The purpose of this investigation is to clarify the generation mechanism for the aerodynamic force from the flapping wings of insects. In this investigation, a quantitative analysis of vortex field around a dragonfly and an instantaneous aerodynamic force were measured directly using a dynamic PIV and a micro-load cell system. The experimental result showed that the feathering angle of the wing was kept at small value, which generated the leading-edge vortices in downstroke process. The negative pressure field of the leading-edge vortices makes large aerodynamic force in the downstroke process. In the upstroke process, the angle of attack of the flapping wing was smaller than that of the downstroke process. As a result, vortices were not generated, and then the negative aerodynamic force was reduced. These results revealed that the constant feathering angles of both processes play an important role in the aerodynamic force generated by the flapping wings of insects. Moreover, it indicated that the control of the feathering motion is key technology for the development of flapping-Micro Air Vehicles.

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The flow around a circular cylinder, which is placed near a rigid plane boundary, with tangential blowing is investigated experimentally under the condition of Re=2.7×10⁴. The time-mean surface pressure measurements on the circular cylinder and flow visualizations were carried out for various momentum coefficient C_μ and clearances between the circular cylinder and the rigid plane boundary. The fluid force on the circular cylinder was calculated from these surface pressure distributions. The results of experiment show that the lift reaches the maximum value at certain C_μ and then starts decreasing, and this tendency has never been observed for the cylinder placed in the open flow field. It is considered that the phenomenon is attributed to change in the flow pattern around the circular cylinder, more specifically, due to the occurrence of reverse flow in the gap. In addition, the characteristics of the lift forces can be represented by newly defined nominal jet coefficient C'_μ and nominal lift coefficient C'_L.

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The two-dimensional bioconvections in a rectangular chamber have been studied numerically. In this study, our main attention was paid to the behaviors in a large Γ region and the influence of the periodic change of the surface oxygen concentration, where, Γ is analogous to the Rayleigh number in thermal convection. The calculation results are summarized as follows. (1) The increase in Γ has an effect to increase the number of plume. (2) In the large Γ region, we can find the chaotic behavior near the side wall. (3) The periodic oscillation of the surface oxygen concentration has an effect to increase the inequality in the distribution of the bacteria concentration. Moreover, we can find the existence of the optimum frequency for the enhancement of the inequality in the distribution of the bacteria concentration.

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In recent years, CMP (Chemical and Mechanical Polishing) greatly has taken its role as technology of planarizations to produce multi-level inter-connections. While slurry is flowing on a polishing pad in CMP, the polishing pad is in contact with the wafer to polish the wafer surface. Grooves are expected to supply slurry evenly, and to remove wasted particles. Our study aims at developing the design of the best patterns of grooves. By predicting slurry flows between wafers and polishing pads in CMP using CFD, the influence of the slurry flow by the grooved pad can be analyzed. In this paper simulations were carried out for cases without groove, with circular grooves and radial grooves. With analysis of the flow field, how grooves affect the velocity distributions are studied. We also simulated the replacement of old slurry to new slurry, and the roles of the grooves are discussed.

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The effects of flow rate ratio on flow and mixing characteristics for turbulent flow in a countertype T-junction channel have been investigated experimentally. The T-junction was modeled by a mixing tee with square cross sections, in which the mixing channel was connected with the main and counter channels at right angles. Detail distributions of velocity and concentration after the flow merging have been measured using Particle Image Velocimetry (PIV) and Planer Laser Induced Fluorescence (PLIF). Mixing of two flows around X/D=2-5 is enhanced with increase of flow rate ratio, and the concentration fields of the region are largely related to the longitudinal vortices induced by the centrifugal forces. The distributions of the velocity fluctuation in the transverse direction are similar to those of concentration in the mixing layer just after the flow merging. Two-point correlations of velocity fluctuation around the mixing interface were compared with those of concentration fluctuation. These results show that the spatial pattern of concentration fluctuation connected with turbulent mixing is conveyed downstream with extension growth.

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The discussion on the law of the wall has been performed for turbulent boundary layer over rough surface under a zero pressure gradient. The wall shear stress was directly measured with a drag balance of a floating element device. The center of the wall shear stress, which is calculated from the moment of the pressure drag acting on a roughness element, is well consistent with the vertical origin estimated with the assumption of the log law profile. The distance from the crest of the roughness element to the center of the wall shear stress normalized with the roughness height increases with increasing roughness density λ_s. The value approaches to zero less than λ_s=0.5 and tends to 0.5 in the limit of λ_s=1. The roughness function is formulated as function of Reynolds number based on the distance from the crest to the center of the wall shear stress and the friction parameter, which is the ratio of friction velocity to the free stream velocity, for the equilibrium boundary layer over the rough surface. Experimental data collapses on the formula in the case of the constant friction parameter.

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We have investigated aggregation phenomena of a colloidal dispersion composed of ferromagnetic rod-like particles with a magnetic moment normal to the particle axis, by means of three-dimensional cluster-moving Monte Carlo simulations. Concretely, we have treated a monodispersed model system in order to clarify the influences of the volumetric fraction of particles, magnetic interactions between particles, etc., on particle aggregation phenomena. Aggregate structures have been discussed qualitatively in terms of radial distribution, orientational pair correlation functions, etc. The main results obtained here are summarized as follows. Rod-like particles tend to aggregate to form raft-like clusters along the magnetic moment direction as magnetic particle-particle interactions increase. In such raft-like clusters, the direction of each particle axis has a tendency to align in parallel formation, but is not significantly parallel as expected. As the volumetric fraction increases, longer raft-like clusters are formed. However, such raft-like clusters do not aggregate further to form thicker clusters, which is in significantly contrast with dispersions of spherical or rod-like particles with a magnetic moment along the particle axis, where thicker chain-like clusters are observed under certain conditions.

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A damping wave of jet-induced rotary sloshing in a partially filled cylindrical container is theoretically and experimentally investigated to predict the temporal damping of amplitude and visualize a flow pattern inside the rotary sloshing wave. The ordinary differential equation for a loss of energy is established by using the Kármán-Pohlhausen approximation and then the temporal damping of the amplitude is solved. The visualization techniques employed in this study include Computational Fluid Dynamics (CFD) and Particle Image Velocimetry (PIV). Analytical prediction for the amplitude is compared with the computationally and experimentally measured values, and several results for the temporal flow pattern in the vertical cross-section are given.

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In order to survey the wind characteristics of Japan where mountainous terrain is dominant, a large amount of wind data (NEDO Field Test data) that includes more than 300measurement sites in Japan were analyzed in detail, particularly on the turbulence characteristics. As a result, profiles of 90% quantiles of turbulence intensity estimated from all NEDO Field Test data are well approximated by the IEC Normal Turbulence Model (NTM). However, the turbulence intensity levels of more than 65% of measurement datasets exceed the most severe turbulence category (category A) in IEC 61400-1 (Ed.3). Therefore, we conclude that the present IEC turbulence model for wind turbine design do not reflect the severe wind condition of mountainous countries such as Japan.It is considered that this is one of main reason for frequent troubles of wind turbine in Japan. In order to overcome this problem, new criteria for NTM were proposed. The suitability of the new criteria to severe wind characteristics in Japan was discussed.

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Wind characteristics measurement was conducted at one of sites suitable for wind turbine generation in Japan using ultrasonic anemometers and cup anemometers. In particular, it is considered that ultrasonic anemometer is more suitable for analysis of turbulence and gust characteristics, because it does not have moving mechanisms. The reliability of NEDO Field Test data for turbulence intensity analysis used in the 1 st report of this study was evaluated by this measurement data. Gust characteristics in wind models of the IEC 61400-1 (Ed.3) were also analyzed, and those gust characteristics are compared with the current IEC gust model and new gust criteria obtained by integrating the new turbulence criteria proposed in the 1 st report. As a result, it was found that the most drastic gust event measured in this study could be more severe than the Extreme Operation Gust (EOG) model in the current IEC 61400-1 (Ed.3). It was also found that the amplitude of EOG model is adjusted by incorporating with the new turbulence criteria. Therefore, the conformity of the new turbulence criteria to other wind models was somewhat confirmed in this research.

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Unsteady 3-D direct numerical simulations based on the finite-difference method (FDM) are carried out for flow fields around a wind turbine equipped with a flanged diffuser shroud. Generally, it is difficult to simulate numerically the flow around rotational bodies like rotors of wind turbines, because of unsteadiness due to a moving body and complex geometry. Therefore, we have devised an actuator-disc model for a wind turbine for simulating the resistance and rotational forces on fluid. Introduced those volume forces devised from the actuator-disc model into the external terms in N-S equations, the unsteady flow around a wind turbine can be simulated. The results of numerical simulations are compared with the wind tunnel tests and show a good agreement for the velocity and pressure fields.

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In a plug transportation that is one of gas-solid two-phase flow, the predicted equations on particle velocity within a plug and pressure drop in a horizontal pipe have been formulated. The agreement between values calculated by these equations and experiments that changed solid-air mass flow rate, pipe diameter, kinds of particle was obtained. The error between them is almost within 10%. In order to confirm the validity of supposition to derive these equations, particle velocity distribution within a plug in the directions of flow and radius, and particle velocity transformation from a stationary bed to a plug have been analyzed by high speed camera and PIV. As a result, there is no particle velocity distribution in a plug, and particles are accelerated uniformly in extra part of a plug. Particles in a plug are fixed relative to each other and so they all move with the same velocity.

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Linear stability analysis was applied to obtain the critical Rayleigh number Rac at the onset of natural convection for horizontal anisotropic porous fluid layers with vertical thin circular cylinders inserted by variational method with the consideration of non-Darcy viscous flow assumption. The permeability ratio of x-direction to z-direction is 0.5 and the effective thermal diffusivity ratio ξ of x-direction to z-direction for the anisotropic porous fluid layer is less than unity for any circular cylinders with high or low thermal conductivity. The analytical results show that Rac is the highest for the case of ξ=1 and decreases with the decrease in ξ. It decreases with the increase in Darcy number Da and asymptotically approaches to a constant value for Da→∞. The constant value of Rac for Da→∞ is the smallest to be 690.8 for ξ→0. The analytical results were compared with experimental results performed with silicon oil and plastic resin as a working fluid and circular cylinders respectively for ξ=1. The experiment agreed well with the analysis based on non-Darcy viscous flow assumption. The analysis showed that Darcy flow assumption is applied for small Da dependent on ξ.

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This paper presents a numerical analysis method for solving two shape determination problems of temperature distribution prescribed problem in sub-domains and thermal dissipation maximization problem on sub-boundaries of steady heat convective fields. The square error integral between the actual temperature distributions and the prescribed temperature distributions in the prescribed sub-domains is used as the objective functional for the temperature distribution prescribed problem. Each shape gradient for these shape determination problems was derived theoretically using the adjoint variable method, the Lagrange multiplier method and the formulae of the material derivative.Reshaping was accomplished using a traction method that was proposed as a solution to the domain optimization problems. A new numerical procedure using finite element method for the shape determination problems was proposed. The validity of the proposed method was confirmed by the results of 2D numerical analysis.

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Recently, in many fields of science and industry, there is the growing need for the measurement technique applicable to the process in which the viscosity drastically changes within a short period of time. In order to meet the need, we have developed a new viscometry based on the laser-induced capillary wave, which enables very short-time (μs-ms) and small-sample volume (μL-mL) measurement. In the present study, we have developed an analytical technique for solving inverse problem for the determination of viscosity and surface tension by curve fitting of detected signals to rather complex theoretical formulas. We have measured several Newtonian liquid samples whose viscosity ranges from 0.304-7080mPa·s. The results agree well within about 10% from reference values in the wide range of viscosity.

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A living body has a system to maintain its own temperature. We have investigated the heat transfer characteristic common to each organ and therapy. One-dimensional bioheat transfer equation with bioheat generation was transformed to dimensionless form and solved by Laplace transformation on the assumption that biological tissue is homogeneous. Dimensionless steady state solution and transient solution were derived analytically. These solutions can be represented temperature distribution of organ. It is confirmed that these solutions can be applied to estimate temperature distribution of inhomogeneous biological tissue by comparison with numerical solution. It is proved that the size of region where temperature change occurs, steady state thermal penetration depth, is decided by biological properties. Furthermore reaching time to steady state, or the time that biological tissue becomes steady state, is calculated by using these solutions. Additionally temperature chart was proposed for each organs or tissue. This temperature chart can be guideline for medical doctors in the thermal therapy.

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A measurement technique of time-space characteristics of heat transfer to air has been developed using a thin conductive film and infrared thermography. In this work, a titanium foil of 2μm thick and an infrared thermograph of 120Hz were employed for measurements. The accuracy of the measurements was confirmed by comparing the heat transfer coefficient of a laminar boundary layer to the numerical analysis. Also, the dynamic response of the temperature against a stepwise change was confirmed to agree well to the numerical analysis. In order to verify the applicability of this measurement technique to practical measurements, unsteady heat transfer on the wall of a turbulent boundary layer was examined. It was possible to restore the time-space distribution of the heat transfer coefficient up to0.033 sec in time and 4.5mm in space for the conditions of a low heat transfer coefficient of h=10-20W/ (m²·K), by solving the heat conduction equations inside the wall.Consequently, the time-space behaviour of the heat transfer, which was reflected by streaks formed in the near-wall region of the turbulent boundary layer, was revealed, showing that this technique is promising to study the heat transfer to air caused by flow turbulence.

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Effect of non-condensable gas on a micro steam injector (MSI) to obtain a vacuum was experimentally studied. When a pure steam was used in the MSI, the high vacuum condition was obtained. However when the mass fraction of air included in the steam was larger than a cartain value, the MSI became unstable and the vacuum condition could not be obtained. It is considered that the malfunction is due to the instability triggered with the uncondensed steam remained at the throat in downstream of the condensing region. The water nozzle was expected to be a key component to mitigate the effect of non-condensable gas. Three kinds of water nozzle whose flow areas were round, star and screw shapes were used in the present experiment. The star-shaped nozzle where the increased surface area could be expected to compensate the degradation of condensation failed to improve the malfunction of MSI with the non-condensable gas. The screw nozzle expected to drive air away outside the condensing surface could mitigate the effect of non-condensable gas.

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The wind speed distribution and Weibull distribution are essential in the assessment of wind resorce. Linear regression is usually used to estimate the Weibull parameters for a wind data. However, it is known that there could be a large error in the estimated Weibull parameters for a wind data of a complex terrain site. The authors believe that a cause of the error is that the wind of a complex terrain has large turbulence component. Actually, the result of analysis showed that a large value of the turbulence intensity caused a large error of the averaged wind speed of the estimated Weibull distribution. This paper gives an example of a relation between the turbulence intensity and the error of the estimated Weibull distribution and a difference in the estimation by some methods.

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In the previous reports, the heat transfer measurement was performed in a mini-channel boiling system and the thickness of micro-layer that formed between the heating surface and generated vapor with the vapor growth was measured applying the laser extinction method for the narrow gaps and the process of bubble growth was recorded by using a high-speed camera simultaneously. The effects of gap size, the velocity of vapor bubble forefront and the distance from the incipient bubble site were investigated on the micro-layer thickness in a narrow gap mini-channel boiling system and the configuration of the thin liquid micro-layer distributions on the heat transfer surface was clarified. In this study, the mechanism and characteristics of heat transfer were investigated quantitatively by analyzing the affecting factors such as the position of vapor bubble generated, the velocity of vapor forefront, the periods of the micro-layer dominant and the liquid saturation in a boiling cycle and so forth on the basis of the measured data in the previous researches. The heat transfer characteristics were analyzed and the data calculated were coincided with the measured data in the boiling curve for the gap size of 0.5 mm measured in the previous report. Therefore, it was concluded that the boiling phenomena in a narrow gap mini-channel were quantitatively determined by the two kinds of characteristic periods of the micro-layer dominant and the liquid saturated and the characteristic factors shown above.

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One of the main challenges with HCCI engines is structuring thhe systems to control combustion phasing to conduct the stable HCCI operation. Though some HCCI combustion control systems have been suggested, these systems are heavy and have the complex mechanism. In this study, for the development of a small HCCI engine fuelled with DME, a simple HCCI combustion control system was structured, and the control system and the algorithm were evaluated experimentally. In the control system, the ratio of three gases (stoichiometric premixture, hot EGR gas and cold EGR gas) was controlled by throttles. The result showed that combustion phasing was able to be controlled by changing the ratio of hot EGR gas and cold EGR gas with throttles in order to adjust mass-averaged in-cylinder gas temperature at intake valve closure. And IMEP was feedback (PI) controlled by fuel flow rate, and combustion phasing and equivalence ratio were feedback (PI) controlled by throttles. As a result, it enabled them to track the desired values.

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In this study, using simultaneous OH-HCHO PLIF (Planar Laser-Induced Fluorescence) technique, we have obtained instantaneous two-dimensional flame images to investigate highly turbulent premixed combustion in a cyclone-jet combustor. On the phase diagram, conditions of U_m<15m/s for φ_m=0.75 and U_m<20m/s for φ_m=0.90 belong to the flamelet regime, and those of U_m>20m/s for φ_m=0.75 and U_m=30m/s for φ_m=0.90 belong to thin reaction zones regime.In combustion field, HCHO plays an important role at relatively earlier stage of reaction and there is HCHO region mostly in preheat zone at the temperature range of 400 K to 1 400 K. On the other hand, OH exists in reaction zone or burned gas. From simultaneous images of these two species, we have discussed the local flame structure, based on flame length and number of flame regions. When the exit velocity is increased, more cusps appear on the flame front, with larger flame length. Interestingly, it is observed that the flame front is disconnected in some images, corresponding to the local flame extinction.

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Recently, more strict diesel particulate emissions standards are being set in many countries. To have an advantage of low fuel consumption in comparison with gasoline engines, several improvements including combustion conditions in diesel engines have been considered. As for the after-treatment of exhaust gas, a filter such as cellular diesel particulate filters has been widely used. In this study, we conducted fluid simulation in the diesel filter by the Lattice Boltzmann method. The soot deposition was considered for the soot trap inside the filter. The soot combustion was also simulated to burn accumulated soot particles in filter regeneration process. The inner structure of the filter developed by COTEC Limited was obtained by a 3D-CT technique. Results show that the flow pattern is largely changed when the soot is attached to the filter wall, with higher back-pressure. The soot combustion is well simulated to show the effects of oxygen concentration on the temperature and reaction rate.

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This paper investigates a combution control technique for utilizing low cetane number fuels in diesel engines. Two types of light cyclic oil (LCO) with cetane index of 23 and 31 were tested. The influences of the pilot injection on the combustion, thermal efficiency, and exhaust emissions were examined in a single cylinder diesel engine equipped with a common-rail type fuel injection system.The results show that LCO with cetane index of 31 brings higher rate of pressure-rise, higher NO_x and lower smoke emissions compared to diesel fuel because of an enhanced premixing due to a longer ignition delay. However, the pilot injection enables the engine to operate on the LCO smoothly without causing the too high rate of pressure-rise. The pilot injection also enables the operation on the LCO with cetane index of 23 at selected load conditions.

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In order to reduce NOx and smoke emissions from diesel engines with palm oil methyl ester (PME), the combustion characteristics and exhaust emissions of emulsified palm oil methyl ester (EPE) were investigated using a DI diesel engine. From the experimental results, stable EPE can be obtained without adding any emulsifier like as emulsified rapeseed oil methyl ester (ERE). EPE is able to reduce NO_x and smoke emissions as ERE. The optimum water mass fraction for EPE is 15%, with regard to the exhaust emissions. Due to the higher ignitability and better combustion characteristics of PME, EPE with 15 mass% water has shorter ignition delay and lower NO_x, HC, CO and smoke emissions compared to ERE and the emulsified gas oil with same water content. EPE and ERE have higher NO_x reduction and lower smoke reduction, which are normalized by the base fuels, compared with the emulsified gas oil.

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