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Published: September 07, 2007
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Article type: Appendix
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Article type: Index
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A1-A6
Published: September 07, 2007
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Kazunori SORIMACHI, Tomiichi HASEGAWA, Takatsune NARUMI
Article type: Article
Session ID: 1401
Published: September 07, 2007
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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. Aqueous solutions of CTAB(Hexadecyletrimethylammonium Bromide) with NaSal as salt 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. And, it was found that the solution concentration, salt concentration, gap and air pressure influenced a bifurcation pattern. Furthermore, it was found a complicated bifurcation pattern in surfactant solution with higher salt concentration. Then, tip speed of bifurcation was high.
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Koki MORI, Takehiro YAMAMOTO
Article type: Article
Session ID: 1402
Published: September 07, 2007
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Worm-like micelles entangle and form networks like polymeric fluids. In the present study surfactant solution systems of CTAB/NaSal were used to examine the flow property with a strain-controlled parallel-plate rheometer and to carry out birefringence measurements of surfactant solutions. At relatively low salt concentrations, transient birefringence after step changes in shear rate exhibited large overshoot at high shear rates and the convergent value of birefringence is relatively small. On the other hand, at relatively high salt concentrations, transient birefringence after step changes in shear rate exhibited small overshoot at high shear rates and the convergent value of birefringence is relatively large. Thus, the occurrence of the birefringence overshoot in the step-rate response is related to the salt concentration.
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Tsutomu TAKAHASHI, Hiromi MORIKAWA, Mayumi OUCHI, Masataka SHIRAKASHI
Article type: Article
Session ID: 1403
Published: September 07, 2007
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Flow-induced structure change of a surfactant solution caused by sinusoidal shear flow was investigated. An aqueous solution of CTAB/NaSal is used as a test fluid and it is known that this surfactant makes wormlike micelles and it causes flow-induced structure change in step shear. In this experiment, it is found that the sinusoidal shear strain also causes shear-induced structure change and the appearance condition of critical shear strain and shear rate is almost the same measured by step shear. The maximum shear stress at the first period is very high and it decreases at the following period. The relaxation time of this reducing maximum shear stress was evaluated and it is found that it is decreasing with increasing angular frequency and with increasing the maximum strain.
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Takashi Koshiba, Takehiro Yamamoto
Article type: Article
Session ID: 1404
Published: September 07, 2007
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We measured the steady shear viscosity for surfactant solutions with a rheometer of cone-plate type and observed a liquid surface at the circumference of cone to examine the variation of shear-thinning property with increasing a shear rate. Test fluids used in this experiment were the mixture of CTAB and NaSal in distilled water. In the measurement of shear viscosity, the shear-thinning property was confirmed at a lower shear rate than 5.0s^<-1> for all fluids. However, beyond a shear rate of 5.0s^<-1>, the decrement of shear viscosity due to shear-thinning property became gentle. Such property of shear viscosity was closely connected to the transition of micellar network structure for surfactant solutions. Furthermore, it is found that the liquid surface at the circumference of cone for the higher shear rate becomes unstable and the flow instability is appeared in the gap of cone and plate.
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Yukiharu IWAMOTO, Hideki HIBARA, Motosuke SOGO, Koichi MURAKAMI, Hirom ...
Article type: Article
Session ID: 1405
Published: September 07, 2007
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Flow characteristics of surfactant solution flowing in a curved circular pipe were investigated experimentally by means of pressure measurement and laser doppler anemometry. The curvature radius of the present pipe is twice as the same as its diameter (2×85.1mm), and Reynolds number and the concentration of the solution investigated in LDV measurement were 60000 and 100ppm, respectively. It was found that the region that has larger velocity deviated inner at the inlet of the curved part, and outer at the exit, compared with the water. It was also found that the secondary flow became stronger, and flow mixing between large and small velocities did not occur much till the velocity shear rate reaches to its of shear-thinning.
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Hiroki OKADA, Mamoru TANAHASHI, Toshio MIYAUCHI
Article type: Article
Session ID: 1406
Published: September 07, 2007
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The characteristics of heat transfer and drag reduction of turbulent water flow with surfactant have been investigated based on the coherent fine scale eddy in near-wall turbulence. To analyze the heat transfer and drag reduction, time scale ratio of surfactant to coherent fine scale eddy has been introduced. This time scale ratio characterizes the range of drag and heat transfer reduction, simultaneously. With the modification of time scale of the coherent fine scale eddy, the range of the drag reduction for heat exchanging cases agree with those for no heat exchanging cases.
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Takanori MATSUMI, Tomohiro TSUJI, Shigeomi CHONO, Yoshitaka MIEDA
Article type: Article
Session ID: 1407
Published: September 07, 2007
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Tetsuhiro TSUKIJI, Hiroki SATO, Kenta SUZUKI
Article type: Article
Session ID: 1408
Published: September 07, 2007
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It is confirmed that the rotation flow of liquid crystals in the cylinder electrode can be obtained by applying three-phase alternating current at first. In the present study, a pump based on the mechanism of the rotation flow of liquid crystals is developed. The pump has spiral flow channel in the cylinder electrode. Pressure-flow rate characteristics of the pump are measured. The pressure decreases nearly linearly with the increase of the flow rate under applying the electric field. The maximum pressure increases when we use a liquid crystal with a high dielectric constant for the constant voltage. We confirm that the results of the non-dimensional analysis of the pressure-flow rate characteristics for all liquid crystals are on the same line. This study contributes to the development of a micro-pump in micro-fabricated systems because it needs few parts.
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Yuichi SHIMIZU, Takatsune NARUMI, Tomiichi HASEGAWA
Article type: Article
Session ID: 1409
Published: September 07, 2007
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An estimation method of the flow properties of liquid crystal in an oscillatory flow has been developed utilizing light intensity penetrated a two-dimensional channel. Brightness of the light from a LED through two polarizers under cross Nicol condition and the channel between them was measured by a photo IC. The frequency of the oscillatory flow was able to be estimated from the brightness oscillation. Moreover, the maximum value in brightness oscillation measured had correlations with the frequency and the strain amplitude of the oscillatory flow and was approximately normalized with maximum shear rate in the oscillatory flow.
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Takahiro MURAKAMI
Article type: Article
Session ID: 1410
Published: September 07, 2007
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This paper proposed a new concept of Magnetorheological (MR) fluid damper, which is a passive type MR fluid damper. The passive type MR damper has no electrical devices such as sensor, power supply and power controller, and hence, it has an advantage in reliability and cost compared with conventional MR dampers. Moreover, it can automatically adjust the damping force characteristics in response to its motion. The characteristics of the proposed damper were evaluated by using a numerical code of MR fluid flow. The numerical results show that the damping force is rather dependent on the displacement than the velocity and that the equivalent damping coefficient becomes smaller with increasing the vibration frequency.
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Yusuke KAWAI, Ryosuke IBATA, Hiromichi OBARA, Yasuaki MATSUDAIRA
Article type: Article
Session ID: 1411
Published: September 07, 2007
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This study investigated the effect of the alternating electric field intensity on the generating mechanism of the specific flow structures of the particle dispersion type functional fluid. These specific flow structures contribute actively to a polishing process and to the development of micro fluidic devices. This functional fluid, which consists of suspended micro scale diamond particles in insulated silicon oil, has two specific flow structures under a high-voltage alternating electric field. One is a reciprocating flow structure formed under low electric field intensity and high-frequency conditions and the other is rotational flow structure formed under high-electric-field intensity and low-frequency conditions. This rotational flow structure is induced by the local accreted flows indicated as the characteristic velocity. The electric field intensity affects the movements of the local accreted particle that induce the accreted flow between the electrodes.
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Shinji TOGA, Tomiichi HASEGAWA, Takatsune NARUMI
Article type: Article
Session ID: 1412
Published: September 07, 2007
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The flow fluctuation of an aqueous colloid through a small orifice was measured; the solution included fine particles of approximately 100nm in diameter. Colloids of 1% and 2% volume fraction were investigated using two types of flow channels. In these volume fractions, the surface potential of the particles were composed of electro-static repulsions and a van der Waal's attraction which affected flow property. In this experiment, the electro-static repulsion was controlled by the addition of salt. In the case of flow channel #1, an increase in salt concentration suppressed the flow instability. However in flow channel #2, salt concentration had no effect on the orifice flow. This experiment has shown that orifice flow stabilization effects depend on the channel dimensions.
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Naoyuki OKADA, Hiroshi YAMAGUCHI
Article type: Article
Session ID: 1413
Published: September 07, 2007
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This report describes a swirling flow in rotating pipe section with viscoelastic fluid containing micro-bubbles. Particular attention was given to verify the flow behavior and its associated bubble motion in a viscoelastic fluid, when the dispersed micro-bubble flow is entered from a stationary pipe to the rotating pipe section. The result showed that elongated circulation vortex zones were generated, similar to Newtonian case. From experimental results, with an aid of the numerical simulation, the stagnation point moves towards the inlet region as swirl ratio Ω, is increase. It was also found that the stagnation point further moves toward the inlet in the case of viscoelastic field, showing that the dependence on Re^* becomes infinitesimal. The stagnation point is formed at the upstream in the expansion pipe in comparison with straight pipe.
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Shuichi IWATA, Yusuke YAMADA, Toru TAKASHIMA, Shogo KOMORI, Hideki MOR ...
Article type: Article
Session ID: 1414
Published: September 07, 2007
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A local shear rate due to a local flow of aqueous solution of sodium polyacrylate around a small bubble under mechanical pressure-oscillating was measured experimentally, which can be used to estimate an enhancement in defoaming performance of the fluids. This measurement requires experimental data of tracer velocities distributed around the bubble as well as the bubble diameter over a cyclic period; those enable us to measure the velocity gradient directly. Because the oscillation frequency was too high to record by commercial video camera, we used a high density video camera with a help of strobe scope lighting. We measured velocity field around the bubble successfully. It was found that velocity field was not the same along the bubble boundary, where the velocities in the upper region were smaller than the lower region. In addition, shear rates were compared with the estimated shear rate obtained with the simple sphere model. The estimated values were almost the same each other on the surface of bubble.
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Ayako TAKAGI, Yuichiro IDE, Shinji TAMANO, Motoyuki ITOH, Kazuhiko YOK ...
Article type: Article
Session ID: 1415
Published: September 07, 2007
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This paper deals with flow of aqueous polymer solutions due to a partial rotating disc in a cylindrical casing. The ratio of container radius R_c to disc radius R_d, σ=R_d/R_c, is 0.4, 0.6 and 1.0. As the aqueous polymer solution, 0.5, 0.8 and 1.0wt% polyacrylamide (PAA) solutions are used. The behavior of flow has been investigated using a flow visualization technique. It was observed that at σ=0.4 and 0.6, the ring vortex was formed near the partial rotating disc and it was shed periodically, as well as at σ=1.0. The diameter of the ring vortex B/(2R_c) increases with the increase of the Reynolds number Re_o, in which the relation between B/(2R_c) and Re_o is dependent on the concentration of PAA solutions, not on the ratio of container to disc radii σ. Regardless of the solution concentration or the cylinder-to-disc ratio σ, the height of the vortex is about one-fifth the size of diameter of the rotating disc.
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Shuichi TANOUE, Michal ZIELINSKI, Atsuko UEDA, Yoshiyuki IEMOTO
Article type: Article
Session ID: 1416
Published: September 07, 2007
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We calculated the annular extrudate swell of a polymer melt passing through the rotating-tip tubing die proposed by Gupta et al. (Ref. Int. Polym. Process., 14, 51 (1999)) by the finite element method. The multiple-mode Phan-Thien Tanner (PTT) model was employed as a constitutive equation for a viscoelastic fluid. We changed the rotation speed of the rotating-tip tubing die and the die geometry having straight, converging and diverging flow region. Results obtained are follows. (1) When the rotation speed of the rotating-tip increases, the annular extrudate swells toward the center axis. And the diameter of an extrudate decreases with an increase of the rotation speed of the rotating-tip. (2) The difference of die geometries has an influence on the shape of an extrudate. (3) In case of low flow rate, the geometry of annular extrudate would be independent of the die geometry at a high rotation speed of the rotating-tip.
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Yuji MATSUO, Yasuya NAKAYAMA, Toshihisa KAJIWARA
Article type: Article
Session ID: 1417
Published: September 07, 2007
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We studied the viscoelastic flow in co-extrusion process of multi-layer film by simulating the viscoelastic constitutive model in two dimension. The viscoelasticity of resins affects the flow in a channel, which results in the variation of the thickness of each layer. We discuss the effect of the viscoelasticity in co-extrusion by comparing the results with pure-viscous fluids.
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YUTA Ito, HIROSHI Yamaguchi
Article type: Article
Session ID: 1418
Published: September 07, 2007
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The flow configurations in a gap between coaxially rotating inner spheres and stationary outer sphere were studied experimentally for flows with glass fiber suspended polymeric fluid. In the present study, relatively low concentration polyacryamid-water solutions with glass fiber suspension are used as test fluids. In experiment, two spherical gap sizes are adopted, and Reynolds number, aspect rate of glass fiber were changed accordingly. The frictions torque with inner sphere was measured. From measurement results of friction torque, polymeric fluids follow the power-law model in low Reynolds's number region in two spherical gap ranges. If the aspect ratio becomes bigger, the suspension tends to deport from the power-law model approximation.
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Kensuke ONISHI, Takehiro YAMAMOTO
Article type: Article
Session ID: 1419
Published: September 07, 2007
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Recently, complex fluid that forms structures inside of the fluid is paid attention. Polymer fluids, a representative example of the complex fluid, show different rheological properties from Newtonian fluid. Thus, In this research, the FENE dumbbell model was used to model a solution of polymers without side chain. The Brownian dynamics simulation of shear flows for a system of suspension of model polymers was performed to evaluate rheological properties of polymeric fuid and to analyze the configuration of polymers under shear flows. When the length of model polymer is long, both the shear viscosity and the first normal stress coefficient are large. Brownian force largely affects the rheological property and the configuration at low shear rate.
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Takuya ONOZUKA, Satoshi OGATA, Kensuke KANDA, Ming Yang
Article type: Article
Session ID: 1420
Published: September 07, 2007
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The velocity profile of a dilute polymer solution and a distilled water near the wall surface in a microchannel was clarified using a particle tracking velocimetry technique combined with evanescent wave illumination. Fluorescent particles with a diameter of 100nm were used as tracer particles. The test polymer is polyethylene-oxide (Peo15) solution at 5ppm. The results obtained for the velocity profile of distilled water was found to agree well with the two-dimensional Poiseuille velocity profile at 100nm<z<250nm. On the other hand, the velocity profile of the dilute polymer solution decreases significantly compared with that of a distilled water within 250nm of the wall surface.
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Atsushi YAMASHITA, Kazunori YASUDA
Article type: Article
Session ID: 1421
Published: September 07, 2007
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The flows of aqueous solutions of polyacrylamide (PAA) through microchannel were investigated. Velocity profile in steady flows in straight channel and vortex length at abrupt contraction were measured. The channel is made of two different (hydrophilic and hydrophobic) materials. From the velocity profile measurement, apparent slip was observed at wall surface of the channel. It was found that apparent slip velocity on the hydrophobic surface is larger than that on the hydrophilic surface. As a result, velocity profile become asymmetric to the center line of the channel. However, it was found that the asymmetric profile was not obsreved at the contraction flow.
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Yuki KOBAYASHI, Takatsune NARUMI, Tomiichi HASEGAWA, Tsutomu TAKAHASHI ...
Article type: Article
Session ID: 1422
Published: September 07, 2007
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Elongational behaviors of DNA polymer in micro channel have been directly observed utilizing a fluorescence microscope. Dilute aqueous solution of fluorescently-stained DNA polymer flows in the channel with a sudden contraction. The length of the DNA polymers was measured at three areas, i.e. upstream, contraction and downstream areas. Moreover, the behavior of polymers at the center region and near the wall of the channel was also compared. In the center region of the channel, where only elongational effect is expected, we could not observed extended DNA polymers, because of low elongational rate in this experiment. Obviously extended DNA polymers were observed near the wall at the contraction area even under low elongational condition. However, it was difficult to fully keep the extension of the DNA polymers in shear dominated downstream flow.
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Naoya Adachi, Tomiichi Hasegawa, Takatsune Narumi, Kazunori Sorimachi
Article type: Article
Session ID: 1423
Published: September 07, 2007
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We developed a micro pump using an electric effect. Flow was generated by applying a voltage on both sides of the porous membrane which was immersed in a silica-colloidal dispersion or ion-exchange water, and it was found that the flow is directed toward the negative pole. Experiment were conducted on correlation of interelectrode distance and flowrate.
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Takeshi AKINAGA, Tomoaki ITANO, Masako SUGIHARA-SEKI
Article type: Article
Session ID: 1424
Published: September 07, 2007
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In order to analyze the electrical charge effect on the transport property of microvessel walls, we have constructed an electrostatic model for osmotic flow across a membrane. The osmotic flow is modelled as electrolyte streams suspending charged solutes through charged pores of the membrane. The electrostatic field in the pore, which is governed by the Poisson-Boltzmann equation under the condition of electrical neutrality, was obtained using a spectral element method. The osmotic reflection coefficient was evaluated from the interaction energy between surface charges. We conclude that the osmotic flow could be largely affected by the electrostatic interaction, i.e. the amount of the surface charges, the ion concentration level of the fluid and the size ratio of the solute to the pore. Ion concentration level decreases with the increase of the radius of the pore, under the constant flux rate.
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Junichiro FUKUTOMI, Toru SHIGEMITSU, Masanori KAWADA, Shintarou SAKAI
Article type: Article
Session ID: 1425
Published: September 07, 2007
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Vulcanization molding of rubber product like oil seal is performed by past experience, trial and error. In order to reduce surplus rubber and defective product, numerical analysis of flow phenomena of unvulcanized rubber was performed using FIDAP. The analysis was conducted at constant viscosity without considering the effect of the heat. The results showed that the filling state at external region was difference between experimental and numerical results, but the filling state at internal region represented good agreement between experimental and numerical results. It was clarified from the numerical results that shear stress act during unvulcanized rubber fill up to a narrow channel such as side surface metal insert.
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Toyoharu TAKAHASHI, Hiroshi MIZUNUMA, Nirou TAYAMA, Hiro OGOSHI
Article type: Article
Session ID: 1426
Published: September 07, 2007
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It is known that elderly people's pneumonia caused by swallowing disorder contains high danger of death. However, there is no medical instrument to detect the aspiration. Here, we applied 2D X-ray video fluorography using some care foods to reconstruct 3D geometries of the food bolus. From these geometries, the stress in the bolus was analyzed using a software LS-DYNA. Reasonable swallowing pressure was calculated from the reconstructed bolus model. The maximum swallowing pressure for soft and hard jellies was higher than that for water.
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Takashi NUMAMORI, Hiroshi MIZUNUMA, Mituhiro SONOMURA, Kihei TSUTSUI
Article type: Article
Session ID: 1427
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The viscosity of liquid bolus is raised by thickener additives for patient with dysphagia. However the amount of the thickener additives has been decided by the experience. The appetite declines if the viscosity is raised too much. The method to decide the suitable viscosity is necessary. This study analyzed the swallowing flow using a finite element method. We produced the finite element model for the organs and conducted the coupled analysis between the organs and the liquid bolus. The relationship between the viscosity and the bolus velocity was discussed.
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Hisao YAGUCHI, Takeru YANO, Shigeo FUJIKAWA
Article type: Article
Session ID: 1428
Published: September 07, 2007
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Molecular dynamics simulations of equilibrium state of argon vapor and its own spherical droplet are executed to investigate pressure profile, surface of tension and surface tension at the vapor-droplet interface. Equilibrium states at about 85K are computed for droplet radii (surface of tension) ranging from about 1 to 4nm. Results show that surface tension decrease as the droplet radius decreases. The equilibrium vapor pressure and density also become large as the droplet radius does small. Kelvin equation and Laplace equation are found to be valid even at the system of nano-droplet and its vapor.
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Tomoyasu AIHARA, Yosuke IWASAKI
Article type: Article
Session ID: 1429
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Molecular dynamics (MD) simulation has been performed for nucleation and growth processes of water vapor in atmospheric conditions. The simulated system consists of N_2, O_2 and H_2O molecules. Condition of supersaturated state of water is controlled by density and temperature. Progresses of nucleation and growth are analyzed by internal energy and low wave number structure factor. Dimer and trimer of water molecule are formed in early stage. These collide each other and forms cluster of water.
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Hiroshige KUMAMARU, Kouki HIGASHI, Kazuhiro ITOH
Article type: Article
Session ID: 1430
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Molecular dynamics analyses have been performed on the driving of liquid flow in parallel plates by an electric field. The liquid and the plate materials are water and iron, respectively. It is assumed that some of water molecules themselves are ionized. The width of flow channel, i.e. the length between the plates, is 5nm and 10nm, and 1/500 of water molecules have an electric charge of +1e (elementary charge), corresponding to water solution (strong electrolyte) of 100mM solute. The strength of applied electric field is 1kV/cm. The following have become clear from calculation results. 1) Water flow with positive ions only can be driven by the electric field. 2) Water flow with positive ions in plates with negative ions is similar to that with positive ions only from the view point of liquid flow driving.
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Hirofumi SHINTAKU, Satoyuki KAWANO
Article type: Article
Session ID: 1431
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In the present study, we developed a numerical method to investigate the electrokinetic phenomena in nanochannel. The numerical method calculated electric field and ionic distribution in nanochannel including the electric double layer by numerically solving three dimensional Poisson-Nemst-Planck equation. The accuracy was evaluated from the view point of charge neutrality and the electrokinetic potential at the boundary wall. Using the numerical method, we analyzed the electric field and ionic distribution of potassium ion and chlorine ion in the 100nm rectangular nanochannel at various ionic concentrations. The numerical result showed that the electrokinetic potential agreed well with that from the Graham equation at higher concentration c>1.0mol/m^3, but deviated at lower concentrations c<1.0mol/m^3. This electrokinetic phenomenon in the nanochannel was considered to be induced due to the overlapped electric double layer.
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Itsuo HANASAKI, Satoyuki KAWANO
Article type: Article
Session ID: 1432
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In view of the future molecular epitaxy technique using biomolecules, we have conducted molecular dynamics simulation to investigate the diffusion behavior of biomolecule in the vicinity of inorganic substrate. We calculate diffusion coefficients of lysozymne molecule near silicon substrate in water and that in bulk solution. The results indicate drastically diminished values for near-substrate case compared to that of bulk condition, which is attributed to adsorption of the lysozyme molecule on the silicon surface. The result is in good agreement with recently reported experimental results. The adsorption process is accompanied with substantial deformation. The full atomistic description of the system enables elucidation of the underlying phenomena without direct assumption.
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Satoyuki KAWANO
Article type: Article
Session ID: 1433
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Reaction-diffusion system by Alan Turing (1952) is analyzed for simulation of self-assembled network of 50bp poly(dA)・poly(dT) DNA on mica surface. The theoretical model is well used in the research area of morphogenesis, for example, markings or stripe patterns on animal skin, and the experimental data for validation are accumulated very recently. The comparison of the network pattern between the experimental results using an atomic force microscopy and the simulated results of reaction-diffusion system is made in detail for various conditions. They are in good agreement although the theoretical model is very simple. The result suggests not only the possibility of the prediction tool in the bionanotechnology using DNA but the good example that such a heuristics approach is very significant to understand the behaviors of macromolecules or the complex system.
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Daishi ITO, Tomoaki KATSUYAMA, Hiroyuki TAKAHIRA
Article type: Article
Session ID: 1434
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The influence of gas diffusion is investigated for two kinds of microbubbles. It is shown that a tiny microbubble shrinks accompanied with large surface depression, and does not return to the initial size even after the pressure is reduced. On the other hand, a large microbubble shrinks nearly spherically. The depression of bubble surface suggests the formation of multilayers of surfactant or lipid on bubble surface. A bubble model is also constructed by considering the dynamic surface tension and gas permeation resistance of surfactant or lipid layers. The experimental results are compared with simulations based on the model. The results show that the dynamic surface tension is a significant factor to determine the bubble profile. The results also show that the increase of the permeation resistance during bubble shrinkage stabilizes microbubbles.
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Tadashi SANO, Sigenori TOGASHI
Article type: Article
Session ID: 1435
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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We constructed a bubble detachment model that can be used to help determine the conditions for a stable flow in microchannels. The pressure when the bubbles detached was calculated with the model, and was measured in an experiment using an ethanol-water solution for confirmation. The calculated results agreed with experimental results in an error rate of less than ±9%. This agreement indicated that this model can predict the pressure when bubbles detached and the condition for removing all bubbles in microchannels.
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Hisataka KATAOKA, Hiroaki HASEGAWA, Yu NAGASAKA, Kiyomitsu ASANO
Article type: Article
Session ID: 1436
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Ozone is a powerful oxidizing agent and is also unstable at high concentration. Ozone is capable of bleaching substances and of sterilization in stead of the more common chlorine. Therefore there are requests which are high performance ozone water generation in society. In this study, zeta potential in micro-bubble is measured in order to investigate relation between electrical properties of micro-bubble and ozone water concentration.
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[in Japanese], SINYA MITORIDA, HIROMICHI OBARA, YASUAKI MATSUDAIRA, SH ...
Article type: Article
Session ID: 1437
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper investigated characteristics of the micro bubble valve utilizing a surface tension effect to demonstrate a capability of a flow rate control in a micro channel. The micro valve is operated with controlled surface boundaries of the bubbles generated from two micro channels for air flow at the intersection of the main channel. These controlled boundaries can choke the flow in the main channel so that the valve can control the flow rate. In this study, the characteristics of two types of the micro valve which have a different scale of the air inlet channel width to generate the boundary surface was studied with an observation of the surface boundary shape and with a measurement of the controlled flow rate using a weight method under some flow rate conditions of the main channel managed with a height of the head tank. And the velocity distributions around the bubble surface boundary were measured with a micro Particle Image Velocity. As a result, it proved that the characteristics of the flow rate control effect with the micro valve depend on the blockage ratio and the stretching ratio of the surface boundaries of the bubbles. In the blockage ratio 98%, this micro valve is able to control the 40% flow rate with the wide width type of the air inlet channels.
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Kazuyoshi Jingu, Kensuke Kanda, Satoshi Ogata, Ming Yang
Article type: Article
Session ID: 1438
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In biological, chemical, and medical analyses, the mechanism of particle motion at near-surface is greatly attracted attention for prediction of chemical characteristics such as reaction time and efficiency in micro chip. In this paper, we evaluated concentration distribution of polyethylene latex particle (diameter 100nm) motion at near-surface in micro-channel by total internal reflection fluorescence microscopy. And we investigate interaction forces (van der waals force, electrostatic force and lift force) between particle and wall. The results show the concentration is the lowest at near-surface and shows the largest value at specific location from wall. The location is consistent with theoretical particle-wall minimum potential location in static fluid. In flow field, the largest value location is far away from wall as increasing velocity. This impact is lower with high-ionic strength.
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Hideyuki O-TANI, Masako SUGIHARA-SEKI
Article type: Article
Session ID: 1439
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The flow field around a stationary sphere placed at an arbitrary radial position in a circular cylindrical tube was numerically analyzed by a finite element method applied to the Stokes equation and the continuity equation. The finite element mesh was progressively refined to obtain sufficient numerical accuracy. The results were used to evaluate the shear stress distributions on the surfaces of the sphere as well as the tube wall. It was found that the distribution of the shear stress and its magnitude drastically vary with the radial position of the sphere.
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Jun Shimakawa, Masahiro Motosuke, Shinji Honami
Article type: Article
Session ID: 1440
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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This paper presents a control technique of microflow behavior by locally heated fluid. In microscale, flow behavior is different from that in macroscale, since fluid properties become dominant. Property change of fluids can be caused by photo-induced temperature change. In the present study, A laser focusing system to induce the local temperature gradient has been developed. In order to validate the developed optical system. Velocity measurement was performed by the micro particle image velocimetry technique. During the laser irradiation into a liquid flow in a microchannel, change in the microflow behavior is observed.
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Masanao Takahashi, Tomiichi Hasegawa, Takatsune Narumi, Kazunori Sorim ...
Article type: Article
Session ID: 1441
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Jet thrusts and pressure losses of water through micro orifices and slots were measured by using an electric balance and a pressure transducer respectively. It was found that the thrusts for the orifice of 1mm order agree with the result of numerical simulation using Navier-Stokes equation, but the thrusts for the fine apertures of the order 10μm are well below those predicted. Similarly, the experimental result indicated that the pressure losses for the orifice of 1mm order agree with the theoretical one, but those for the fine apertures of the order 10μm significantly decrease.
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Yuki Ikenaga, Yousuke Ehara, Yasuo Koizumi, Hiroyashu Otake
Article type: Article
Session ID: 1442
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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The pumping effectiveness of the micro T-junction with the oscillatory flow was examined. At one end of the top bar of T, there was a closed tank; Tank 1, that was solid with water. At another end of the top bar of T, there was a tank; Tank 2, that was open to the atmosphere. At the bottom end of the vertical branch of T, there was also a tank; Tank 3, that was open to the atmosphere. In Tank 2 and Tank 3, free surface of water was formed. The 1mm×1 mm cross-section flow path of the 20mm long top bar and 10mm long vertical branch of T were filled with water. By causing boiling and condensation of a bubble cyclically in Tank 1, back-and-forth flow was created at the T-junction. Water surface level in Tank 2 was higher than that in Tank 3. Difference between surface level height in Tank 2 and in Tank 3 was mainly dominated by a back-and-forth velocity at the T-junction. The flow system tested in experiments was simulated by a commercial flow analysis code of STAR-CD. It was confirmed that mass relocation from Tank 3 to Tank 2 occurred when the back-and-forth flow was imposed at the T-junction. The vortical movement around the entry of the branch to Tank 3 that was caused by the back-and-forth flow seemed to cause mass relocation, i.e. the level height difference between Tank 2 and Tank 3.
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Seiichi TANAKA, Hiroshi OSHIMA, Hiroshi TSUKAMOTO, Koji MIYAZAKI
Article type: Article
Session ID: 1443
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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In this study we have tested for large size models of diffuser/nozzle based valve-less micro-pump, which consisted of one diffuser/nozzle element and a variable volume chamber with a cylinder and a piston driven by a direct operated solenoid actuator. Experiment was done for the water and 7 types of the diffuser/nozzle element. As a result of the present study, it was found that the pump performance was improved with the increasing aspect ratio of diffuser/nozzle element, which was correlated with the difference of loss coefficient for diffuser and nozzle flow calculated by commercial CFD code CFX-5.
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Masaki IRIBE, Hiroaki KURODA, Masao WATANABE, Mizuho MATSUBARA, Toshiy ...
Article type: Article
Session ID: 1444
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Nailfold video capillaroscopy (NVC) examines the micro vascular structure noninvasively and aids in the diagnosis of capillary disease, such as Raynaud's phenomenon. We developed high speed digital video capillaroscopy which is composed of high speed digital video camera, deep-focus lens, metal halide light source, and light collecting adaptor. We obtained sequential images of nailfold microcirculation loop with much higher temporal resolution than conventional capillaroscopy. The high speed digital video capillaroscopy enabled us to evaluate quantitatively both micro vascular structure and red blood cell movement. The objects of this study are to measure the radius distribution of micro vascular by Level Set method and also the red blood cell velocity by tracing plasma gap between blood cells.
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Keisuke HONDA, Katsuya NAGAYAMA
Article type: Article
Session ID: 1445
Published: September 07, 2007
Released on J-STAGE: August 01, 2017
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Particle simulations of blood flow in elastic capillary vessel with red blood cells were Comparison was made between blood flow in elastic vessel and blood flow in solid capillary vessel. The elastic capillary vessel was greatly transformed compared with solid capillary vessel. Next, simulation of blood flow in elastic capillary vessel with elastic stricture was carried out. The stricture is expanded according to the passing of RBC. Moreover, RBC passed the stricture transforming its shape flexibly.
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