Numerical simulation of laminar flows with a pair of streamwise vortices and with a single low-speed streak was carried out in order to investigate the effect of surfantant on a pair of streamwise vortices and the single low-speed. In non-Newtonian fluid flow, the results shows the streamwise vortices were inhibited and the low-speed streak survived. The streamwise vortices existed around the low-speed streak in Newtonian flow, but the streamwise vortices were inhibited at downstream. Low-speed streak in non-Newtonian fluid flow differs in structure from that in Newtonian.

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Turbulent drag reduction due to surfactant solutions was investigated for a small-scale pipeline system composed complex elements. The effects of the counter-ion concentration were discussed on the drag reduction, the viscoelastic characteristics, and the vortex inhibition. When the molar concentration of the counter-ion was ten times higher than that of the surfactant, the drag reduction appeared over the wide range of the surfactant concentrations. The combination of this counter-ion concentration and dilute surfactant exhibited the modest increase in viscosity and the vortex inhibition at high stretching rate.

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Flow reconstruction techniques are a crucial element for feedback flow control. In particular, when we try to install a feedback loop for a drag reduction system using bubble injection, it is necessary to estimate two-phase flow features using a limited number of sensors. In this study, we introduce the stochastic estimation in order to reconstruct unsteady bubbly flows based on point-wise shear stress measurement. We develop a simultaneous measurement system combining four shear-stress sensors and a high-speed camera in a horizontal channel, and reconstruct two-dimensional bubble distribution in the course of time. We investigate the signal processing for the reconstruction algorithm and discuss the capabilities of the stochastic estimation applying to two-phase flows. The results show that the recovered images agree with the two-dimensional bubble distribution in a reasonable degree during the sampling time period at which the linear coefficients are determined. On the other hand, when we apply the algorithm beyond the sampling time period, the reconstructed images agree only for limited time intervals.

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Flow visualization of the turbulent structure in a bubbly channel flow is performed at Re=1333. Kalliroscope is used as the tracer, which is a dispersion of flake-like micros-scale particles with high optical reflection. The optical characteristic of the particle is analyzed by numerical simulation to confirm that the more the reflection intensity increases, the more the shear increases. The results of the application to actual visualization reveal the structures of the streamwise vortices and the low-speed streaks. When the micro bubbles are injected in the channel, the turbulent structure changes to a macular state, i.e. the original longitudinal structure is shortened by the bubbles.

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The influence of wall compliance on the turbulent boundary layer on a flat plate was investigated experimentally by using PIV system and by measuring the pressure on the wall surface. Test compliant wall is made of silicon resin having Young's modulus of E=1.5 MPa, density of p_c=1.20×10^3 kg/m^3, and the thickness t=10 mm. The mean velocities over the flat plate are U_m=105, 175, 260, 330, and 400 mm/s (Re=3.8×10^4, 6.3×10^4, 9.3×10^4, 1.15×10^5, and 1.4×10^5 at x=500 mm). It was clarified that the frequency of the sweep events and the ejection events are decreased only at U_m=260 mm/s by the compliant wall and as a consequence, the generation of the low-speed streaks in the near wall region are controlled. In this case, the pressure fluctuation on the compliant wall decreases, and the spectrum of the pressure fluctuation decreases at F=220 [Hz] (peak frequency of the pressure fluctuation) and at 600 [Hz] < F < 800 [Hz] (natural frequency of the compliant wall).

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Wall-pressure fluctuations and surface displacements were investigated using a flexible tube which has the ability to reduce turbulent drag. Strong correlation of wall-pressure fluctuations and surface displacements were observed. Spectra of wall-pressure fluctuations of flexible tube, which were integrated in a range of non-dimensional frequency between 0.006 and 0.02, keep the lower level comparing to rigid tube. Reduction ratios of the integrated spectra show the similar trend to what drag reduction ratios do for Reynolds number tested.

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This paper describes the drag reduction of square cylinders with the corner-cuttings and with grooves, such as riblet, on the surface of the square cylinders. We carried out wind tunnel tests for the measurements of the drag coefficient, the surface pressure acting on a square section cylinder with chamfered corner and grooves. In addition, the flow visualization by Spark tracing method has been carried out. It is found that the drag coefficients of the square cylinder with chamfered corner and with grooves reduce in comparison with the square cylinder without chamfered corner and without grooves. As the depth of grooves increased, drag coefficient become lower.

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This paper describes an experimental study on the flow patterns and the characteristic of flow around a circular cylinder with grooves. The surface pressure when changing Reynolds number (Re=0.4×10^5〜4.2×10^5) measured with the circular cylinder with grooves of four kinds of grooves number (32, 48, 64, 96) Drag coefficient is calculated from the pressure distribution and the flow around the circular cylinder with grooves is investigated by hot wire and visualization. From the results, It is clarified that minimum drag coefficient shifts to high Reynolds number side as groove number increases. It turns out that wake area, separation point change and the drag coefficient is affected with the number of grooves.

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The micro-structure and trapped air are believed to be key features in drag reduction utilizing water-repellent surface. Previous numerical simulation has shown that the less the liquid contacts solid surfaces, the larger drag reduction on the textured structure surface becomes, though air layer tends to reduce. In this study, we suggest the compound projections of different length as surface texture. Two combinations of the differently sized projections demonstrated much greater water-repellency on the points of drag reduction (>10% reduced) and of the sustainability of air layer, through the experiment and surface observation.

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The purpose of this study is to obtain the new type of the drag reduction for the frictional moment of an enclosed rotating disk by using the fine spiral grooves on the disk surface. The experiments were carried out the measurement for the frictional moment of an enclosed rotating disk with fine spiral grooves, of which there were 120〜160 in the number and 0.1〜0.2 mm in depth, respectively. The Reynolds number range is 4×10^4 &ge; Re &ge; 6×10^5. Test fluids are tap water and aqueous solutions of glycerin. It was seen that the drag reduction occurs in the turbulent flow range at the non-dimensional axial clearance (s/a)=0.011, 0.22 and 0.33, the maximum drag reduction ratio is approximately 15%. The drag reduction depends on the number, the angle and the depth of the grooves. The fine spiral grooves control the secondary flow of boundary layer on the disk and have the effect which delays the generation of the local turbulence in the transition range.

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This paper describes the development of microcapsules for shock wave drug delivery systems (DDS). Especially, capsule structure and driving force is investigated. In the first step, the NMC neutrophil membrane capsule (NMC) is made for DDS instead of polymer membrane capsule. When some part in our body inflames, materials, whose name is cytokine, are released. These materials pull neutrophil, one of white blood cell, toward inflamed part. It is said that neutrophils are moved to inflamed part by gradient of cytokine concentration that is called chemotoxis. This mechanism is immune mechanism. If we can control chemotasis of neutrophil, it follows the development of application in the fields of immunity and drug delivery system. In the second step, the motion of neutrophil by gradient of cytokine is investigated.

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The ultrasound is applied to a medical field; ultrasound imaging, non-invasive treatment of tumors and lithotripsy. The ultrasound also has a potential to deliver some therapeutic materials, such as genes, drugs or proteins, into cells. It is known that microbubbles can improve the delivery efficiency. It is believed that the therapeutic materials can pass through the cell membrane whose permeability is increased by the microbubble destruction, or the ultrasound pressure. In this study, we try to deliver GFP plasmid gene into the fibroblast cell. Ultrasound (frequency=2.1 MHz, duty cycle=10%) is irradiated to the cultured cell through the medium, which contains microbubbles and GFP plasmid. The GFP plasmid transfection can be easily observed by fluorescence microscope. As the results of ultrasound irradiation under several conditions, the delivery of GFP plasmid was confirmed. It is needed to improve the transfection efficiency and optimize some experimental conditions.

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Gene transfer to cancer cells using nanobubbles (NBs) and ultrasound (US) is a non-invasive gene therapy. In order to improve efficacy of gene transfection, the impulsive pressures generated by cavitation bubbles created by the collapse of NBs have to be optimized. In addition, the mechanism of molecular transfer as d as subsequent therapeutic effect has to be investigated. In the present study, we delivered fluorescence molecules into cells with the NB-US method and quantified the intracellular fluorescence molecules. Next we verified the therapeutic effect of suicide gene therapy in vitro using harpes simplex virus thymidine kinase (HSV tk) gene and ganciclovir (GCV), Finally we analyzed the cavitation bubble behavior and the interaction of the shock wave with a lipid bilayer by using theoretical and numerical methods, We attributed the delivery exogenous molecules by the NS-US method to the structural change in the lipid bilayer caused by the interaction of the shock waves from the cavitation bubbles.

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Gene transfer to cancer cells using nanobubbles (NBs) and ultrasound (US) is a non-invasive gene therapy. In order to improve efficacy of gene transfection, the impulsive pressures generated by cavitation bubbles created by the collapse of NBs have to be optimized. In addition, the mechanism of molecular transfer as d as subsequent therapeutic effect has to be investigated. In the present study, we delivered fluorescence molecules into cells with the NB-US method and quantified the intracellular fluorescence molecules. Next we verified the therapeutic effect of suicide gene therapy in vitro using harpes simplex virus thymidine kinase (HSV tk) gene and ganciclovir (GCV), Finally we analyzed the cavitation bubble behavior and the interaction of the shock wave with a lipid bilayer by using theoretical and numerical methods, We attributed the delivery exogenous molecules by the NS-US method to the structural change in the lipid bilayer caused by the interaction of the shock waves from the cavitation bubbles.

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A novel single-mask fabrication method for high-density arrayed micro-orifices and embedded microchannels is proposed for single cell analysis. The process is based on inclined UV lithography to expose a single layered photoresist (SU-8) coated on a patterned mask. Long embedded microchannels with a length/width ratio as high as 1000 can be fabricated by the proposed process. We prepared SU-8 structure with arrayed micro-orifices and embedded microchannels, and carried out an electroporation test with mouse erythroleukemia (MEL) cells to confirm the validity of the proposed system. Nuclear transport factor importinss was fed to the cellular interior by applying the low pulsed voltage.

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Flow structure of water molecules in carbon nanotubes (CNTs) is studied using molecular dynamics method. High density water inside CNTs with diameters of 0.81 to 2.71 nm at a streaming velocity of 100 m/s and a temperature of 300 K is considered with new flow induction models. The results show that the water flow through the CNTs has flat profile that is different from parabolic nature of Poiseuille flow. Hydrogen bond lifetimes are calculated to measure the stability of collective water molecular structure. Comparison with corresponding equilibrium states shows that the stability is not declined by the flow dynamics. Therefore, it can be concluded that the water flow through such small CNTs is pluglike rather than Poiseuille type.

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Gel beads containing cells for immunoisolation should be small, monodisperse and spherical enough to ensure the reproducivility of diffusion of nutrients and hormone and to improve biocompatibility. In this paper, we present a new method to generate cell encapsulated micro gel beads for cell transplants. Using water-in-oil (W/O) emulsification and droplet coalescence in a microchannel, presented method generated smaller (less than 300μm in diameter) and more monodisperse gel beads compared to conventional methods. We report the relationships between flow rate and some essential dimensions for cell transplants such as gel beads diameter and circularity.

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DNA unwinding rates by a single Ku70 enzyme molecule are obscured in the population average of steady state, bulk phase measurements. Measurements of the exact unwinding rate in a micro-channel can be applied to new treatments for cancer, nano-machines, and so on. In this study we prepare a micro-channel, laser tweezers, DNA with micro-beads, and Ku70 enzyme for development of unwinding rate measurement system.

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A novel method to remove dental plaque from teeth, as an alternative to conventional tooth-brushing methods, is proposed. The method is based on ultrasound cleaning, coupled with the use of bubbly water which contains numerous microbubbles. In order to clarify conditions required for the removal of dental plaque, observation of cavitation and pressure fluctuation measurements are performed for degassed water exposed to ultrasound. Cleaning tests with degassed water and bubbly water are performed. For the latter, cleaning tests are made by flowing bubbly water into a narrow gap between an ultrasound transducer and the bottom surface of a shallow water vessel. The results suggest that the performance of dental plaque removal can be significantly improved by utilizing bubbly water instead of degasses water.

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Syringe pump pipetting system uses an air gap to separate sample liquid and system water. To investigate fluid dynamics including elasticity of bubble and damper of system water and tube of this pipetting system, we developed a high-speed gas-liquid interface visualization system to understand the motion of the liquid in a narrow pipe. To predict these dynamics, we developed a simulation method applying a lumped parameter system to use as a tool to see how their fluidic parameter works. Experimental and Simulation results show that after the syringe pump finished its motion, there are still exists gas-liquid interface oscillation, and the tube length has big influence on its behavior.

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We conducted measurements of the radial displacement of the impeller of the centrifugal blood pump which our research group developed, and investigated the effect of the whirling motion of the impeller on the stability of the impeller positions. This study investigated the effect of the configuration of the impeller and the casing on the whirling motion. The amount of leakage flow entering the impeller/casing gap due to the pressure difference had a important role in determining frequency of the whirling motion. The casing having two symmetrical outlet port greatly contributed in minimizing the radial thrust and the shift of the impeller position. The locus under the sudden shutoff of the circuit do not show any deviation from the loci measured under steady flow conditions.

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Velocity and shearing velocity near the volute casing wall in several geometry models of a centrifugal blood pump was quantified by particle tracking velocimetry where higher shear is likely to occur since higher shear has a close relationship with higher hemolysis. As a result, the measurement results of the particle tracking velocimetry were well corresponded with the results from the computational fluid dynamic analysis. Then, averaged shearing velocity powered was correlated with the hemolysis index of the pump.

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This paper describes the visualization of thrombus formation process by using the plasma water to develop the CFD based prediction method of thrombus formation. The experimental apparatus has one orifice pipe that is a simplified model of shear flow in the rotary blood pumps and the stent device. In the first step, the flow in the orifice pipe flow is analyzed by CFD and the shear rate distribution is shown in the case of steady and pulsate flow. In the second step, the thrombus formation process is visualized for constructing the prediction model of thrombus formation. The feature of the experiment is to observe the thrombus formation process by image processing and to quantify the index of thrombus by using blood plasma. Comparing the experimental result with CFD-based shear rate distribution, it is found that the early thrombus is generated at the part where the shear rate of the orifices is high, and the formation speed is dependent on the gradient of shear rate.

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Of course, the space in the human body was limited, so, micro machining technology and the nano technology are the important tools for the development of the various kinds of internal artificial organs. Surface finishing technology with nano level DNA coating, various kinds of nano sensing devices including optical fiber sensor with nano size diaphragm and diamond like carbon nano film, nano actuator, and transcutaneous energy transmission system with nano particle magnetic shielding technology are the common useful technology for the development of various kinds of artificial implantable organs. By the use of these common technologies, circulatory assist systems including total artificial heart with undulation pump, ventricular assist device including rotary blood pump and artificial myocardium, artificial esophagus, drinking stent with peristaltic movements using SMA actuator with nano technology, artificial sphincter and epilepsy control machine are now under development. In this paper, various kinds of artificial internal organs by the use of nano technology are introduced and discussed.

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The undulation pump shows excellent performance for pulsatile operation with small size. The pumping effect is produced by precessional waving motion of a disc inside pump housing. In this study, the effect of clearances between the waving disc and pump housing on hydraulic performance was investigated with computational fluid dynamics (CFD) analysis. The result demonstrates that the circumferential clearance had larger influence on the pump performance than the upper and lower clearances because they were more related to the regurgitation flow. This analysis was validated by comparison with the experimental result.

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