Cancer metastasis remains largely unexplored, despite remarkable advances in treatment technology. Three-dimensional cultures (spheroids) are being used to attempt to reproduce cancer tissue, and highly reproducible quantitative experimental techniques are being developed. We have developed a method to easily generate cancer spheroids and control their size. In this study, we analyzed cell proliferation within the spheroids and the dynamics of cells escaping from the spheroids by culturing them under normoxic and hypoxic conditions. Breast cancer cells that escaped from spheroids under hypoxic conditions showed increased proliferation and early metastasis-associated migration, suggesting the possibility of induction and regulation of the metastatic phenotype.

The metal engraving technique "KEBORI" as the traditional arts and crafts was reproduced using the latest machining technology with a 6-axis control machining center. In the machining center, the 6th axis control for rotation control of the spindle was installed on a 5-axis machining center. In the previous study, the authors have attempted to reproduce engraving patterns on a flat surface and verified the effects of the method using the 6-axis control machining center and a non-rotational cutting tool. In the present paper, the authors investigated the possibility of processing engraving patterns on a curved surface, which was thought to require more complicated axes control for the machining center.

Currently, drones are expected to be used in a lot of fields. Techniques of drone are tacit knowledge that cannot be expressed in words. Therefore, non-expert spend so much time acquiring techniques to become expert. We aimed to clarify the techniques of the drone. In this paper, we examined the difference between the time spent on the task and the photos taken by the drone. The task includes taking off, going straight, turning, and photographing, which are the basic drone operations. Expert' s time was longer than Non-expert. However, the photo of expert was captured the subject with precision. In the case of Non-expert was off the subject.

Although metallic glass has excellent properties such as strength and corrosion resistance, it has been considered difficult to weld because it is a non-equilibrium material. In this study laser butt welding of Zr55Al10Ni5Cu30 metallic glass and Aluminum was performed. The results showed that the Zr55Al10Ni5Cu30 metallic glass and Al were welded producing burrs. The voids formed at the joint interface were discharged outside the joint with the burrs. A crystal phase with a thickness of about 200 μm was observed on the Zr55Al10Ni5Cu30 metallic glass side along the bonding interface.

The addition of particulate flame retardant to matrix resin is required in order to apply GFRP in the field needed the nonflammability because GFRP doesn’t have fire resistance. There is one way to accomplish this matter is to use two diameter particles (2DP). GFRP that has the two diameter particles added (2DPGFRP) for the compatibility of the suppression of increased viscosity and the grant of non-flammability was noticed in this study. The unique fracture mechanism was shown the 2DPGFRP. That mechanism was clarified qualitatively using the AE method etc. in that study. However, the detailed consideration about parameters except the AE count has not been concluded in our past study. The consideration about these parameters is expected to be clarified quantitatively the detailed fracture behavior. In this research, the fracture mechanism on 2DPGFRP was clarified by the several parameter of AE measurement.

A double lap joint was fabricated using an epoxy adhesive and an aluminum plate, and its high-temperature strength properties were investigated. Tensile and cyclic fatigue tests were performed at test temperatures from -55°C to 135°C. The relationship between test temperature and strength could be expressed using equations derived from thermal activation theory. However, the high-temperature fatigue test changed the molecular structure of the adhesive, resulting in a significant decrease in strength.

The butt dissimilar joints of carbon steel JIS-S45C and die-cast aluminum alloy ADC12 by means of friction stir welding with extended stir zone by friction stir processing were prepared for investigating fatigue properties of the joints. The joints of ADC12 and ADC12 with extended stir zone were also prepared for comparison in fatigue properties. Fatigue tests were carried out under a load-controlled condition with a stress ratio R=-1 in air at room temperature. From the experimental results, it was found that in case of the conventional S45C/ADC12 joints, fatigue fracture were initiated around the border between the region where the silicon particles were distributed as acicular shape and the region where the silicon particles were distributed as fine grain shape. In case of the joints of ADC12 and ADC12 with extended stir zone, fatigue fracture also occured around the border between two types of state in the silicon particles. On the other hand, in case of the joints of ADC12 and ADC12 with extended stir zone, there were cases fatigue fracture occured at welding interface. The reason was thought to be the growth in intermetallic compound at welding interface by extending stir zone process.

In this study, the effect of bonding conditions on the bonding strength between Mg alloy sheet and steel sheet produced by the ultrasonic bonding was investigated. Two types of steel sheets, cold-rolled steel sheet SPCC and electrogalvanized steel sheet SECC, were used. As a result, it was found that the bonding strength varied with the bonding time, the bonding load and the type of steel sheet. Compared to the Mg/SPCC specimen, the Mg/SECC specimen exhibits higher bonding strength due to the contribution of Zn plating film. Furthermore, for Mg/SECC specimens, an increase in bonding time leads to a fracture of the bonding interface and a reduction in bond strength.

Cold splay is considered for use in semiconductor devices because it can produce coatings with minimal thermal degradation. However, the adhesion strength between the ceramic substrate and the copper coating used in this application is not sufficient. Therefore, a method to improve adhesion strength by using an aluminum coating as a bond coating has been reported. In particular, aluminum nitride substrates and aluminum coatings show high adhesion strength, which is thought to be due to scientific bonding via Y₂O₃-derived oxide film on the substrate surface. Since the coating thickness was limited to 80 μm only in these previous studies, we varied the coating thickness in this study to investigate the influence of coating thickness on adhesion strength. As a result, the adhesion strength increased as the coating became thicker.

In this study, fatigue properties and fatigue failure mechanisms were investigated using joints made by applying multiple cross laser spot welds to a 590 MPa cold-rolled high-strength steel plate used for automotive steel. Compared to the joints with only one cross laser spot welding point, the joints with two points applied in the direction of the load axis and the joints with two points applied perpendicular to the load axis both showed an improvement in fatigue strength. It is suggested that the improvement in fatigue strength is due to the increase in bending rigidity in the former case and the dispersion of stress applied to each weld point due to the increase in the number of weld points in the latter case.

In a previous study, we have clarified that addition of aluminum to gray cast iron and heat treatment to form an oxide layer on the surface improved the erosion resistance of the cast iron to aluminum alloy melt. The purpose of this study is to clarify the effect of aluminum addition on microstructure and erosion resistance to aluminum alloy melt of ductile cast iron, which has excellent mechanical properties. Tensile tests were carried out and evaluation of erosion resistance were carried out by immersing the test piece in AC4A aluminum alloy melt and stirred. Addition of aluminum in the ductile cast iron decreased nodular graphite. The tensile strength of ductile cast iron with 1.0 mass% aluminum was equivalent to that of gray cast iron (FC250). Ductile cast iron showed an inferior erosion resistance to that of gray cast iron, regardless of the nodularity. The higher nodularity slightly decreased the resistance, judging from the appearances of test pieces.

The conditions of crack propagation and propagation behavior of composite pressure vessels with artificial defects at the CFRP/Al interface were evaluated when subjected to temperature changes. The prototype vessels with artificial cracks introduced by wrapping Teflon tapes on Al liners were made, and experiments were conducted to cool the inside wall of vessels. During the experiments, strain gauges and thermocouples were attached to the vessels to measure changes in strain and temperature. In addition, a crack propagation analysis for models of vessels with interface cracks was performed using the finite element method under the same conditions as in the experiments. In the experiments, some sudden changes in strains occurred while cooling. In analysis, some sudden changes in strains like that observed in the experiments occurred when cracks grew. The changes differed depending on the positions between crack tips and measurement points. Therefore, these changes can be used to evaluate the amount of interfacial crack propagation in the vessels.-

This study investigates the effects of "laser patterning" using a fiber laser as a mechanical surface treatment for adhesive bonding. The influence of the fracture mechanism by the surface topography of the material was elucidated by strain measurement and observation of cracks during the fatigue test. From the results, it was found that there are two types of failure modes of adhesive bonding, one is the failure mode starting from delamination at the edge which is caused by the deformation of the adherend and the other is the failure mode starting from weak adhesion inside the adhesive around the edge. The laser patterning improved the fatigue strength of the adhesive because it prevented crack propagation near the interface and it increased adhesive area results in a stronger adhesion.

Quantization is a phenomenon that can be confirmed not only in quantum mechanics but also in traffic jams and clustering of rock masses in powder transportation. It is significant to quantize the Navier-Stokes equations that describe fluid phenomena. This paper is discused that the path integral of the Navier-Stokes equation, examine the meaning of the rough path , and obtain the energy flux due to the Rough path based on the renormalization group due to this rough path. Furthermore, for discretizing this energy flux, the Navier-Stokes equation is quantized. From the relational expression obtained for this, and study the phenomenon of high-temperature superconductivity and others in quantum mechanics

It was found that the Reynolds stress included in the Navier-Stokes equation of motion generated a negative quantity of ∇u→ . By canceling out this generated amount, a solution method that satisfied the following conditions was established.

1.Solutions satisfied the Navier-Stokes equation of motion

2.Solutions roughly satisfied the law of conservation of mass

3.Solutions did not diverge even if there were disturbances

Using this method, the turbulent tube friction coefficient of a smooth circular tube could be obtained. It was possible to show that the lower limit of the critical Reynolds number was 2300. Additionally, the method could be applied to analyze the flow around bluff bodies at high Reynolds numbers.

In recent years, the development of supersonic aircraft has become desirable. Reducing wave drag and sonic booms is an important issue in the development of supersonic aircraft. Shock wave modulation technology using electromagnetic energy has been expected to be a promising technique to solve the problems. This technique is based on the baroclinic effect. In order to apply this technique to other vortex generation methods in supersonic flow fields, it is crucial to understand the baroclinic effect. In this study, a three-dimensional numerical code was developed to simulate the interaction between shock waves and temperature modulation fields in order to understand the baroclinic effect caused by electromagnetic forces. The results were verified by comparing them with experimental visualization data, and the relation between the integrated quantity along the eyesight and the local quantity was examined.

In cross-flow turbine, cavitation tends to occur duo to large pressure differences between both sides of the blade because the chord length is short．Therefore the turbine can not apply to a high head. In this study, the critical condition of cavitation occurring were investigated by flow observation, and its effect on turbine performance was clarified by experiments. As a result，it can be clarifilied that the critical condition can be expressed approximated by the linear equation of effective head and NPSHa. In the case of high head and low NPSHa, in which air bubbles are liberated from water, and at low head, in which air bubbles are not easily ejected from the runner inside, the water vapor of cavitation and liberated bubbles formed a large gas-phase region in the runner, and efficiency is not decreased due to preventing water collision with the shaft.

In this study, we investigate the flows around two Savonius turbines that rotate independently by numerical simulation considering the application to ocean current pawer generation. In general, when analyzing the flow around a rotating object, a rotational coordinate system is often used. However, it is difficult to calculate with such coordinate system when two objects rotate independently. Therefore, we use the overset grid that consists of two rotational coordinates for each turbine immersed in a steady coordinate to calculate this turbines’ system. In this study, two-dimensional simulation is performed for two turbines rotating opposite direction, by changing various parameters such as the shape of the blades of the wind turbines, the direction of the mainstream, so that the effect on the dynamic characteristics of the wind turbine was investigated. The results show that regardless of the mainstream direction, the torque coefficient tends to increase as the blade aspect ratio increases, while the torque coefficient tends to decrease as the blade width is reduced.

In turbomachinery, such as gas turbine engines, a region of velocity deficit called wake is generated from the trailing edges of blade rows and periodically passes through the downstream blade rows. When the wake passes over the blade surface it interferes with the boundary layer and the flow around the blade is subjected to various aerodynamic and heat transfer effects. This study experimentally reproduces the unsteady flow field inside a turbine with a periodic wake passing over the blade surface. We have designed and fabricated a small blowout wind tunnel, a wake generator, and a simple model of a flat plate blade. The characteristics of the wake are generated by the moving bars setting of the wake generator. Flow is visualized using the smoke wire method and unsteady velocity is measured using a hot-wire anemometer.

Turbulent pipe flows with a rectifier part composed of several narrow tubes are calculated by the large eddy simulation (LES) incorporated with the immersed boundary (IB) method and the effect of the construction of the rectifier tubes on the turbulent field is investigated in the present work. The bulk mean streamwise velocity increases as the number of rectifier tubes decreases, and that of the calculated rectifier with the smallest number of tubes is six percentage larger than the actual one. Moreover, it is shown that the smallest-type rectifier has the suppression of the turbulence almost like the actual one.

It is expected that lattice-structured heat sinks, which can be fabricated by metal additive manufacturing (AM) technologies, are applied to thermal management components such as heat sinks. In this study, lattice-structured heat sinks consisting of various unit cells (BCC, Octet, Kelvin, Cube) were fabricated by laser powder bed fusion, which is one of the AM processes. The heat transfer characteristics (Nusselt number and Darcy friction factor) of the lattice-structured heat sinks under forced convection were experimentally evaluated using small-sized wind channel equipment. In addition, computational fluid dynamics (CFD) simulations were performed under the same conditions as experiments to validate the CFD simulations and evaluate the fluid flow and heat transfer inside the lattice structures. The CFD simulation roughly reproduced the Nusselt number (Nu) and Darcy friction factor (f) measured by experiments. The unit cell morphology did not significantly affect Nu but contributed to f. The Octet and Kevin unit cells exhibited larger f than BCC and Cube unit cells.

In this study, we present the application of the extended Kalman filter FEM for tidal current estimation analysis in Tokyo bay. As for the governing equation, the non-linear shallow water equation introduced, and the Galerkin and the selective lumping methods are applied to discretize the governing equation in space and time. The observed water elevation are employed in the tidal current estimation analysis, and we examine about the effect of the introduction of the observed water elevation in tidal current estimation analysis.

Abrasive-water suspension jets (ASJs) which jet out the suspension mixed water and abrasive in advance are excellent even at relatively low pressure. Although ASJs system by bypass system is advantageous in terms of equipment maintenance and cost as the jetting time increases the abrasive concentration in the vessel decreases, since high pressure water directly flows into the vessel and pushes out the suspension. In this study, we aim to stabilize the abrasive concentration by the bypass system which has a merit in terms of cost and simple structure and perform highly accurate cuttings. The stabilization of the abrasive concentration was adjusted by changing the opening of the valve attached in the bypass pipeline and changing the flow rate over time. The variation in the flow rate was made based on the equation derived from the equation by formulating the change in the abrasive concentration in the suspension vessel by the differential equation. To maintain a constant abrasive concentration at the nozzle outlet, the bypass flow rate must increase with time. For a constant suspension density, the concentration of abrasive at the nozzle outlet was found to decrease with time.

Karman Vortex structure behind a cylinder placed in pulsating air flow induced by loudspeaker investigated experimentally. Horizontality set up wind tunnel used within the range of Reynolds number set from 60 to 600. In the pulsating flow, lock-in phenomenon occurs in which the vortex generated from the cylinder synchronizes with the frequency of the pulsating flow. In the lock-in condition the frequency characteristics corresponds with f / f_K = 1/2, which is the same as the in-line forced oscillating circular cylinder case. The velocity amplitude in the lock-in condition can be indicate the sum of the velocity amplitude of Karman vortex and pulsating flow. The lock-in region increases with increasing the amplitude of the pulsating flow.

For a baffled vessel agitated by turbine type impellers with six flat blades, the liquid flows produced by the impellers were measured using the particle tracking velocimetry (PTV). The impellers were used in the two configurations for the blades to be open and closed. For the the two configurations of impellers, the time-averaged flow and the turbulence in the flow were evaluated for the regions near the vessel in presence and absence of the baffle. The efficacy of baffles for flow conversion was discussed in terms of the turbulence kinetic energy.

It is known that the baroclinic effect is caused by the interaction between a shock wave and a modulated density field due to the energy input to the flow field, and this phenomenon is expected to be applied to the shock wave-induced vortex generation technology for the supersonic flow control. Understanding the phenomenon of the interaction effect from the view point of the vorticity is important for the practical application of this technology. In this study, a method for quantitatively estimating the vorticity generated behind a shock wave based on the shock wave configuration was investigated by using CFD analysis. The vorticity field generated behind the shock wave in a uniform field agreed between the CFD results and the theoretically derived values based on the shock wave configuration. However, for non-uniform fields, some kind of discrepancy was observed between the conventional theory and CFD results. In the future, we will modify a theoretical method to estimate the vorticity under a non-uniform field.

An experimental study was conducted on the removal of oil film from steel plate surfaces by water containing microbubbles. As experimental conditions, the time for washing steel plates was varied, and the effect of the time on the removal effect was investigated. The effect of water temperature was also investigated. Experiments were also conducted with millimeter sized bubbles for comparison. To quantitatively measure the effect of oil film removal, a fluorescence method was used. A fluorescent agent was mixed with the oil, and the change in fluorescence intensity before and after the experiment was measured. Oil removal rate was evaluated from the fluorescence data. As the result, it was confirmed that the longer the immersion time, the more effective the removal under all conditions. In the bubble condition, microbubbles alone did not show a high cleaning effect, and millimeter size bubbles were more effective. As for the water temperature, higher temperature conditions were confirmed to be more effective in cleaning.

The proposed analytical model for the vertical flows in a gyro-mill wind turbines is studied. The two-dimensional flow structure of the rotating blades is clarified by the numerical calculations using the finite-difference lattice Boltzmann method. The results of the numerical calculation qualitatively agree with those obtained by experiments. The suction flow increases the torque of the rotor blade in upstream, and it suppress a reduction in the torque of the rotor blade in downstream. The results for the sink flow brings reverse action as those obtained by the suction flow.

It is expected that lattice-structured heat sinks, which can be fabricated by metal additive manufacturing (AM) technologies, are applied to thermal management components such as heat sinks. It is important to understand the relationship between lattice structures and heat transfer properties, and optimize lattice structures as heat sinks. In the present study, computational fluid dynamics (CFD) simulations were carried out for evaluating the heat transfer properties of various lattice structures under forced convection. The correlations between various lattice structural features and heat transfer properties or pressure loss were analyzed by the random forest to clarify important lattice structural features for these properties. Four parameters describing the bottleneck in the flow pathway, surface area, and intricate structures were selected. Using the selected structural features, neural network surrogate models were constructed for predicting heat transfer properties and pressure loss of lattice structures. Constructed surrogate models precisely predicted heat transfer properties 106 times faster than the CFD model. Using the surrogate models, the unit cell morphology, number of unit cells, and volume fraction of solids were optimized in terms of the balance between heat transfer property and pressure loss.

Information analysis of a relaminarizing turbulent boundary layer was investigated. The Shannon entropy, proposed originally for the value of information, utilized to quantify the randomness of the data was applied to the flow field. The turbulent boundary layer was relaminarized by the acceleration due to flow convergence. Fluctuating velocity differences between two points separated in the wall-normal direction in the boundary layer were measured by dual single hot-wire anemometers. The Shannon entropy was obtained from the probabilities of the velocity difference. In addition, permutation entropy based on the ordinal pattern of the data was also obtained. At a certain separation between two points, as the height from the wall increases, the Shannon entropy first increases, reaches a maximum and then decreases. This corresponds to the change in the magnitude of the fluctuating velocity difference. At a certain separation, as the height increases, the permutation entropy increases monotonically, reflecting the richness of the ordinal pattern of the extracted data as the fluctuating velocity difference decreases. As the boundary layer becomes relaminarized downstream, the Shannon entropy decreases due to the decrease in the fluctuating velocity difference. Also, although the qualitative tendency of the permutation entropy does not change, the permutation entropy increases slightly due to the abundance of ordinal patterns in the extracted data.

The movement of microbubbles charged with a surfactant was controlled by electric fields and ultrasonic wave. The microbubble was placed in water tank in which electrodes and ultrasonic transducers were attached to side and bottom, respectively. First, the microbubbles were moved horizontally by the electric field generated by the electrodes. Next, the ultrasonic vibrator was activated. The moving microbubbles by electric field were aggregated. As a result, small aggregates were not induced by the electric field, but were captured by the ultrasonic wave. The large aggregates were not captured by ultrasonic wave but were guided toward the electrode by the electric field.

Centrifugal pumps designed for operation in low flow rate have various application such as medical, food processing, chemicals, and manufacturing. However, the efficiency of low flow rate pump is lower than the industrial pumps in general. Therefore, a double rotation screw pump that was different from the centrifugal one was developed to improve the pump performance. In a this pump, the stator rotates passively as the rotor rotates. Therefore, there are two structural gaps: one between the rotor and stator, and the other between the stator and casing. To more improve the efficiency of this pump, it is necessary to reduce leakage losses. In this study, we focused on the gap between the stator and casing and aimed to improve pump efficiency by filling this area several greases to reduce leakage losses.

In our previous studies, it was shown that when the reconnection of two vortex rings occurred, one curvature peak appeared on the vortex ring, which splitted into two curvature peaks at a certain time. Such a stage was defined as the occurrence of the reconnection. In this study, the peak value of curvature at the time of splitting was defined as the critical curvature, and the effects of three parameters (vortex core diameter, vortex ring diameter, and circulation) on the critical curvature were investigated numerically. As a result, the critical curvature was independent on the circulation. In addition, the dependences of the critical curvature on the vortex core diameter and the vortex ring diameter were investigated, and the critical condition for the non-dimensional quantity (the critical curvature multiplied by the vortex core diameter) was obtained. Using such a critical condition etc., the occurrences of the reconnection and the turbulence were discussed.

Heat pipe consists of a sealed container, a working fluid, and a wick, and is divided into three parts: an evaporating section, an insulating section, and a condensing section. It is a heat transport device used to dissipate and cool heat by utilizing latent heat during evaporation and condensation of the working fluid enclosed in the sealed container. However, large increase in heat input causes dryout near the evaporation zone of the heat pipe, which results in that the heat transport ability is lost due to the stagnation of the fluid inside because it does not return to the evaporation zone by capillary force of the wick. The authors are developing a new heat pipe using electrowetting(EW) technique to suppress dryout. EW is a process in which a droplet of liquid is placed on an electrode and the associated dielectric layer, and an electric voltage is applied to the electrode. The contact angle between the droplet and the dielectric layer is changed by applying a voltage. This technique promotes the flow of the working fluid and suppresses dryout by changing the contact angle of the fluid. However, the authors have not found a clear condition under which dryout surely occurs. Therefore, they attempted to investigate the conditions under which dryout occurs and the suppressing effect of EW on dryout by examining the internal pressure and temperature of a newly developed heat pipe. Therefore, by examining the internal pressure and temperature of the newly developed heat pipe, we sought conditions under which dryout occurs and confirmed that EW can improve the cooling capacity of the heat pipe.

The vortex bursting is a high-speed flame propagation phenomenon along a vortex. The vortex driving mechanism of the vortex bursting is explained by using a helical vortex line. Therefore, in this study, we investigated numerically which shape was more valid: the soliton-shape helical vortex line proposed by our research group or the non-soliton-shape helical vortex line proposed by Umemura’s research group. As a result, both of soliton-shape and non-soliton-shape were observed and both shapes were valid. Also, it was found that the location near the vortex core radius was the boundary between the soliton-shape and non-soliton-shape helical vortex lines. Furthermore, when the magnitude of the velocity induced near the flame top was estimated, the contribution of the soliton-shape helical vortex line was the most. Thus, from a viewpoint of the vortex driving mechanism, it was concluded that the soliton-shape helical vortex line inside the vortex core radius play a more important role than the non-soliton-shape helical vortex line outside the vortex core radius.

The flow in the bronchial tube was experimentally investigated using a human bronchial tube model. Resin bronchus model that is made by 3D printer is provided for the experiment. Microbubbles were used as tracers to visualize the movement of particles. The areas to be photographed are the secondary flow in the curved pipe and around the first branch of the bronchial model. Velocity distribution is measured by PIV. Refractive index matching technique are applied to measure velocity in the bronchus model. In the velocity distribution of the secondary flow, a pair of vortex flows can be seen on either side of the inside of the curved pipe. In the velocity distribution before the first branch of the bronchial model, the peak of velocity is observed at the center of the channel during the inhalation process. In the right and left bronchi, the position of the peak is more medially biased due to this effect. In exhalation, the velocity distribution is less biased than in inhalation.

Magnetic particles exposed to a uniform external magnetic field tend to aggregate to form chain-like clusters along the direction of the magnetic field. This formation of chain-like clusters provides resistance to the flow field, which increases the apparent viscosity of the dispersion. This phenomenon is called the magnetorheological effect and magnetically-controlled fluid devises are typical application that are developed by exploiting this effect in the field of fluid engineering. In the present study, we have treated a dispersion composed of ferromagnetic rod-like particles in a simple shear flow to investigate the effect of the particle aspect ratio on the internal structure of aggregates by using Brownian dynamics simulations. The results obtained here are summarized as follows. In the absence of an applied magnetic field, rod-like particles with low aspect ratio aggregate to form stable packed clusters with an increase in the strength of the magnetic particle-particle interaction. On the other hand, rod-like particles with high aspect ratio aggregate to form unstable raft-like clusters. That is, the internal structure of particle aggregates is dramatically changed for change in the particle aspect ratio.

In a previous study, we proposed a novel pH measurement method using a double-barrelled glass microelectrode in which a pH buffer solution and KCl solution were maintained in a glass capillary with a Ag-AgCl wire for the counter and reference electrodes. Applying a galvanostatic current between the counter electrode and the working electrode which was separately in another glass capillary, pH values of sample solutions were identified from the asymmetric current-voltage characteristics. In the present study, the working, counter, and reference electrodes are isolated from each other using a triple-barrelled glass microelectrode to improve the measurement accuracy. Furthermore, a theoretical model is developed to explain the ionic current rectification caused by the asymmetric electrokinetic transport at the interface between the inner and outer solutions, where the electrophoretic transport of protons in applied electric fields and diffusion caused by the concentration gradient of protons are balanced. As a result, the experimental results are deeply understood from the viewpoint of the ion transport phenomena in nanoscale.

When a sphere slowly falls through a worm-like micelle solution, a change in sedimentation velocity accompanied by rapid acceleration and deceleration can be observed. In order to investigate the mechanism of this phenomenon, we measured the stress field around a sphere settling in a CTAB/NaSal aqueous solution using a polarization imaging camera. Behind the sphere, a core part and a sheath structure around the core are formed, and the sheath structure separates the flow inside and outside. A sudden increase in the sphere velocity occurs in two stages of acceleration due to a sudden decrease in tension in the core. A sudden decrease in the sphere velocity occurs due to blocking the core flow through the sheath when the flexible tubelike sheath structure surrounding the core is closed.

We developed an LES analysis method for viscoelastic fluid turbulence by extending the Smagorisky model for LES of Newtonian fluid turbulence. In the extended model, we perform the time-marching correcting the elapsed time at each local location in the flow field so that the time scale for repeating increases and decreases in the intensity of vortex structures in the viscoelastic fluid turbulence is the same as that in the Newtonian fluid turbulence. The amount of the correction at each location is estimated by using a subregion whose size is large enough to properly capture the characteristics of the vortex structure. The size of the subregion is determined from the length of time variation in the minimal flow unit, which is previously performed for each condition of viscoelastic fluid turbulence. In this study, we performed DNS and LES for different types of viscoelastic fluid turbulence with different parameters set in the Giesekus and FENE-P models. By comparing the results, it was shown that LES with the extended model reproduced the DNS results more accurately than the conventional Smagorinsky model. It was proven that the extended model can predict wall turbulence with drag reduction in viscoelastic fluids over a wide range of conditions.

The effects of ozone ultrafine bubble (UFB) formation on ozone concentration and lifetime were experimentally investigated. The results of this study showed that the ozone concentration increased with UFB. It was also shown that the increase in ozone concentration is closely related to the increase in the number of UFBs and specific surface area. Regarding the lifetime of ozone concentration, the half-life of the concentration increased by approximately 1.7 times with UFB conversion. This may be attributed to the fact that ozone-UFB water causes almost no change in mean particle size and particle number over time compared to ozonated water.

The effect of acoustic disturbance on the wake flow downstream of a permeable hollow cylinder was studied. Two counter-facing loudspeakers were placed at the exit of the wind tunnel with its crossing axis orthogonal to the cylinder axis. The frequency of the acoustic wave was selected from 300 to 2400 Hz. Two types of wire-mesh permeable cylinders with different apertures were prepared together with a solid cylinder with impermeable surface for comparison. Velocity fields downstream of these cylinders were measured by LDV. It was confirmed that acoustic disturbances certainly affect the development of the cylinder wake, and in particular, the location where the decelerated flow through the permeable cylinder begins to recover was observed to move upstream or downstream, depending on the acoustic frequency.

The rectifying effect of wire mesh and the turbulent effect of the parallel two-sided grid are well-established phenomena in fluid dynamics. However, the transition process leading to these phenomena are yet to be fully comprehended. In our previous study, the fluctuating vortex structure was confirmed in the transition process of the wire mesh. The purpose of this experiment is to compare the transition process between wire mesh and grid. This experiment focuses on investigating the secondary flow in the near wake of the parallel two-sided grid.

The velocity boundary layer and separated shear layer developed on the circular cylinder surface were measured synchronize with two hot-wire anemometers. When using a constant-temperature hot-wire anemometer near an object, plausible boundary-layer mean velocity and disturbance distributions were obtained by subtracting the voltage increase at no-wind to account for heat transport to the object. The results of synchronized measurements within the boundary layer experimentally revealed that there is a weak negative correlation between the inside of the boundary layer and the separation bubbles, and that the velocity fluctuations are opposite. The results of the velocity distribution measurement at wake placing a reference sensor at the point where the Kalman vortex train forms show a weak negative correlation, despite its far from the cylinder and its weak turbulence intensity in the region. The results suggest that vortex formation affects a wider area than the width of the wake.

An electrostatic precipitator suitable for the collection of aerosol-sized particles is developed. This device is a two-stage electrostatic precipitator divided into a corona discharge part and a collection electrode part. Positive ion is charged to the virus particles by corona discharge, and the negative pole of the collection electrode installed in the later stage collects these particles. The particle collection performance of the system is investigated when the inlet velocity (inlet flowrate) is varied. As a result, even at the same inlet velocity, the collection rate increased with smaller particle size. Furthermore, the collection efficiency of particles decreased with increasing flow velocity.

The effect of an annular L-shaped guide on the thrust improvement of quadcopter is experimentally investigated for ascent and descent conditions. The proposed guide has a side plate perpendicular to the rotational plane and a bottom plate outside the rotor blades. A multirotor model, which consists of four rotors and surrounding guide, is placed parallel or antiparallel to the freestream. The thrust generated by the model is then measured under the condition that all rotors rotate at the same rotation speed. As a result, it is found that the thrust coefficient increases when the advance ratio is small, though it is relatively small compared to the single rotor case. The guide loses effectiveness in high ascent and descent conditions because the drag of the model becomes larger by its bottom plate.

The purpose of this study is to control the jet diffusion by using the deforming nozzle. The shape of polypropylene nozzle can change from square shape into the cruciform shape smoothly. The velocity measurement of the jet flow was performed using X-type hot wire sensors and the constant temperature anemometer. The basic characteristics of the jet flow, such as the velocity distribution, the half value width and the turbulent intensities were obtained. Moreover, to catch the flow feature of the jet near the nozzle the flow visualization was conducted by using the Laser Light Sheet and the high speed video camera. As a result, it has been found that the diffusion of the jet issuing from the deforming nozzle is promoted, comparing with the case of the square nozzle jet.

The effect of the nozzle orientation on the flow characteristics of triple rectangular jets with an aspect ratio of 2 was studied experimentally using an X-type hot wire probe. Four nozzle orientations were tested, i.e., triple nozzles oriented along the major plane (Ma-Ma-Ma) and the minor plane (Mi-Mi-Mi), and triple nozzles oriented with the alternate planes of major and minor (Mi-Ma-Mi and Ma-Mi-Ma). Reynolds number based on the nozzle outlet mean velocity and the equivalent diameter was 1.5 × 10⁴. In upstream of the combined point (CP), the nozzle orientation has no influence on the flow characteristics of triple rectangular jets along the jet centerline. However, the velocity and turbulent kinetic energy near the symmetry line of Mi-Mi-Mi increase more than that of other orientations. In downstream of the CP, i.e., x/d_e ≥ 22, the growth of the half-velocity width of triple rectangular jets decreases less than that of the single rectangular jet due to the axis-switching phenomenon. The jets for Ma-Ma-Ma and Ma-Mi-Ma have a large growth of the half-velocity width as compared to the other orientations.

A fluidic oscillator generates a sweeping jet with high frequency and large amplitude and is characterized by its capability for jet ejection over a wide range and for fluid oscillation by an internal structure that eliminates the need for a drive unit. Recently, the sweeping jet from the fluidic oscillator has attracted attention as an active flow control device. However, there have been no studies on the macro-scale flow structure of the sweeping jet from the fluidic oscillator or the flow mechanism for active flow control. The purpose of the present study is to clarify the macro-scale vortex structure produced by the interaction between the sweeping jet and the main flow by using a numerical simultion.

In order to investigate the influence of the oscillating amplitude ratio to the lock-in range of the circular cylinder which is carrying out the forced oscillation in the direction of a flow, the closed circuit water channel apparatus was used and flow visualization observation was carried out. The used visualization method is a pouring streak method. The experiment was performed combining four kinds of circular cylinder diameters (8, 12, 16, and 32 mm), and four kinds of oscillating half amplitude (2, 4, 6, and 8 mm). All of the flow velocity of those experiments was carried out by 0.04 m/s. Even if changes of the flow pattern at the time of a lock-in differed in the circular cylinder diameter, they were the same. However, when circular cylinder diameters differed also with the same circular cylinder oscillation frequency, it was found that the configurations of the lock-in differ. In the combination of the circular cylinder diameter and oscillating half amplitude, when the oscillating amplitude ratio was the same, it was confirmed that the range of the lock-in becomes almost the same. The lock-in range when the oscillating amplitude ratio is larger than 1 was shown. When the oscillating amplitude ratio increased, it was found that the lock-in range tends to narrow.