments on a flat plate and a circular cylinder. (3) The length of vortex pairs behind a uniformly accelerated elliptic cylinder at the angle of attack 90° is obtained as a resultant of numerical experiments. (4) The growing process of the secondary vortices behind a circular cylinder is revealed at Reynolds number 731.

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Distorted pressure histories due to the step responses in a linear taperd pipe : 6th Report, for arbitrary cross-sections

Takahiko Tanahashi, Tatsuo Sawada, Kazuyuki Shizawa, Tsuneyo Ando

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  51 ( 467 ) 2313-2320 1985.07

Research paper (scientific journal), Joint Work, Accepted

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Although much progress has already been made in solving problems in step responses of pressure in a linear tapered pipe, new developments are still needed before the two dimensional wave equation can be solved routinely. This paper describes one such development. A new method of solving one dimensional wave equation in linear tapered compound pipes with arbitrary cross-sections has been devised. Results which are obtained from this theory are compared with experiments in pipes with square cross-sections. And we obtained the following conclusions: (1) Damping coefficients in an arbitrary cross-section are defined and are expressed analytically for some representative cross-sections. (2) The viscous solution of wave equation obtained by Laplace transformation explains well distorted pressure histories in a linear tapered pipe with an arbitrary cross-section. (3) Pressure waves in a square cross-section include higher modes of frequency and damp rapidly more than ones in a circular cross-section. But fundamental characteristics as waves are independent of the cross-section of the pipe except for the small aspect ratio.

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Unsteady forces on a boody immersed in viscous fluids : 2nd Report, uniformly accelerated flat plate, elliptic and circular cylinders

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)  50 ( 460 ) 3142-3151 1984.12

Research paper (scientific journal), Joint Work, Accepted

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The early stage of the flows due to uniformly accelerated flat plate, elliptic and circular cylinders from rest in incompressible viscous fluids are numerically studied by the finite difference method. The time dependence of streamlines and equi-vorticity lines are shown in the flow patterns. The Dufort-Frankel technique is used for solving the vorticity transport equation and the finite Fourier transport equation and the finite Fourier transform for solving the stream function, which is applied to the analysis of a block tridiagonal matrix equation. The main conclusions are as follows ; (1) The Fourier series method is more than ten times faster than the SOR method. (2) Numerical experiments obtained here have very good agreements with real experiments for flat plates and circular cylinders. (3) The length of vortex pairs behind an uniformly accelerated elliptic cylinder at the attack angle 90° is obtained as a resultant of numerical experiments. (4) The growing process of the secondary vortexes behind a circular cylinder is revealed at Reynolds number 731.

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Unsteady forces on a body immersed in viscous fluids (1st report: for a uniformly accelerated elliptic cylinder)

Takahiko Tanahashi, Tatsuo Sawada, Akira Chino, Shinji Kawamoto and Tsuneyo Ando

Bulletin of JSME (JSME)  27 ( 230 ) 1598-1606 1984.08

Research paper (scientific journal), Joint Work, Accepted

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A new numerical method for obtaining the forces on a body immersed in viscous fluids is derived for a uniformly accelerated elliptic cylinder from rest. In an analytical study, Fourier series expansion and boundary layer variable expansion are used because of good convergence and accuracy at high Reynolds numbers. An application of discrete Fourier transform to a block tridiagonal matrix leads to a high speed calculation over ten times as fast as the SOR method. From this analysis, the coefficients of drag, lift and moment exerted on a unit spanlength are obtained, and they consist of two components due to pressure and viscous force. Distribution of vorticities on the surface, which is important for the characteristics of heat conduction, is reveal ed in detail. Furthermore, the authors confirm that the separation time shown by Blasius at the trailing edge has a larger error when the eccentricity of the elliptic cylinder goes to unity.

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Response of magnetic fluids in annular pipes under the influence of external magnetic fields

Takahiko Tanahashi, Tatsuo Sawada, Kazuyuki Shizawa and Tsuneyo Ando

Bulletin of JSME (JSME)  27 ( 229 ) 1431-1437 1984.07

Research paper (scientific journal), Joint Work, Accepted

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A phenomenological treatment is given for steady magnetic fluid flows in annular pipes in the presence of uniform external magnetic fields. It is found that the apparent viscosity of a dilute colloidal suspension of ferromagnetic particles is a marked function of both the magnitude and direction of an externally applied magnetic field. The experimental fact shown by McTague(1969) that the additional viscosity is greater by a factor of 2 for the field parallel to the flow than for the field perpendicular to the flow is theoretically explained. Analytical expressions are derived for the distributions of velocities and angular velocities of the magnetic fluid in annular pipes under the influence of the external field. The induced magnetization calculated here to the first order is skewsymmetric with respect to the plane through the center line of the pipe and perpendicular to the applied magnetic field.

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The forces on a body in an unsteady viscous fluid : 1st Report, for an uniformly accelerated elliptic cylinder

Takahiko Tanahashi, Akira Chino, Shinji Kawamoto, Tatsuo Sawada, Tsuneyo Ando

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  49 ( 448 ) 2677-2684 1983.12

Research paper (scientific journal), Joint Work, Accepted

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だ円柱が突然加速運動を開始した場合のだ円柱まわりの流れ場を差分法によって数値解析し，だ円柱の抗力係数，揚力係数が時間経過と共にどのように変化するかを調べた。

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Response of ferrofluids in annular pipes under the influence of external magnetic fields

Takahiko Tanahashi, Tatsuo Sawada, Kazuyuki Shizawa, Tsuneyo Ando

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  49 ( 447 ) 2513-2521 1983.11

Research paper (scientific journal), Joint Work, Accepted

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A phenomenological treatment is given for the steady ferrofluid flows in annular pipes in the presence of uniform external magnetic fields. It is found that the apparent viscosity of a dilute colloidal suspension of ferromagnetic particles is a marked function of both the magnitude and direction of an externally applied magnetic field. The experimental fact shown by McTague (1969) that the additional viscosity is greater by a factor of 2 for the field parallel to the flow than with it perpendicular is theoretically explained. Analytical expressions of the distributions of velocity and angular velocity of the ferrofluid in annular pipes are derived under the influence of the external field. The induced magnetization calculated here to first order is skewsymmetric with respect to the plane through the center line of the pipe and perpendicular to the applied magnetic field.

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Stokesian flow of a micropolar fluid past a sphere

Tatsuo Sawada, Toshihiro Kamata, Takahiko Tanahashi and Tsuneyo Ando

Keio Science and Technology Reports (Keio University)  36 ( 4 ) 33-47 1983.09

Research paper (bulletin of university, research institution), Joint Work, Accepted

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極性流体の球まわりのStokes流を理論解析した。各種パラメータが流線，等渦度線に及ぼす影響を調べた。

A note on the analytical treatment in ferrohydrodynamics

Takahiko Tanahashi, Tatsuo Sawada, Tsuneyo Ando, Motoichi Iga and Hiroyuki Torii

Bulletin of JSME (JSME)  26 ( 219 ) 1509-1517 1983.09

Research paper (scientific journal), Joint Work, Accepted

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A new complete set of basic equations for magnetic suspensions is derived on the theory of micropolar fluids developed by Eringen and a solution to these basic equations is obtained analytically for a steady motion of magnetic suspensions in a circular pipe which is placed in a homogeneous magnetic field parallel to the flow direction. A phenomenological treatment is given for the specification of material constants of a micropolar fluid, which are vortex viscosity and spin viscosity. In order to clarify the dynamical flow characteristics in the presence of a magnetic field, six dimensionless parameters to show the magnetic effect, polar effect, wall surface effect and so on are introduced into the solution for the rotational Peclet number. Some discussions are presented on velocity profiles, distribution of microrotations and distribution of vorticities. In particular, the suspension is non-Newtonian even if a magnetic field does not exist.

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A note on the analytical treatment in ferrohydrodynamics

Takahiko Tanahashi, Tatsuo Sawada, Tsuneyo Ando, Motoichi Iga and Hiroyuki Torii

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  49 ( 437 ) 53-61 1983.01

Research paper (scientific journal), Joint Work, Accepted

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磁性流体の構成方程式を新たに提案し，それを円管内の流れ場解析に用いた。そして，従来明確で無かった流れ場の様子を明らかにした。

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Distorted pressure histories due to the step responses in a linear tapered pipe (5th report, case of a tank being installed at the end)

Takahiko Tanahashi, Yutaka Yamashita, Tatsuo Sawada and Tsuneyo Ando

Bulletin of JSME (JSME)  25 ( 208 ) 1521-1528 1982.10

Research paper (scientific journal), Joint Work, Accepted

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Distorted pressure histories in a linear tapered tube equipped with a tank at the end are experimentally investigated by the step pressure input. And also this problem is theoretically solved by two methods, i.e., eigenfunction expansion and asymptotic expansion. The peak pressure in the tube can be controlled by the capacity of the tank. Large capacity leads to an open end situation. The height of the pressure wave is proportional to the inverse of the tube radius. A one dimensional wave equation including the viscous term in the equation of motion and the effect of the variable cross section is simplified by special transformation, and the simplified equation is solved by the method of the Laplace transform. The resultant analytical solution has a clearer representation than Schuder-Binder's solution.

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Oscillatory flow of a micropolar fluid as a model for blood flow

Tatsuo Sawada, Takahiko Tanahashi and Tsuneyo Ando

Keio Science and Technology Reports (Keio University)  35 ( 6 ) 105-121 1982.07

Research paper (bulletin of university, research institution), Joint Work, Accepted

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血液流のモデルとして極性流体の円管内流れを取り上げ，血液の流動解析への適用性について検討し，ヘマトクリットを変化させた場合の実験結果との比較検討を行った。

Flow of the entrance region in a porous pipe (3rd report: transient flow)

Takahiko Tanahashi, Hideki Kawai, JunMasuzawa, Tatsuo Sawada and Tsuneyo Ando

Bulletin of JSME (JSME)  25 ( 205 ) 1070-1078 1982.07

Research paper (scientific journal), Joint Work, Accepted

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This study deals with a transient laminar flow, which is started from rest, in the entrance region of a porous pipe. This flow analysis is applied to transpiration cooling systems and research equipment for production of tidal current. In this report, the problem is analyzed by a modified momentum integral method using the integral form of the equations of continuity, momentum and energy. The following conclusions were obtained ; (1) Dynamic distributions of velocity profiles, wall frictions and pressures are obtained numerically. (2) The relation between the flow rate of injection or suction and inlet length of the entrance region is made clear. (3) Each dynamic state in the pipe is found with changeable inlet velocities and with variable sections or injections. (4) It is confirmed that the modified momentum integral method is valid for the slip velocity on the porous wall which makes the inlet length short.

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極性流体の二重円管内の軸方向定常流れ

澤田達男，棚橋隆彦，安藤常世

日本機械学会論文集(Ｂ編) (日本機械学会)  48 ( 427 ) 576-580 1982.03

Research paper (scientific journal), Joint Work, Accepted

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二重円管内の極性流体の軸方向定常流れを理論解析し，その流動特性を明らかにした。

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Distorted pressure histories due to the step responses in a linear tapered pipe (5th Report, case of a tank being installed at the end)

Takahiko Tanahashi, Yutaka Yamashita, Tatsuo Sawada and Tsuneyo Ando

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  48 ( 426 ) 220-228 1982.02

Research paper (scientific journal), Joint Work, Accepted

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末端に圧力タンクが設置された直線テーパ管内の圧力波動の伝播の様子を実験を行って明らかにし，理論解析結果と比較検討し，理論解析の有効性を明らかにした。

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Oscillatory flow of a fluid with couple stress

Tatsuo Sawada, Takahiko Tanahashi and Tsuneyo Ando

Keio Science and Technology Reports (Keio University)  34 ( 4 ) 65-82 1981.12

Research paper (bulletin of university, research institution), Joint Work, Accepted

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偶応力を持つ流体として極性流体を取り上げ，その管内振動流を解析し，偶応力の流れ場に及ぼす影響を調べた。

Flow of the entrance region in a porous pipe (3rd Report: transient flow)

Takahiko Tanahashi, Hideki Kawai, JunMasuzawa, Tatsuo Sawada and Tsuneyo Ando

Transactions of the Japan Society of Mechanical Engineers Series B (Japan Society of Mechanical Engineers)  47 ( 423 ) 2131-2138 1981.11

Research paper (scientific journal), Joint Work, Accepted

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多孔質円管内の助走区間領域における過渡流れを理論的に調べ，しみ出し・しみ込み速度が速度分布の発達過程に及ぼす影響を明らかにした。

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Fundamental steady flow of polar fluids

Tatsuo Sawada and Takahiko Tanahashi

Bulletin of JSME (JSME)  24 ( 196 ) 1778-1786 1981.10

Research paper (scientific journal), Joint Work, Accepted

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A few fundamental steady flows of polar fluid, i.e., flow in a circular tube, flow between two parallel plates and flow between two coaxial cylinders are analyzed with the help of the theory of Eringen. Couple stress and spin angular momentum are considered in this approach. The exact solutions for velocity, micro-rotation, vorticity and shearing stress are obtained mathematically. These solutions are characterized by two parameters, i.e., the ratio of viscosities ε and the size effect parameter λ which do not appear in a Newtonian fluid. ε is the ratio of vortex visoosity to shear viscosity. λ means the size relation between the corpuscle and the characteristic length. The solutions are compared with those of Newtonian fluid and it is investigated how they vary with ε and λ. Apparent viscosity is determined for each flow. Material constants of polar fluid can be decided from these apparent viscosities.

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