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Published: September 18, 2005
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Published: September 18, 2005
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Koji YAMANE, Takaaki KASUDA, Kiyoshi KAWASAKI
Article type: Article
Session ID: 101
Published: September 18, 2005
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This paper describes the generation of cavitation by pulsed water jetting and its capability for utilization. A submerged cavitating pulsed water jet was realized by a system that we developed. In this study, we visualized the cavitating water-jet in water-pool by laser-sheet imaging technique. And an experiment was carried out to evaluate the capability for surface processing of metal by impinging jet. From the experimental result, it was found that the present system have a capability for shot-peening of metal surface at longer stand-off distance.
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Kenichi TAKAGI, Naoki WATANABE, Nobuhisa MAKIGUCHI, Takafumi TATEISHI, ...
Article type: Article
Session ID: 102
Published: September 18, 2005
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Ships take in seawater as weight to keep its balance. This is called ballast water. Ballast water contains various microbe (planktons, fish eggs and bacteria, etc) in the sea. So discharge of ballast water gives bad influence on ecosystem of other sea area. This paper presents effect of destruction of planktons when cavitating jet impinges on target body. We researched what kind of target body and distance is more effective on destructing planktons. Target body shapes flat, U-notch, V-notch and horn-shaped target. Distance between nozzle and target body is 2mm, 4mm, 6mm, 8mm and 12mm. The experimental result showed that the horn-shaped target and the distance 8mm between nozzle and target body was most effective in destructing planktons. It was caused by the collapse of cavitation bubbles at the horn and shearing stress at the shoulder of target body.
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Akio SUZUKI, Masaki MISAWA
Article type: Article
Session ID: 103
Published: September 18, 2005
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Applying an optimal delay time reconstruction method and a point correlation dimension method to void fraction time series greatly improves the reliability of analysis. In this paper, required cross-sectional measuring points have been investigated.. We found 9-point averaging void fraction time series is sufficient for the analysis. One-point void fraction time series were also analyzed. When the air flow rate is low, all estimation results, except in the near area of a wall, passed the surrogate data test.
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Mitsuyoshi HIGASHINE, Kenji KATOH, Tsuneo AZUMA
Article type: Article
Session ID: 104
Published: September 18, 2005
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A theoretical study was conducted to investigate the critical condition at which the liquid droplet is sliding down on the inclined plate. The occurrence of sliding is dependent on the width of the droplets from the consideration of force balance in the tangential direction of the plate. The calculation of system free energy showed that the system is in equilibrium during the expansion of the droplet volume. Assuming that the attached surface of droplets to the plated is circular, the critical width was obtained from the condition that the system energy starts to increase. The critical volume was experimentally measured for some kinds of test liquids and plates. The results agree with those calculated from the theory in this study.
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Hiroyuki AKIMOTO, Souichi SAEKI, Takashi SAITO, Kazuyuki NAKAMURA, Ter ...
Article type: Article
Session ID: 105
Published: September 18, 2005
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This paper presents a novel temperature measurement method for microfluidic devices; "2-Color Laser-induced Fluorescence (2-Color LIF)". In general, a conventional method (1-Color LIF) strongly depends on the excitation intensity distribution which is generated by spatio-temporal intensity fluctuation of light itself and configuration of microchannel. In contrast, the proposed method can eliminate the undesirable influence using a ratio-metric technique with two fluorescence images, because fluorescence intensity can be approximately a linear function of the excitation light intensity. Therefore, it is possible to measure the temperature distribution quantitatively and simplify temperature calibration. As a result, spatial intensity error can be reduced to about 95% as compared with 1-Color LIF image. The temperature distribution in microchannel due to heat-diflusion was visualized wilh high resolution 0.24μm×0.24μm and sensitivity 1.48%/K.
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Keisuke Horiuchi, Prashanta Dutta
Article type: Article
Session ID: 106
Published: September 18, 2005
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Significance of Joule heating on combined electroosmotic and pressure driven flows inside a straight microchannel is estimated for isoflux channel wall condition. Temperature distribution is obtained in both thermally developing and fully developed region from analytic solution of steady state energy equation. The length of entrance regions is determined from the non-dimensional heat transfer characteristics. Our analytical solution matches with existing literature for slug, pressure driven, and pure electroosmotic flow cases. The thermal developing speed and heat transfer characteristics change with applied pressure gradient along the microchannel. The Nusselt number does not depend on the magnitude of Joule heating if and only if there is no pressure gradient in the flow.
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Kenta To, Makoto KIDERA, Hiroshi TSUKAMOTO, Koji MIYAZAKI
Article type: Article
Session ID: 107
Published: September 18, 2005
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A valve-less micropump was fabricated by an asymmetric Y-shaped channel and a diaphragm. The measured maximum total head rise and volumetric flow rate were 600 Pa at zero flow rate and 1.3ml/min at zero total head rise, respectively. The velocity distribution in the micropump was measured using particle image velocimeter (PIV) to investigate pumping mechanisms for the improvements of pump performance. The results show that the vortex generates near the branch when the working fluid is supplied. And the vortex was found to appear at the inlet of the asymmetric channel in pump mode. As the result of the present study, it was found that the vortexes work as the dynamic valves and play a key role for the micropump.
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Makoto KIDERA, Kenta TOH, Hiroshi TSUKAMOTO, Koji MIYAZAKI
Article type: Article
Session ID: 108
Published: September 18, 2005
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A valve-less micropump was fabricated by an asymmetric Y-shaped channel and a diaphragm. Numerical simulations are conducted to investigate the mechanisms of developed valve-less micro-pumps by using commercial software CFX-5. The numerical results show that the vortex generates near the diaphragm when the working fluid is supplied. And the vortex was found to appear at the inlet of the asymmetric channel in pump mode. As the result of the comparison between calculated and PIV measured velocity profiles, it was found that the vortexes work as the dynamic valves and play a key role for the micropump.
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Hirofumi Shintaku, Satoyuki Kawano, Takeo Kuwabara, Takaaki Suzuki, Is ...
Article type: Article
Session ID: 109
Published: September 18, 2005
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A novel cell encapsulation method in microchannel was studied. We used W/O emulsion in the rectangle microchannel fabricated by soft MEMS process. The cell encapsulation process and internal flow of the droplet were visualized. The velocity of the droplet and the cell were measured by the use of the digital image processing. Simple model for prediction of the all velocity was proposed. The theoretical result agreed well with the experimental data.
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Junta Sase, Tamio FUJIWARA, Hiroshi OHUE
Article type: Article
Session ID: 110
Published: September 18, 2005
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A new micro flow meter consisting of a capillary and pressure gauge has been developed. As the flow rate in the capillary obeys the Hagen-Poiseuille equation, the flow rate can be determined by measurement of the pressure difference between the entrance and exit of the capillary. An experimental study is performed to develop the measurement technique for a micro-scale pressure difference and the measurement error is discussed. The following results are derived from the experiments: When the flow rate changes suddenly as a step function, the pressure gauge output takes 10sec to follow the pressure difference change. In case of the flow meter using a capillary with 0.46mm diameter and 60mm length, the steady pressure difference gives the flow rate of 50 nl/s with an accuracy of ±3%. For the case of the flow rate over 50 nl/s, the measured pressure difference consists with the theoretical value with an accuracy of ±0.6%. On the other hand, the error between measured pressure difference and theoretical one becomes large for the flow rate under 50 nl/s.
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Yoshifumi OGAMI, Katsutoshi FUJINO, Ken NISHIKAWA
Article type: Article
Session ID: 111
Published: September 18, 2005
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Mixing performance of optical micro rotors with 3, 4 and 5 paddles has been studied by computational simulations. First, a relation between laser power and optical torque acting on the rotors is analyzed. Second, fluid torque which consists of pressure and sheer stress, and the mixing rate of two kinds of fluids are calculated by solving the three dimensional Navier-Stokes equations. It is found that the optical torque caused by the laser is proportional to the laser power and the torque increases with the paddle number, that the fluid torque is proportional to the rotation speed of the rotor and this torque also increases with the paddle number, and that 4-paddle rotor produces the most mixing rate for a fixed laser power among these three rotors.
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Hiroshi NAKAJIMA, Yasushiro NISHIOKA, Sohei MATSUMOTO, Koichi OZAKI, K ...
Article type: Article
Session ID: 112
Published: September 18, 2005
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The drag reduction of water flow on a finely meshed metal surface was experimentally investigated, in order to examine the effects of the air trapped on a hydrophobic surface with microstructures. A meshed stainless steel plate with circular holes (thickness: 50μm, hole diameter: 140μm, surface void fraction: 49%) was used as the bottom wall of a rectangular cross section test channel. The existence of the air in the mesh holes was controllable by filling a chamber beneath the plate with either air or water. The friction factor was measured in the turbulent regime (Reynolds number: 6000〜12000), for "dry" and "wet" states of the mesh surface. The results showed that a 25〜30% reduction of the friction factor compared to a smooth surface was obtained by the meshed surface with the air held in the mesh holes.
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Satoshi OGATA, Kensuke KANDA, Ming YANG
Article type: Article
Session ID: 113
Published: September 18, 2005
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The purpose of this study is to clarify the velocity profiles of dilute polymer solution near the wall surface by using an evanescent light source. Evanescent light emerges by total reflection of an incident laser and illuminates only particles that are very close to the wall surface. By changing the incident angle of the laser, the depth of the illuminated area of evanescent light can be changed. Test fluids were water and polyethylene-oxide (Peo15) solutions with 5 ppm. Fluorescent particles with the diameter of 100nm were dispersed in test fluids are used as tracer particles. The streamwise velocity profile in the direction of depth is measured with PTV system by changing the depth of the illuminated area. It was clarified that the velocity profiles of dilute polymer solution decreases significantly comparing that of water very close to the wall surface. It can be considered that the adsorbed polymer layers may be partially responsible for the decrease in velocity of polymer solution.
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Yukio KANEKO, Shunsuke WATANABE, Shu TAKAGI, Yoichiro MATSUMOTO
Article type: Article
Session ID: 114
Published: September 18, 2005
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Recently, industiral and medical applications which employ microbubbles have been the subject of much interest. Especially in the medical field, ultrasound imaging, sonodynamic therapy, gene therapy and heat coagulation of tumor are being investigated. In the field of bubble dynamics, it is known that bubbles play a role in converting the mechanical energy of an ultrasound wave into not only energy of acoustic emission but also heat energy deposition when they are subjected to an oscillating field. The kind of gas inside a bubble has a strong effect on the energy deposition from the bubbles. We conducted two types of experiments for the analysis of the thermal and acoustic properties of different types of gas bubble, and the relationship between the gas properties and radiation energies from bubbles are discussed. It is concluded that the balance between heat deposition and acoustic emission from the bubbles can be changed by changing the gas inside the bubbles.
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Hiroyuki TAKAHIRA, Takeshi NAGATA
Article type: Article
Session ID: 115
Published: September 18, 2005
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We investigate the influence of dynamic surface tension on the stability of trapped or attached microbubbles. Two kinds of equilibrium radii are observed for shrinking microbubbles. The first one is related to the equilibrium surface concentration of surfactant. The other is related to the decrease of the surface tension due to the compression of the surface area at the maximum surfactant concentration. The experimental results are compared with the numerical solutions by taking the influence of the dynamic surface tension on the gas diffusion into account. The simulations agree well with the experimental results.
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Minori SHIROTA, Masaharu KAMEDA
Article type: Article
Session ID: 116
Published: September 18, 2005
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Viscous drag effects on the translational motion of pulsating bubbles are studied experimentally. Not only the translation but the radial motion of a pair of bubbles are observed using high-speed photography. Experimental results for the translation are compared to the previous theoretical model derived by Takahira. This model takes into account the diffusion of vorticity from bubble surface, and is valid even for intermediate Reynolds number. Two asymptotic models, which are valid for both upper and lower Reynolds numbers, are also compared to clarify the viscous effects. It is revealed that the potential flow theory overestimates the viscous drag for bubbles having the maximum radial Reynolds number of 100. Moreover, the validity of Takahira's model is verified experimentally for bubbles having Reynolds number of O (10).
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Masahiro OTA, Makoto YOSHIDA, Kazunori WATANABE, Hiroshi OKANO
Article type: Article
Session ID: 117
Published: September 18, 2005
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Induced flow and motions of fine solid particles with irradiation of YAG laser beam in water droplet, often called laser trapping, are discussed in this paper. A micro-sized heat spot could be produced by the absorption of the laser beam, and heat transfer occurred from the heated glass plate to the water droplet with the particles. The local flow was induced by the effect of the heat transfer. These interesting phenomena were observed under microscope and recorded by a VHS connecting to a CCD camera. The particles were rotated with the irradiation of the laser beam, the revolution was too high compared to the VHS capture rate. The theoretical backgrounds on the induced flow and the motion of the fine particles are also discussed.
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Ryuta HATAKENAKA, Hiromi TOKURA, Shu TAKAGI, Yoichiro MATSUMOTO
Article type: Article
Session ID: 118
Published: September 18, 2005
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Deformation and motion of lipid bilayer vesicles with diameter of 10-50μm (giant vesicle, GV) in a simple-shear-flow have been observed by phase contrast microscopy. We develop a rotating-cylinder apparatus, which can create a simple-shear-flow with a steady shear rate. GVs prepared by the gentle hydration method are transferred to the apparatus and their behaviors in the flow were observed. In our observation, GVs are deformed to steady ellipsoidal shapes and show constant orientations with θ, which is the angle between the major axis and the flow direction. It is also observed that θ, becomes smaller with decrease of swelling ratio τ, which indicates the degree of deflation. Our experimental result shows the same tendency as the theoretical analysis does [Keller and Skalak, 1982, J. Fluid. Mech., 120, 27-47.].
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Kazunori YASUDA, Yuichi SUGIURA, Noriyasu MORI
Article type: Article
Session ID: 119
Published: September 18, 2005
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Velocity profiles of polymer solutions were directly measured in a microhannel with rectangular cross sections. The test fluids are 0.2 wt% aqueous solutions of polyacrylamide whose molecular weights are 6×10^6 (fluid A) and 1.5×10^7 (fluid B). The microchannel was made of PDMS and it is mounted on the glass plate. The velocity profile in the depth direction is discussed as a function of a shear rate. Consequently, for the flows of fluid A, a symmetric profile is observed in the region between the PDMS wall and the glass wall in a low flow rate, but the velocity profile slightly becomes asymmetric with increasing the shear rate: the velocity near the PDMS wall is larger than that near the glass wall. For the flows of fluid B, a slightly asymmetric profile is observed even in the low flow rate and a largely asymmetric one in the large shear rate. The PDMS wall significantly affects the velocity profile in the flow of polymer solution through a PDMS microchannel.
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Yuichiro IDE, Shinji TAMANO, Motoyuki ITOH, Kazuhiko YOKOTA
Article type: Article
Session ID: 120
Published: September 18, 2005
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This paper deals with flows of viscoelastic fluids such as aqueous polymer solutions, due to a rotating disc in a cylindrical casing. As the aqueous polymer solution, 0.1, 0.2, 0.5, 0.8 and 1.0 wt% polyacrylamide (PAA) solutions are used. The behavior of flow has been investigated using a flow visualization technique and a PIV measurement. The patterns of the secondary flow are classified using the Reynolds and elastic numbers. We found that a donut-type vortex or a spiral-type vortex was shed away from the rotating disc. In the region inside the spiral-type vortex, both tangential and radial velocity components were fluctuating periodically.
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Katusya NAGAYAMA, Akihiro IDOGAKI, Kazuhiro TANAKA
Article type: Article
Session ID: 121
Published: September 18, 2005
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The viscoelastic fluid shows various complex behaviors because they have both elasticity and viscosity. Fibers are often mixed with resin to increase strength of products in molding plastic. This flow phenomenon has not been clarified in detail. We study the viscoelastic flow phenomenon with fibers injecting to a channel. The visualized experimental results were compared with the numerical simulation results by the particle method.
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Kazuhiro HASEGAWA, Hiroshi MIZUNUMA
Article type: Article
Session ID: 122
Published: September 18, 2005
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The relationship between melt fracture and near wall instability was investigated at the die exit of capillary extrudate flow. The polymer was liner Polydimethylsiloxane. The flow at the die exit was observed for a diverging die, a long-straight die, and a short-straight die. In spiral fracture, polymer peeling appeared for the diverging die exit and the short-straight die exit. The long-straight die did not indicate the polymer peeling at the exit, but the particle-path visualization due to the dispersed micro spheres revealed a flow instability at the long-straight die exit.
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Takashi SATO, Tomiichi HASEGAWA, Takatsune NARUMI, Hiroshi WATANABE
Article type: Article
Session ID: 124
Published: September 18, 2005
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Reaction of jet issuing from small apertures has been measured by the jet-reaction method. We used one hole of 1.2mm and 0.5mm, porous membranes having numerous holes of 6.1μm, 4.9μm and 35μm, slots of 971μm, 131μm, 24μm and 18μm widths, and mesh screen composed of 49μm squares. Reynolds number ranges from 1 to 500. It is found that the jet of larger orifices and slots gives a reasonable agreement with the result of numerical analysis, but the jet from smaller size apertures gives the reaction lower than the data of the numerical analysis, especially zero for the 6.1μm hole. Some normal stress like the elastic stress of viscoelastic fluid is thought to be generated in micro-scale flows.
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Manabu KATO, Shinji NOBUHARA, Tsutomu TAKAHASHI
Article type: Article
Session ID: 125
Published: September 18, 2005
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In the purpose of development of new elongational rheometer to estimate planar elongational viscosity for various fluids, we investigated the way to generate planar elongational flow by using two-dimensional opposing flow. The relationship between elongation rate at the stagnation point and flow rate was measured from results of flow visualization. And elongational stress was evaluated from flow birefringence at the stagnation point by application of the stress-optic rule. From both results, planar elongational viscosity was estimated. The planar elongational viscosity compared with the results measured by using 4-roll mill flow cell and squeeze flow cell and they showed good agreement.
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Tsutomu TAKAHASHI, Daisuke SAKATA, Mayumi OUCHI, Masataka SHIRAKASHI
Article type: Article
Session ID: 126
Published: September 18, 2005
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Cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) in de-ionized water forms worm-like micelles at a certain concentration and shows remarkable viscoelastic property such as polymer solution. CTAB/NaSal aqueous solution causes flow induced structure change when both shear rate and strain are higher than a certain value in start-up behavior of Couette flow. Though the fluid is originally transparent, it turns out to be opaque in this state. In this report, the flow-induced structure in step-elongation behavior of squeezing flow was investigated. The occurrence condition of the planar elongation induced structure in the middle plane of the flow cell was measured concerning the solutions which have different concentration of NaSal. The relaxation time and the elastic modulus of one-mode Maxwell model were evaluated by dynamic viscoelastic test. The relationship between the critical planar elongation strain and Debora number based on the relaxation time is collapsed on a single curve independent of the molar concentration ratio of detergent and salt.
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Takamasa HASHIMOTO, Manabu KATO, Noriyasu MORI
Article type: Article
Session ID: 127
Published: September 18, 2005
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Worm-like micelles entangle and form networks like polymeric fluids. In the present study surfactant solutions system of CTAB/NaSal were used to examine the flow property and the flow-induced-structure of micellar network in pressure-driven flows through a slit channel. Flow property apparently exhibited the dependence on shear rate: Newtonian region, shear-thinning, shear-thickening, and shear rate jump. To investigate the micellar network structure flow birefringence and small angle light scattering were carried out. Birefringence became measurable at the beginning of shear-thinning region, and the absolute value of birefringence increased with increasing shear stress. Moreover, white turbidity caused by the change of the micellar network structure appeared before the shear-thickening region. In SALS measurement, the streak indicating that the alignment of micellar aggregates in the flow direction was observed.
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Mizue MUNEKATA, Kenichiro MATSUO, Hiroki TAWARA, Hideki OHBA
Article type: Article
Session ID: 128
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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Effects of non-Newtonian viscosity for surfactant solution on the vortex characteristics and drag-reducing rate in a swirling pipe flow are investigated by pressure drop measurements, velocity profile measurements and viscosity measurements. Non-Newtonian viscosity is represented by power-law model (τ=kD^n). Surfactant solution used has shear-thinning viscosity with n<1.0. The swirling flow in this study has decay of swirl and vortex-type change from Rankin's combined vortex to forced vortex. It is shown that the effect of shear-thinning viscosity on the decay of swirl intensity is different by vortex category and the critical swirl number with the vortex-type change is depend on shear-thinning viscosity.
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Takashi Koshiba, Noriyasu Mori
Article type: Article
Session ID: 129
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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In order to examine the effect of a converging-diverging flow for surfactant solutions in undulating slit channel, the measurement of pressure loss and light scattering were performed. The mixtures of CTAB and NaSal in distilled water were used as test fluids. In the measurement of pressure loss, it is found that the pressure loss in undulating channel becomes larger than that for the straight channel with a same width as undulating one. The excess pressure loss due to an effect of elongational flow occurs at about 1.0 s^<-1> of an apparent stretch rate and depends on the channel geometry. Furthermore, it is confirmed that the scattering pattern at the converging part was different from that at diverging one. These facts suggest that the micellar network structure is significantly affected by the stretch deformation.
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Kouske Nakahata, Hiroshi Mizunuma, Kunihiro Koshikawa
Article type: Article
Session ID: 130
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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The elongational flow and solidification of particle-dispersed photopolymers has been investigated. Capillary thinning and solidification were observed. It was found that solidification produced a wavy instability on the liquid bridge of photopolymer. Transient diameter profiles in elongation were compared with the prediction for Newtonian fluid. A new application related to the experimental results was discussed.
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Norihiro OHARA, Tomoyasu OKUMURA, Kunji CHIBA, Kazunori YASUDA, Noriya ...
Article type: Article
Session ID: 131
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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Velocity distribution of a steady pipe flow was measured using magnetic resonance imaging (MRI). Aqueous solutions of carboxymetyl cellulose (CMC) containing dispersed particle (e.g. glass flake, vinylon fiber, etc) were used as test fluids. The test fluids with high volume fraction of particles showed a plug-like velocity profile at high shear rates. The velocity profiles measured by MRI agreed well with those numerically calculated from the viscosity curves. In this research, to examine the effect of disperse particles on the flow field, rectangular channel with a contraction/expansion was also used.
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Satoru KIRYU, Takatsune NARUMI, Tomiichi HASEGAWA, Hiroshi WATANABE
Article type: Article
Session ID: 132
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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In this study, we have investigated the flow induced structure of liquid crystalline polymer solution in a flow through a two dimensional channel with a corner. The orientation angle and the dichroism were measured with a laser optical measurement system. The orientation angle had smoothly changed from the upstream of the corner to the downstream. A periodic oscillation in orientation angle was observed in the upstream flow, but it became smaller after the flow direction change. The dichroism also became a bit higher in the downstream region. In spite of no significant change in orientation angle and dichroism, a typical texture was obtained at the downstream region in polarized observation.
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Yuji Murata, Tetsuhiro Tsukiji
Article type: Article
Session ID: 133
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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Flow visualization of a liquid crystal mixture in mini cylinders is conducted under application of the rotating electric fields. The mini cylinder with the electrode strips on some parts of the inner surface of the cylinder is used. The cylinder is 2.0mm in length and 1.1mm in diameter. The three-phase alternating currents are used as the rotating electric fields. The frequency or the amplitude of the voltages is changed to investigate the effect of the unsteady electric fields on the flow phenomenon of the liquid crystal mixture. When the frequency and the voltage of the three-phase voltages are 60Hz and 255V the rotation speed of the liquid crystal is 26.0 r.p.m.
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Takanori MATSUMI, Kensaku ISHIMARU, Tomohiro TSUJI, Shigeomi CHONO
Article type: Article
Session ID: 134
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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As a fundamental study of developing liquid crystalline actuators by using back-flow, velocity distributions of a nematic liquid crystal under electric fields were measured. We prepared for two kinds of liquid crystal cells whose twist angles were 0 and 180 deg, and the gap of them was 50μm. We selected 5CB liquid crystal as a nematic liquid crystal. The velocity distributions were visualized using polystyrene particles with 2.5μm in diameter. The movement of small particles was observed by using a polarizing microscope. When the twist angle was 0 deg, the velocity distribution was antisymmetric with respect to the center plane of the cell. When the twist angle was 180 deg, on the other hand, the velocity distribution showed positive values at every point, and the maximum value was obtained at the center position of the cell. As a result, it is found that the twist angle has large effect on the distribution of the velocity and that the maximum absolute value for the twist angle of 180 deg is larger than that for the twist angle of 0 deg.
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Chunbo Liu, Tomohiro TSUJI, Shigeomi CHONO
Article type: Article
Session ID: 135
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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Simulation of velocity profiles of electric-fields induced nematic liquid crystalline flows between parallel plates has been achieved using the Leslie-Ericksen theory, as the fundamental research on the development of liquid crystalline micro-actuators. When the twist anchoring angle, which is the twist angle difference between the plates, is 0 degree, the induced velocity profile is anti-symmetric S-shaped profile. Thus the total flow rate of the system remains zero. On the other hand, the velocity profile is symmetric in x-direction and anti-symmetric in z-direction, for the case that the twist angle is 180 degree. The results show that the induced flow can be controlled by changing the anchoring conditions.
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Naoki SASAKI, Takatsune NARUMI, Tomiichi HASEGAWA
Article type: Article
Session ID: 136
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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We have examined a new method of flow rate evaluation from the optical pattern of liquid crystal flow in a minute ER channel. The two-dimensional channel consists of two ITO glass electrodes, and two cases with a stripe-patterned electrode and no patterned one were tested in the low flow rate condition. A tail shaped patterns were observed in the just downstream of the pattern and the length of the tail has a good correlation with the flow rate. Moreover, the average brightness obtained with no patterned electrode was also helpful for the flow rate evaluation.
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Kunio SHIMADA
Article type: Article
Session ID: 137
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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As a new intelligent or smart fluid, we have proposed an amorphous compound fluid (ACF). This fluid has nm-sized magnetite and μm-sized amorphous particles in a solvent. In this report, we apply the ACF to a float polishing. And it shows the polishing results. It is clarified that the polishing effect is better utilizing ACF than MCF under a polishing condition of small clearance between the polishing and polished surfaces. The cause is due to the formation of string- and network-like clusters of ACF occurred by the remanent magnetization of the amorphous particles.
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Shigeyuki URANO, Yuki MIYAMOTO, Takayuki SAITO
Article type: Article
Session ID: 138
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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Wall-bubble interaction is one of the most important subjects for a deep understanding of gas-liquid two-phase flows. This study focuses on the liquid motion at the wall-bubble collision as well as the bubble motion. The liquid motion induced by the collision was measured via PIV. The motion of the bubble was microscopically visualized via a high-speed video camera, in order to clarify the motion of the center of gravity and the surface shape deformation. As a result, it was confirmed that (1) the bubble was forced by the wall in the area of L_<ap>/D_<eq>≒0.5, (2) after the collision, the bubble velocity was reduced, and the shape of bubble come to spherical, (3) the vorticity plays important role for the bubble motion.
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Shingo UCHIDA, Kazuto ISHIDA, Shuichi IWATA, Hideki MORI, Tsutomu ARAG ...
Article type: Article
Session ID: 139
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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An enhancement of removing bubbles from shear-thinning fluids was studied. We have found that periodical pressure changes in the shear thinning fluids have a good effect on enhancing bubbles rising, where local shear flows occur in the vicinity of bubbles due to a change in volumes of bubbles, and then local apparent viscosities of the surrounding liquids are lowered, therefore drag forces are reduced. The pressure inside a closed test cell was controlled by vibrating a thin-film set on the cell. We observed that the bubble rising velocities with periodical pressure changes were faster over 200 times in some case than its natural bubble rising velocity.
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Takumi KATSUMATA, Masaharu KAMEDA
Article type: Article
Session ID: 140
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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Deformation of a gas bubble in a highly viscous pipe flow was investigated experimentally. The pipe flow is generated in a vertical transparent tube by the pressure difference between both ends of the tube. The deformation was recorded by high-speed photography. The velocity field of liquid flow was measured by Particle Image Velocimetry-Laser Induced Fluorescence (PIV-LIF). Two materials, polysaccharide (Hayashibara Pullulan) water mixture and silicone oil (Shin-etsu KF96H) were used as the test liquids. The steady bubble shapes and orientations were correlated with the capillary number Ca. The experimental data were compared with a theoretical prediction in a simple shear flow. The small deformation is predicted well with the theory for the simple shear. At higher capillary number, the deformation is different from that in a simple shear flow, because the nonuniformity of shear rate in the pipe is a substantial effect on the bubble shape.
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Satoshi URAKAWA, Yasuhiro MIZUNO, Takayuki SAITO
Article type: Article
Session ID: 141
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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In order to solve global warming it is essential to realize highly efficient systems such as chemical plants or power plants including multiphase systems. In these systems, probe methods are useful for real-time and high accuracy measurements. In this study, the authors measured bubbles properties via Single-Tip Optical-fiber Probe (S-TOP). The gradient of signals obtained from the S-TOP is proportional to the interfacial velocity. We applied this relationship to bubble measurement. As a result, it is showed that the measurement for ellipsoidal shape bubble has high accuracy; the errors were less than 2%.
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Kazunori SORIMACHI, Tomiichi HASEGAWA, Takatsune NARUMI
Article type: Article
Session ID: 142
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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When air pushes a more viscous fluid in two parallel plates by a syringe pump, viscous fingering pattern have been observed. Water and aqueous glycerin solutions are used as Newtonian fluids, and aqueous glycerin solutions adding polyacrylamide (Separan AP30) are used as non-Newtonian fluids. It was found that it showed the bifurcation of viscous fingering to be different by a kind of solution. It was found that the solution concentration, gap and air pressure influenced a bifurcation pattern. Furthermore, viscosity and air pressure influenced tip speed of bifurcation in Newton fluid.
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Hiroshi Mizunuma, Kenji Shimokasa, Koutarou Tsuchiya, Hiro Ogoshi, Nir ...
Article type: Article
Session ID: 143
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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The swallowing flow was simulated to evaluate the safe care foods for the swallowing disorders. As the rheological model, a three-elements Maxwell model was applied to the jelly bolus, and the elastic model was applied to each part from mouth to esophagus. The friction between the bolus and the mucous surface was expressed using a static and a dynamic frictional coefficient. The simulated results approximately agreed with the results of the video fluolography.
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Yoshihiro MINO, Hiroshi MIZUNUMA, Kenji SHIMOKASA, Atsushi Senoo, Hiro ...
Article type: Article
Session ID: 144
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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Three-dimensional bolus geometry was recognized from multi-angle 2D X-ray image of video fluolography. The developed method enabled free view angle for the flowing bolus. A mesh model was created from the digitized bolus shape, and was used for FEM analysis. The obtained swallowing pressure approximately agreed with the past result.
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Tomoo ISHIKAWA, Tamio FUJIWARA, Hiroshi OHUE
Article type: Article
Session ID: 201
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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In order to investigate the relation between a flow structure and a sphere behavior in a diverging funnel, an observation of the sphere behavior and flow visualization in the diverging runnel by the laser light sheet method were carried out. The sphere behavior could be classified into two categories i.e., pattern (a): the sphere lifts toward the flow direction with a rotation, and pattern (b): the sphere lifts with a rotation also a revolution along the cannel wall. The sphere lift distance decreases as the funnel angle increases and the sphere weight gains. The time delay, which the cease of the sphere motion takes since the mainstream stops, depends on the kinetic energy of the sphere, the gravity of the sphere and the resistance force acting on the sphere that are increase as the sphere size increases, respectively.
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Masamichi NAKAGAWA, Takashi YABE, Masaya MISAKI, Kazuto MANOME, Tetsur ...
Article type: Article
Session ID: 202
Published: September 18, 2005
Released on J-STAGE: August 01, 2017
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A golf ball is pitted with about 300-500 of dimples on the surface, and their effects of boundary layer control to lengthen the range greatly are well-known. The present paper reports the experimental data measured using a wind tunnel concerning the effect of drag reduction of dimpled spheres in back-spin and the effect of lift production as the synagetic of both dimples and back-spin. We obtained the aerodynamic feature of dimpled spheres in back-spin that the inclinations of drag polars change counterclockwise with a decrease in the depth of dimples. We also found first that the efficiency of lift production is approximately 35% within the limits of our experiments.
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