New measurement method for planar elongation viscosity was developed. A bullet shaped bob is pushed into a sample liquid held in a cylindrical cap with a constant velocity and the resistant force acting on the bullet bob is measured. The bullet bob is designed to generate steady planar elongation flow in the gap between the bob and the cap. The trial experiments were carried out for standard viscous fluids and polymer solutions. The measured resistant force was a function of planar elongation rate. The analytical method and advantage of this measurement method were discussed.

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Jet thrusts outflowing from micro-orifices and capillaries were measured in a range of Reynolds number from 50 to 2000. Jet thrusts were measured as a outflowing momentum by utilizing an electric balance. Experimental results were compared with theoretical ones, and it was found that dimensionless thrusts by capillaries agree with the theoretical prediction but those by micro-orifices are well below the prediction.

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The flow configurations in a gap between coaxially rotating inner spheres and stationary outer sphere were studied experimentally for flows with glass fiber suspended polymeric fluid. In the present study, relatively low concentration polycryamid-water solutions with glass fiber suspension are used as test fluids. In experiment, two spherical gap sizes are adopted, and Reynolds number, aspect rate of glass fiber were changed accordingly. The frictions torque with inner sphere was measured. From measurement results of friction torque, polymeric fluids follow the power-law model in low Reynolds's number region in two spherical gap ranges. If the aspect ratio becomes bigger, the suspension tends to depart from the power-law model approximation.

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An experimental measurement of local flow velocity profile around a small bubble under pressure-oscillatory field obtained by a visualization technique is presented; that is used to estimate an enhancement in defoaming performance of the fluids. This measurement requires velocity data of pigment particles distributed around the bubble as well as the bubble diameter over a cyclic period; those enable us to measure the velocity gradient directly. A high density video camera with a help of strobe scope lighting was used to record the vibrating bubble, because the applied oscillation frequency was more than a frame speed of the commercial video camera. It was found that observed radial velocities were not the same along the bubble surface; the velocities in the upper region were smaller than the lower region, because fluid in upper region was surrounded by the rigid cell wall and fluid pressed from the downside. Shear rates at lower and side bubble surface, estimated by velocity profile of the distributed pigments, agreed well with one estimated by the simple sphere model using time series data of observed bubble diameter. In addition, the fluid was measured by the cone-plate viscometer.

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Virtual Reality is expected to improve the medical and professional technique, and has been investigated on the display for solid shape and touch feeling. In this study, human feeling to spread liquid was virtually expressed using the rheological characteristics of liquid. In order to realize the virtual reality, the liquid thickness and the reaction force were measured in the liquid spreading tests. The influence of shear thinning was investigated for non-Newtonian fluids.

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Recently, supercritical CO_2 has been utilized as a clean plasticizer or a physical foam agent in polymer processing. Those processing are strongly controlled by complex rheological and thermodynamic behaviors of polymer and CO_2 single phase mixtures that come from polymer structure and interaction. In the present study, we measured the shear viscosity reduction of high density polyethylene and ethylene-octene rubber caused by CO_2 dissolution and estimated the viscosity by using the Cross-Carreau-Yasuda model with the free volume theory. It was found that the dependences of shear viscosity on CO_2 concetration, pressure and temperature can be estimated quantitatively with the free volume theory when the occupied volume of polymer is assumed as a function of pressure.

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Rubber products, i.e. oil seal, are produced by vulcanization molding and the vulcanization molding of rubber product is performed by past experience, trial an error. In order to reduce surplus rubber and defective product, numerical analysis of flow phenomena of unvulcanized rubber was performed using FIDAP. The analysis was conducted taken the characteristic of visco-elasticity fluid obtained by experiment, without considering the effect of the heat. The results showed that the filling state of numerical results represented good agreement with the experimental results. And it was clarified from the numerical results that high shear stress acted during unvulcanized rubber fill up to a narrow channel such as side surface of metal insert. In this paper, the flow phenomena under the condition of vulcanization molding are shown and the optimum flow condition would be discussed with experimental and numerical results.

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A servo motor widely used in robot technology was applied to a mixing operation. Periodic interruption of rotation, upward and downward movement and a co-reverse periodic rotation of the impeller were very effective in the liquid mixing. They were especially effective in the high viscosity liquid using a conventional disk turbine impeller. When the periodic interruption of rotation and the co-reverse periodic rotation were used, they were effective at a higher switch frequency for liquid mixing. The larger moving speed and length were effective. In addition, the mixing performance was improved further by the synergy effect of the combination of the co-reverse periodic rotation and upward and downward movement of impeller. Moreover, the mixing performance was improved from unsteady speed mixing at low Reynolds number.

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Effect of Reynolds number on the performance of Darrieus-type wind turbine was tested numerically by 3-D LES (Large Eddy Simulation) analysis. The aim of this study is to judge whether the superiority or inferiority of the Darrieus-type wind turbine performance at Re=E5 works for performance at Re=E6. Tested foil sections were NACA0012 and its modified foil (N-16-12). The main parameters of modifications is maximum thickness position. The turbine is constructed by 3 blades (chord length are 15% of diameter). The equations are discretized by Finite volume method for space and Fractional step method for time. As a result of analysis, The superiority or inferiority of the Darrieus-type wind turbine performance reversed about maximum Power Coefficient and Torque Coefficient, Start characteristic not changed.

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In order to analyze the transient response of a straight-bladed vertical axis wind turbine to change of wind velocity, the response has been analyzed under the condition of either constant rotational speed or constant load torque. Wind that instantaneously increased like a step was generated as the input power. The rotational speed of a wind turbine was controlled by an induction motor in the former condition. On the other hand, the load torque was kept by a powder brake in the latter condition. Experiments under the condition of a constant rotational speed revealed the flow around a rotor followed the wind velocity change of the main flow very quickly. In the case of constant load torque condition, effective torque of the wind turbine abruptly increased up to the value on the torque curve of the final wind velocity, with turbine rotational speed kept almost constant. After that, the effective torque decreased along the torque curve of final wind level to reach the final stage.

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The final goal of this investigation is to develop high performance vertical axis wind turbines for clean energy supply systems. For this purpose, we attempted to simulate flow around a vertical axis wind turbine with LES. Since the angles of attack of VAWT are widely changed during rotor rotation, the large scale separation and interaction between the turbulent wakes are occurred. Therefore, unsteady and high accuracy simulation is necessary to simulate flow around the VAWT. Large Eddy Simulation with sliding mesh technique was utilized to solve the complicated flow around the VAWT. The numerical results show the large separation occurred and unsteady aerodynamic forces were observed in the wake of VAWT. The ratio of negative torque generated period to rotor rotation time was small at tip-speed ratio (TSR) of 3. Therefore, the maximum power coefficient can be obtained at TSR of 3. In the case of high TSR ratio, the predicted results were reasonably agreement with that of the momentum theory. However, the discrepancy of torque coefficient between the results of LES and momentum theory were large at low tip-speed ratio. The discrepancy seems to occur with the effect of dynamic stall. It revealed that the LES is suitable method to estimate the performance of VAWT..

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Effects of spanwise and chordwise blade loading distributions on have been investigated in a three-dimensional aerodynamic design of wind turbines with brimmed diffuser. The aerodynamic design method is based on a three-dimensional inverse blade design method of Zangeneh and an axisymmetric meridional flow analysis. In the inverse blade design method, the blade loading distributions are prescribed by spanwise and chordwise distributions of the circumferentially averaged swirl velocity in the turbine rotor. In the axisymmetric meridional flow analysis, the axisymmetric flow is computed on a meridional plane, including the viscous forces and the blade loading modeled by the blade forces.

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An elastic system with the composite material is proposed to achieve the passive control of the pitch angle of the rotor blade for Horizontal-Axis-Wind-Turbine (HAWT). Through the wind tunnel test with real scale model, we verify the aerodynamic properties of the turbine blade and predict the electric power generation of our paasive control system. We also estimate the influence of fatigue of elastic composite materials in the electric power generation. As a result of the present study, the effectiveness of this system was confirmed. Eeven if the elastic material fatigues due to the periodic external forces, the performance of electric power generation of the turbine with present system is maintained by adjusting the initial pitching angle at the root of the blade.

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Wind resources researches used to be carried out using wind anemometer about 50m in length, but wind turbines at the present day have between 70 and 100 m hub height. In this study, we explained the characteristics of turbulence intensity using the Dopplar SODAR which can measure up wind conditions about some hundreds meters height.

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This paper describes the performance of self-start for vertical axis wind turbine with variable-pitch straight blades . Our aim is to get basic data of performance characteristic of self-start for vertical axis wind turbine. The proposed variable-pitch angle mechanism has an eccentric point that is different from the rotational point. The main feature of the mechanism is to be able to change attack angles according to the rotational angles of the blades without actuators.We measured the performance of self-start for wind turbines of fixed straight blades and variable-pitch straight blades by using an open circuit type wind tunnel and CFD. It was found that the performance of self-start of the wind turbines is dependent on the angle of attachment and the angle of rotation. The static torque coefficient of the wind turbine with variable-pitch straight blades is larger than that of the wind turbine of fixed straight blades.

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A cross-flow wind turbine near a structure with a Flow Deflector (FD) is able to get higher performance than without FD. In this paper, we tried to get optimum conditions of blade number, blade pitch angle and setting angle of Flow Deflector for the performance of a cross-flow wind turbine. The compared conditions of blade number were 10, 12 and 16, blade pitch angle were 30, 45 and 60 [deg] and setting angle of Flow Deflector were 30, 40 and 50 [deg]. The condition of blade number 12, blade pitch angle 45 [deg] and setting angle 40 [deg] of Flow Deflector showed the highest performance of a cross-flow wind turbine near a structure.

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Moment-of-Inertia dependency of transient responses of Vertical Axis Wind Turbines (VAWT) in the abrupt wind speed variation was investigated by wind tunnel test. A device, which can change the moment of inertia of the rotor with no change of the shape of rotor, has been developed. Transient responses of rotational speed were compared with theoretical equations assuming a first order system in order to obtain the time constant. The time constant increases with increasing the moment of inertia.

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It is advantageous for small-scale stand-alone wind turbine-generator systems operated in unelectrified regions to establish an autonomous monitoring. In our target system, a straight-wing vertical axis wind turbine with self-starting capability is mainly operated at a constant tip speed ratio, which means the maximum power coefficient, without an anemometer. This paper develops a detection method of performance deterioration of the wind turbine on the basis of operating behaviors of system in purposely changing its load characteristic. Through numerical analysis using a dynamic simulation model, the effectiveness of this detection method is confirmed.

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We have investigated the wind turbine and two-dimensional wing performance in various fluctuating flows including pulsating flows and turbulent flows with different intensities and scales. As a result, the power outputs of the wind turbine in pulsating flows shows higher values compared to those in smooth steady flows. For a certain condition of turbulent flows, the power output of wind turbine show a higher value than those in smooth and other turbulent flows. In addition, the wing performance improved by turbulence, and the flow around the wing has changed by roughness. Therefore, the possibility that the turbulence with small scales can make an interference with the boundary layer around a turbine blade and improve lift performance is shown.

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We have been groping for the possibility of using wined turbines in the city, by examine the way to harness wind energy near structures such as buildings. The wind turbine used here is a cross-flow wind turbine that has arc shaped blades with blade thickness. In this report we visualized near and inside the cross-flow wind turbine using a smoke visualization wind tunnel. We used two types of light sources (video light and strobe light), and two shutter speeds (1sec, 1/4000sec) to photograph the mean flow shot and snapshot. We compared visualization results with performance measurements at the same condition obtained previously.

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To conserve natural ecosystem and coexist with nature, the authors have proposed a new type hydraulic turbine, named "Gyro-Type Hydraulic Turbine" composed of the blades with high aspect ratio. The rotating plane of the submerged rotor is nearly parallel to the stream, without casings and/or penstocks. Then, this type turbine can be easily applied not only to the mountain torrents and/or rivers but also to the tide power. The fundamental characteristics in the free streams have been presented. Continuously, in this report, it is prepared to apply this type turbine to the tide power.

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Turbo-pumps have weak points, as the pumping operation is unstable in the rising portion of the head characteristic and/or the cavitation occurs at the low suction head. To overcome simultaneously both weak points, the authors have proposed the unique pumping system which is composed of counter-rotating type impellers and the motor with double armatures. The impeller speeds are self-controlled in response to the pumping discharge. Then, the effects of the impeller profiles on the rotational speeds characteristics are discussed experimentally in this report.

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Education practices of maintainable agriculture have so far been tackled. The tower with an elevated reservoir for effective use of rain water was completed in 2005. Then, original measures, such as a visit to a laboratory of a specialist and installation of small hydropower-generation equipment, were taken as a project which employed this hydropower energy efficiently.Judging from the results of a student questionnaire and the analysis of their career choice, this project has had an improving effect on their environmental consciousness.lt proved the validity of our education practice on the subject of hydropower energy.

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The flow in a rotating Pelton bucket is simulated by a Moving-Particle Semi-Implicit Method (MPS). The computed flow pattern is varied with the operating condition, especially, in the high unit speed operating condition, the spilt flow from the cutout can be simulated. The corresponding output power of a runner is estimated under the assumption that each bucket has the same torque variation with its rotation as the computed bucket. The output power of the runner has a tendency similar to that of the model test.

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It is well known that the engineering vibration problems caused by vortex street generated from body in the flow. Therefore, the studies for reducing method of fluids force were carried out. Considering the world interest to unused water resources and micro hydro-energy, it is necessary to think the vibration phenomenon by vortex streets from the point of view of clean energy from streams in river and sea. In this study, we considered whether it's possible to collect the current energy of a river and a sea using the body vibration type induced by vortex similar to wave energy collection. The experimental study was carried out using the 2 cantilever circular cylinder under lock-in condition. To get the suitable relative position for maximum oscillation, the oscillating pattern and vortex street were investigated by visualization test. From these results, the basis data concerning energy conversion from water current to body motion by use of flow-induced vibration were obtained.

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The waterpower has larger energy density than another renewable energy sources, and there are many hydroelectric power stations. The exploitation of the large-scale station with a dam, however, is undesirable because such public works damage natural ecosystem in rivers and/or forests. To promote more and more the hydroelectric generation for the next leap, it is necessary to utilize effectively mini/micro/nano hydropower in coexisting with natural ecosystem. This research develops a new type hydroelectric unit with some submerged blades which yaw in the right and left against the stream of rivers, irrigation channels, and so on. In this report, the concepts of the unit are presented, and the output characteristics and the flow conditions are discussed experimentally and numerically

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The counter-rotating type hydroelectric unit, which is composed of the tandem runners and the generator with the double rotational armatures, has been proposed by the authors. The fundamental characteristics of the unit were investigated experimentally and the design materials of the runners were presented for several hydro-circumstances. Continuously, this paper discusses the effect of the front and the rear runner speeds on the performance and the flow conditions around runners. These results suggest that the cavitation may be suppressed well by the optimization of the front and the rear rotational speeds.

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A ducted Darrieus-type turbine, having a cost-advantage of the simple structure though not yielding so good efficiency, has been proposed for extra-low head hydropower utilization of total head less than 2m. In the case of installing the runner in the duct, a narrow intake type brings about higher efficiency than that of the parallel intake with the same width of runner shaft section. In the latter application, the clearance between the casing wall and the runner pitch circle roles an important factor for turbine performance as flow distortion occurs toward the side wall. Then, turbine performance is severely deteriorated. On the other hand in the former application, effects of the clearance on turbine performance are not clarified yet, though the flow distortion is supposed to become weakened due to the narrow intake before the runner. In the present paper, the effects on turbine performance are experimentally examined with help of flow measurement and the result will be compared with the results of parallel walls. Then the design guideline of ducted Darrieus-type turbine with narrow intake will be proposed.

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The present study is designed to experimentally investigate the flow field past a circular cylinder rotating uniformly and oscillating rotationally in a uniform stream, and identify the wake vortex structures by varying the rotational speed ratio and oscillating frequency. Considering the Reynolds number dependency on flow structures, in this study, experiments were conducted with Re_d = 800, which is larger than a critical value. In order to observe and identify the flow patterns, the flow fields were visualized by the hydrogen-bubble method, and then the flow velocity pattern visualization was applied by using an ultrasonic velocity profile (UVP) monitor. Variation in the wake vortex structure according to the change of the oscillating frequency and the rotational speed ratio was examined.

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In the present study, the authors propose a novel and simple flip-flop jet nozzle, and experimentally show its validity, that is, the controllability on both flow direction and jet-oscillation frequency simply by means of sliding side walls. There exists two kinds of jet-oscillation phenomena. One appears at very short side-wall length, and the other appears at longer side-wall length. For the former, the oscillation frequency equals 3×10^<-3>, and is independent of the Reynolds number, the side-walls breadth and the target position. For the latter, the oscillation frequency is independent of the side-wall length and the Reynolds-number, but varies with the side-walls breadth and the target position.

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Boundary effects with a short annulus ofTaylor Vortex Flow (TVF) called Ekman boundary, are greatly related to the generation of the various modes in vortex structure, which is obtained even in the same Reynolds numbers. Some flows with these vortex structures are useful for cultivation of microorganism which is very weak in shearing flow, because it is said that a TVF has a mild flow characteristic even in higher Reynolds flows. In the present, the spatiotemporal velocity field in the higher Reynolds flow of TVF with a small aspect ratio is visualized and measured precisely by using ultrasonic velocity profiler (UVP) and discussed with the relationship between the flow structure and growth rate of the photo synthetic micro organism.

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In this study, our purpose is to obtain instantaneous and mean velocity profiles in a Taylor-couette vortex flow(TVF) by using a UTDC device based on a ultrasonic generator. The experiment was carried out with a small aspect ratio where the Ekman boundary layer was not neglected. The device has a radial ratio of 0.375, aspect ratio of 3 and the gap length between the inner and outer cylinders of 25mm. As the result, the velocity profiles and their absolute values were in good agreement with those obtained by the Ultrasonic velocity profiler (UVP). This measurement system was applied to the solid-liquid phase flow experimentally, and well measured even in the opaque dilute solution.

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Ultrasonic oscillators and the sound fields produced by them are useful in applications in various industrial aspects, such as measurements, heat/mixture enhancements, cleanings and so on. Recently, according to the development of the UVP measurements, their importance has been increasing. So, we still further demand the understanding of their detailed and precise sound fields, and the development of their simulation techniques. In this research, we develop a simple-and-high-speed computational technique to simulate the sound fields produced by complicated-geometry oscillators, and investigate the optimum conditions for various oscillators, numerically. Moreover, we simulate the acoustic streaming in a cylindrical container, using the simulated sound field. Such numerical results are compared with experiments.

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A new test facility has been constructed at National Metrology Institute of Japan (NMIJ) for calibration of feed water flowmeters used at nuclear power stations at Reynolds numbers of up to 18 million. This very large Reynolds number is achieved at a flow rate of 3.33 m^3/s (12,000 m^3/h) and water temperature of 70℃ in a 600 mm pipe. Then the pipe prover system for 750 m^3/h is also constructed to evaluate the temperature effect on the flowmeters. This paper describes the concept of the new facility, calibration method and some results of evaluation test of facility.

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For appropriate plant management and operation, evaluation of water intake from a river is becoming more important at a hydroelectric power station. Time-of-fright ultrasonic flow-meters (TOP) are mainly used to measure the flow rate in a steel penstock during field efficiency test for hydraulic turbine at a hydroelectric power station. However, those flowrates measured by TOP may significantly differ from the actual flow rates if the flow remains undeveloped or axially asymmetric. As a plant is aging, inner surface of the steel penstock is getting rough, which will cause the change of velocity profile in a steel penstock. Recently, ultrasonic Doppler flow velocity profile measurement method (Udflow[○!R]) is being utilized, which directly can measure the flow velocity profile. Therefore, Udflow make it possible to obtain highly accurate flowrates even if flow is not in ideal condition. In this paper, velocity profile measurements using multiline system were conducted to obtain flow rates with a high degree of accuracy at the national standard loop. Then, we apply this method for the flow rate measurement of steel penstocks whose diameters are 1m-2m in actual hydroelectric power stations. Velocty profiles at different plant power outputs are obtained successfully using Udflow. Measurement results also showed good agreements in the comparison between TOP and Udflow in field efficiency test for hydraulic turbine.

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A multi-beam pulse ultrasonic Doppler method has been developed for a new type of flow metering system. This system, which is under investigation, is a hybrid of time-of-flight (TOF) type ultrasonic flowmeter and ultrasonid velocity profile (UVP) type flowmeter, and it has the advantages of these two types. Our final purpose is to apply the hybrid ultrasonic flow metering system to an accurate flow rate measurement of feed-or recirculation-water in nuclear power plants. The pulse Ultrasonic Doppler method (UDM) has the capability to obtain instantaneous velocity profiles along an ultrasonic beam. The principle of the UDM flow metering system is based on the integration of an instantaneous velocity profile over a pipe diameter. Hence, the multi-beam system is expected to eliminate installation problems such as entry length, and also to follow transmit flow rate precisely by increasing the number of ultrasonic transducers. However, it needs reflectors for receiving ultrasonic Doppler signals. On the other hand, the TOP ultrasonic flow metering system does not need any reflector, but it needs profile factors (PFs) which depend on velocity profiles. PF is one of the important experimental coefficients for the accurate flow rate measurement. Therefore PFs must be corrected according to the changes in flow conditions. In the present study, we evaluated the correction effects of the hybrid ultrasonic flow metering system which can correct the profile factors of TOP ultrasonic flowmeter by using UDM.

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A multi-beam ultrasonic pulse Doppler method (UDM) has been developed for a new type of flow metering system. Our final purpose is to combine this method with conventional time-of-flight ultrasonic flow meter (TOP) as a hybrid ultrasonic flow metering system for an accurate flow rate measurement of reactor feed water or recirculation water in nuclear power plants. The ultrasonic pulse Doppler method has the capability to obtain instantaneous velocity profiles along an ultrasonic beam. In order to measure flow rate with conventional flow meter, flow must be fully developed and stable, therefore a long straight pipe is necessary upstream of measurement point. In actual industrial plants, however, it is difficult to secure long straight line. The principle of the UDM flow metering system is based on the integration of an instantaneous velocity profile over a pipe diameter. Hence, the multi-beam system is expected to eliminate installation problems such as entry length, and also to follow transmit flow rate precisely by increasing the number of ultrasonic transducers. In this paper we investigate the flow velocity profile downstream of 90° pipe elbow experimentally with UDM.

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The authors examined to apply micro-bubbles of 40μm mean diameter generated by the pressurized dissolution method to the measurement of liquid flow field using PIV and UVP (Ultrasonic Velocity Profile monitor) instead of fine solid particles. Micro-bubbles are very economical and ecological compared with solid tracer or reflector particles. We measured liquid flow field about a square cavity and around a circular cylinder using PIV or UVP. The flow field around a rising large bubble in a round vertical pipe is also measured using UVP. According to experimental results, we can recognize the possibility of micro-bubbles for these applications.

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Friction drag accounts for 80 % of the total drag for large ships, and hence microbubble drag reduction is expected as one of the most feasible ways to reduce it because of less environmental impact and easy installation. The basic experiment to confirm the drag reduction effect was performed from 1970's, and it comes to the stage of a practical examination for moving ships. As a method to assess the bubble-originated alternation of the boundary layer structure beneath a moving ship, we have designed a ship-mounting type of ultrasound probe to apply ultrasound velocity profiler (UVP) and examined the measurement performance for a long towing-ship in NMRI 400m-run facility. The probe emits 2MHz-pulsed ultrasound at 75 degree to the main flow direction to acquire the turbulent velocity profile up to 7.2m/s in the fastest case. This report mainly describes the measurement method of bubble distribution in the boundary layer. The method is constructed by the probability theory of ultrasound reflection on individual bubbles, and examined by numerical simulation. This application to a 50m-model ship reveals that the water flow boundary layer changes to steep profile where the bubbles are concentrated.

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In this paper the liquid phase velocity and gas-liquid interface information obtained from UVP measurements are used to estimate the flowrate in a multiphase flow pipeline. The interface is found two different approaches ; by locating the maximum echo intensity at every velocity profile and by finding the maximum variance of the velocity values. The results from the echo intensity method show very good agreement with the actual flowrate. The expected average difference between the flowrate predicted by the echo intensity method and the actual flowrate is ± 5%. That between the variance of the velocity values method and the actual flowrate is -19 to 22 %.

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Ultrasonic velocity profile monitor (UVP) for the flow metering system has been developed. The principle of this system is based on the integration of instantaneous velocity profiles over a pipe diameter. This system is expected to be able to eliminate installation problems such as entry length as well as to follow transient flow rate precisely. In the previous study, the authors reported the results of multi-line flow rate measurement employing this method. However, the previous multi-line measurement requires a lot of ultrasonic transducers. Therefore the system was high cost performance and complicated. From this fact, the authors developed the ultrasonic array transducer for multi-line velocity profile measurements. The array transducer has 128ch elements on the same surface of the transducer. It is very useful techniques because it can measure cross section image using only one transducer. In this study the authors developed multi-line velocity profile measurement system in rectangular channel using UVP DUO with the array transducer. Furthermore the authors applied the array transducer to two phase flow measurements.

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The characteristics of turbulent particle diffusion were investigated in a strong turbulence generated by an active turbulence generator installed to in a small wind tunnel. Instantaneous visualization image analysis was conducted on the plume's meandering motion using a digital camera for grid turbulence(R_λ=52) and excited turbulence(R_λ=526). To clarify the characteristics of the meandering plume, relative diffusion, meandering diffusion and total diffusion, as described in the Taylor's diffusion theory, were obtained by extracting the brightness values from a large number of instantaneous plume image pictures. In the excited turbulence accompanied by a wide inertial subrange, the time dependence on relative diffusion spread σ_r(T) showed almost the same tendency to the Batchelor's suggestions, i.e. 'σ_r∝T in thenear-field', '∝T^<3/2> in the intermediate-range' and '∝T^<1/2> in the far-field'. Meandering parameter σ_m was enhanced near the point source and then gradually increased as ∝ T^<1/2> downstream. Transverse relative diffusion was observed to have non-Gaussian profiles with high kurtosis value of 3.1〜9.6. The 'intermediate-field' was not clearly observed for the grid turbulence where only comparatively small scale vortexes acted, where σm increased only slightly near the source and become to be almost constant in the downstream region. Estimated based on the Gifford's model, the contribution rate of the relative diffusion and the meandering diffusion (σ_r/σ_m 19 to the total diffusion strongly depends on the turbulence Reynolds number of these turbulence fields.

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Thermal diffusion from a point source was experimentally investigated in uniform shear flows having velocity gradients of 2.6, 6.1 s^<-1> and in quasi-isotropic turbulence fields. Short-time dispersion accompanied by the plume's meandering motion was realized in the large-scale turbulence fields of R_λ=310, 410 and 490, with the spectra of temperature fluctuation had clear inertial ranges. For sheared small-scale turbulence of R_λ=50 and 100, the turbulent Prandtl number Pr_t, in almost unchanged in the streamwise direction. The Pr_t was larger than ordinary Pr_t≒1.0, and approached approximately Pr_t≒1.44〜1.88, in the region where the plume's active meandering motion was clearly observed in the sheared large-scale turbulence.

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The effects of external grid turbulence in a free stream on the turbulent boundary layer are investigated by means of the direct numerical simulation (DNS). A square turbulence-generating-grid, on which the velocity and components are set to zero, is located at a short distance downstream of the front edge of the flat boundary with a nonslip condition. The fractional step method is used to solve the governing equations. The results show that turbulence intensities, Reynolds stress, and heat flux normalized by the inner parameters are suppressed in the log-law region by the external grid turbulence.

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The dispersion of pollen was predicted numerically in the eastern Aichi. This simulation was conducted by the diffusion equation. Then, velocity data calculated by mesoscale weather model, MM5, was used. Although the quantity and the timing of dispersing pollen from trees had to be modeled, its quantity was assumed to be constant along a forest in this simulation. The present prediction was carried out on March 6, 2007 when a lot of pollen diffused in the eastern Aichi. The accuracy of this prediction improves by concerning forest distributions, the sedimentation velocity of pollen, the lay of land and so on in the near feature.

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Linear and nonlinear inversion schemes to retrieve collision kernels of droplets in turbulent air flows from the time variation of droplet size distribution are developed. In order to validate the schemes, the collision kernels retrieved by the linear and nonlinear inversion schemes and those obtained by three-dimensional direct numerical simulations (DNS) are compared. The results show that the error of the retrieved collision kernels by the linear inversion scheme is about 24% for the low Reynolds number and increases up to 43% as the Reynolds number increases. On the other hand, the increase in the error of the nonlinear inversion scheme is suppressed, and the error is about 27% even for the high Reynolds number.

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The double-diffusive stratified turbulence whose stratification is composed of temperature and salt is studied by DNS, and the dissipations of passive and active scalars are analyzed. It has been generally believed that when Sc>1, the scalar dissipation scale is smaller than the velocity dissipation scale by a factor of 1/√<Sc> as predicted by Batchelor. However, our results show that the active scalar (Sc>1) in stratified fluid has a dissipation scale comparable to velocity, probably due to the energy exchange between the kinetic energy and the potential energy.

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The Particle Tracking Velocimetry, so-called PTV, is one of the most promising methods to measure instantaneous two dimensional flow fields in detail. The authors have proposed a new PTV algorithm for a high resolution PIV. The proposed PTV is applied to the measurements of flows under wind waves in order to find the down burst phenomenon which is predicted by the previous researches. In this research, high-speed video cameras are used for the dynamic PTV. The velocity distributions obtained by the PTV show the detailed flow structures close to the surface of wind waves. The vorticity distribution

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Three-dimensional Direct Numerical Simulation (DNS) is applied to a wind-driven air-water two-phase flow, and the turbulence structure in boundary layers on both gas and liquid sides near the air-water interface is investigated in detail. The results show that the behaviors of the turbulence structure on the gas side and shear stress and pressure acting on the interface are similar to those over rigid wavy walls. On the other hand, turbulent motions on the liquid side are strongly affected by orbital motion of wind-wave. Beneath the interface of the leeward side of the wind-wave, mean vertical velocity without orbital motion shows negative value and turbulence intensities become large. These suggest that the scalar transfer tends to be enhanced in this region.

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The effects of swell on mass transfer across the wind-driven air-water interface was investigated through laboratory experiments in a large wind-wave tank. The swell was mechanically generated and propagated in the same wind direction. The CO_2 transfer coefficients on the water side were measured at upwind region(x=4.0m) and downwind region(x=10.0m) through reaeration experiments of CO_2. The results show that CO_2 transfer coefficient for swell wind wave case decreases campared with that for pure wind wave case. Furthermore, the damping effect of swell is well correlated with the ratio of significant wave height for pure wind wave to that for swell irrespective of fetch, whereas that is poorly correlated with free-stream wind velocity U_∞. The damping effect of swell is distinguished in the case that the ratio of significant wave height for pure wind wave to that for swell is about 0.5.

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