Organic light-emitting devices (OLEDs) are expected to be the next generation flat panel displays and have been commercialized for mobile phones and car audios. In addition, the performance of white-light-emitting OLEDs have been steadily improved and, today, they are considered to be the light source of the next generation. In this talk, the recent development of high performance OLEDs for general lighting will be discussed, and the challenges by Yamagata Prefecture will be introduced.

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Medical applications of ultrasound such as High Intensity Focused Ultrasound, Extracorporeal Lithotripsy and ultrasound contrast agent imaging have recently been the subject of much interest as the medical application of fluid dynamics. In these applications, nonlinear bubble motion facilitates the medical treatment by improving the image quality or enhancing the therapeutic effects through localized heating, erosion or acoustic emission. Utilizing those phenomena, a diagnostic and therapeutic integrated system can be developed. It is essential to understand ultrasound propagating and heating phenomena in a human body, which is inhomogeneous medium, and enhanced local heating phenomena by micro bubbles. In this paper, medical applications of ultrasound with microbubbles, acoustic cavitation and ultrasound propagation in human body are highlighted.

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In this paper, the Liquid Rocket Engine Development Planning and Expectation in Japan are described based on LE-5/ LE-7 Development Results and Actual flight Results. In USA Apollo era, Design Criteria was prepared synthesizing their enormous Failure Experiences and was published in general. For the next development, Design Criteria or Failure Limits have to be prepared at our own efforts. It is important to take up Failure Investigation, Simulation or both merging effort in early phase, to realize the rational and optimum Design.

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In order to develop a new mixing procedure, we conduct DNS (direct numerical simulation) of vector control for free jet. The nozzle is periodically oscillated by vector control. From view of instaneous vortex structures, it is found that the structures are associated with oscillating frequency of the nozzle. In contours of ensemble averaged streamwise velocity, the jet diffuses largely in the oscillating direction. An increasing in mixing of the vector controlled jet is observed in mean entropy distribution. Therefore, the vector control can be expected for the improvement of mixing efficiency.

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In order to establish the lateral boundary conditions of a high accurate DNS (Direct Numerical Simulation) for round jets, we propose the new hybrid scheme, in which sine or cosine series and 6th order compact scheme are used for the discretization. Compared to the experimental data concerning a free jet, it is found that the proposed scheme is capable of predicting well the flow properties such as mean and fluctuating velocity. Also from the mean velocity vectors and entrainment quantity, it confirms that the entrainment can be captured correctly using the present scheme.

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The laminar-turbulent transition of a mixing layer induced by oscillating flat plates at an exit of a two-dimensional nozzle was experimentally investigated. The mixing layer was formed between the jet which issued from the nozzle and the surrounding quiescent fluid. The plates oscillated vertically in relation to the mean flow. The oscillation frequency was two orders of magnitude smaller than the fundamental frequency of the velocity fluctuation. The disturbance traveled downstream as the convective instability, though it was damped only far downstream. Fluctuating energy production and convection rates that contribute to the streamwise and normal fluctuating velocities became maximum at different streamwise stations. The stations did not correspond to the respective positions where the fluctuating velocity became maximum in the streamwise component, although it corresponded in the normal component.

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A dielectric barrier discharge (DBD) plasma actuator has been investigated as a device for flow control by many laboratories. In this study, we try to use it for jet diffusion. In order to achieve mixing enhancement of jet flow, we focus on two parameters, voltage and frequency of plasma actuator, to examine how induced velocity and turbulence occur. This time ,We examined how the induced flow with the plasma actuator electrode dimensions occurred. It is because that we guessed the more induced flow speed, the more influence to the jet flow. Concretely saying, we measured the flow speed setting the voltage and the frequency. As a result, the most effective and safest condition to generate the induced flow was discovered.

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The purpose of this study is to reveal the suppression mechanism of an edge-tone generated by jet-wedge interaction. A passive control was achieved by means of a pair of side plate attached near the nozzle exit along to the jet issuing direction. Velocity measurement was conducted to clarify the effect of the plate on the edge-tone suppression. The characteristics of flow through a gap between the side plate and nozzle tip was investigated. Then it is revealed that the entrainment plays an important role to vary the sound property associated with the flow field patterns.

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The interfaces between turbulent and non turbulent regions in two-dimensional turbulent jet are investigated using conditional-sampling and ensemble-averaging techniques. The measurement is done by using the combined probe for the simultaneous measurement of instantaneous static pressure and two velocity components to investigate the flow structure and the vortex structure at the interfaces. Experimental results show that the thickness of the interface is about 0.08 times the half-width of the cross streamwise profile of the mean streamwise velocity and comparable to the Taylor microscale. There is a sharp pressure drop in middle of the interface and suggests the existence of vorticity.

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The method for estimating the circulation of optimal vortex ring generated by a pulsating jet flow has been investigated experimentally with PIV measurement. The periodical change of flow rate was conducted by sine curves under the conditions of amplitude Reynolds' numbers Re_0 of 1200〜5040 and Womersley numbers a of 12.5〜24.4. The results indicate that the formation time of the optimal vortex ring can be estimated using the condition which the optimal vortex ring is formed when the propagation velocity of vortex core is equal to the convection velocity of shear layer of jet flow. Each of the velocities is expressed as empirical formulations with pulsating jet conditions. Therefore, the formation time of the optimal vortex ring can be estimated from the pulsating jet conditions, when the circulation of vortex ring stops growing. The circulation of vortex ring estimated using the present method is in good agreement with the measurement data within 5% error. The circulation of vortex ring indicates the local maximum value with a specific Strouhal number.

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To control the re-circulating region of an annular jet, we introduced disturbances by means of a gap in the exit end of the nozzle and periodic pressure fluctuations through the nozzle inner body. The effects of these disturbances on the flow structure in the developing region of the jet were investigated by LDV method. Results for the annular nozzle with a fixed outer diameter of 50 mm and exit velocities from 5 to 40 m/s are described.

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We analytically examine the nonlinear instability and breakup phenomena of a viscous compound liquid jet which consists of core and surrounding annular phases. Applying the long wave approximations to both phases, a set of reduced nonlinear equations is derived for large deformations of the jet. Breakup phenomena are numerically examined when sinusoidal disturbances are fed at the end of the semi-infinite jet. Typical breakup profiles are shown for the surface tension ratios and Reynolds numbers. In particular, for sufficiently small Reynolds number, the core phase is found to be choked at a bottle neck of the jet, which is followed by ballooning of the annular phase in the upstream. It is shown that there exit the most unstable frequencies of input disturbances for each parameters of the surface tension, viscosity and amplitudes of disturbances. From variations of the breakup time and distance for such frequencies, it is expected that there exists a critical Weber number, above which the jet becomes convectively unstable and below which absolutely unstable.

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When a low density gas compared with the ambient gas is issued from a round nozzle, radial ejections of jet fluid are generated at near the nozzle exit. This phenomenon is called a side-jet. It is thought that the density ratio between the jet fluid and the ambient fluid, the jet Re number, and the momentum thickness at the nozzle exit are conditions for the side-jet formation. The momentum thicknesses and shear stress in variable density jets were measured using a hot-wire probe and a hot-wire concentration probe. The side-jet formation was observed by flow visualization. The condition for the side-jet formation can be displayed in the domain between the density ratio and the non-dimensional momentum thickness.

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Flow structures of a buoyancy jet in a grid turbulence field and in a flow field without a turbulence grid were investigated by flow visualization with a high speed camera and tracer technique. The present experiments were conducted for changing the mean velocity of a cross wind, jet velocity and temperature difference between the cross wind and the jet. The flow structures of the buoyancy jet were divided into three modes. Their modes were affected of interaction between the cross wind, the jet and the buoyancy. Bifurcation phenomena of the jet occurred when the effect of buoyancy force was dominated. The Strouhal number of vortices generated by the velocity shear was different in the each field. The streamwise length of vortex formation region just behind the jet exit was shorter in the grid turbulence than in the low turbulence field, because turbulence intensity affected on the process of vortex formation.

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Skin friction coefficients have been estimated by means of the momentum balance analysis. But It was revealed that the concordance rate of the measured values is not good. In this study, distributions of the mean velocities and fluctuating velocities in a cross section of a fully-developed flow region were measured in two ways, one by fixing the probe posture of I-, X-type probe in the streamwise direction, and the other by rotating the I-type probe. This study shows the distributions of five components of the Reynols stress in the lateral plane and symmetry plane. And the establishment of the similarity law related to the Reynols stress distribution was assumed.

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Studies on near wall turbulence in three dimensional turbulent flow are reviewed with an emphasis on structural change of the turbulence by the imposed cross flow. The asymmetric response of the quasi-streamwise vortices of different signs to the cross flow are important to understand the reason of the reduced Reynolds shear stress in 3D flow. Flow developments around the streamwise vortcies give us useful information of the flow physics in 3D flow.

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A continuous inkjet printer is mainly used in industry for marking and coding of products and packages. Pressurized ink subjected to the piezoelectric vibration is continuously ejected from the nozzle vibrating at constant frequency. Ink droplets are formed beyond the breakup length due to Plateau-Rayleigh instability. The droplet formation processes from nozzles of different direct lengths were investigated by both of the experiment and numerical simulation. Droplet patterns are visualized for different values of droplet formation constant and the applied voltage to the piezoelectric vibrator. These patterns are classified by the droplet formation constant versus the applied voltage to the piezoelectric vibrator diagram. Satellite-free conditions have been determined. Similar patterns are obtained by numerical simulation as compared with the experimental observations.

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A synthetic jet is one of the methods of generating the jet and a synthetic jet actuator has been shown to be a useful tool for flow control. For the separation control, it is necessary to clarify the periodic behavior of the synthetic jet. In this study, the effect of excitation frequency on behavior of the longitudinal vortex in the case of the synthetic jet in a crossflow is investigated. Wind tunnel experiments are carried out using a hot-wire anemometry and the flow visualization technique was used to aid in understanding the vortical field. For f=60 Hz and 100 Hz, the synthetic jet promotes mixing and agitation in contrast to the f=200 Hz case. The longitudinal vortex generated by the interaction between a jet and a crossflow was not observed for f=200 Hz. The generation of the longitudinal vortex is affected by the synthetic jet frequency.

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The velocity field of the controlled jet is measured x-type hot wire probe. From the result of power spectrum analysis of streamwise velocity fluctuation at the nozzle exit, in the case of VR=1.0, a resonant mode is found for the frequency of acoustic excitation, and this resonant mode contributes to the promotion jet diffusion. In the case of VR=0.5, a lot of mode are found and non-liner interference between different modes. This non-linear interaction between different modes seems to suppress the radial direction velocity fluctuation of the film flow, and seems to restrain the diffusion of the jet.

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We discuss two fundamental flow schemes of liquid lithium planned for the target and coolant of BNCT (Boron Neutron Capture Therapy) using accelerators which makes tumors curable with cell-level selections. Our objects are the flows in a high-vacuum because of operating accelerators, and they serve both as a target of accelerators and as a coolant for the target itself. The latter role requires high-speed flows for sufficient removals of proton beam heating. In this paper, we compare the momentum defects of the film flow on a flat guide plate with that of the sheet jet.

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In this study, the flow features of vortex shedding from tandem arranged circular cylinders oscillating along the direction of the flow and its characteristics of fluid force were simulated using a vortex method at the ranges of interval ratio L/d=1.5〜5.5, the amplitude ratios 2a/d=0 and 0.25, the frequency ratios f/f_k= 1.6 and f/f_k=2.8 and Reynolds number Re=620. As a result of calculations, it was confirmed that the calculated flow patterns of stationary case were in reasonable agreement with previous experimental results. The variation of fluid force and vortex shedding frequency was shown for every interval ratio L/d of tandem cylinders, and relationship between the 1st cylinder and the 2nd cylinder was clarified. In the flow pattern of oscillating tandem cylinders, although the vortex street of mushroom section form was formed, the twin vortex street was not formed. The influence of vibration appears notably in the 2nd cylinder.

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The objective of this study is to investigate the decay law of oscillating grid turbulence in a rotating tank. To improve the performance of rotary machines by suppressing fluid resistance, it is important to understand rotating turbulent flow. In this study, a water filled tank was rotated, and oscillating grid turbulence was generated in the rotating tank. Hereby, effect of the rotation and the grid stroke on the flow field was examined experimentally. Quantitative evaluation by PIV measurement of the flow field suggested that as rotation increase, suppression of turbulence decay increase. It was demonstrated that this phenomenon appeared more particularly at longer grid strokes.

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This study is concerned with the flow around a circular cylinder that a Dielectric Barrier Discharge (DBD) plasma actuator is located at the cylinder surface. Flow visualization and the base pressure measurement were carried out for the case that the plasma is on and off controlled (pulse modulated drive). As a result, the wake expansion and the length of cavity region are significantly changed. The base pressure decreases when the actuator is driven at a frequency of St=0.4, and it increases at St=1.

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Entropic lattice Bolzmann model (ELBM) is known as the method enhancing stability by satisfying the second principle of the thermodynamic by imposing the monotonicity and the minimality of the H-function. But the validities of the results, especially for unsteady flow, were not comfirmed sufficiently. In our previous study, we applied ELBM to a 2-dimensional channel flow past single square cylinder, and found that the validity of ELBM is guaranteed under the condition of rms value of viscosity difference ratio Δ_<0rms> Δ_<0rms>&le;0.24. But the generality of the condition have not been confirmed. In this study, we applied ELBM to a 2-dimensional channel flow past two square cylinders arranged side by side in Reynolds number region Re = 100 and 1000 and investigated the effect of number of cylinder on the validity condition. As a results, it was found that as well as the in the case of single square cylinder, the condition Δ_<0rms>&le;0.24 is also almost reasonable in the case of two square cylinder.

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The aim of this study is to investigate on vortex behavior behind a circular cylinder by introducing jet with dielectric barrier discharge (DBD) plasma. The electrode of DBD plasma was mounted on the circular cylinder. A constant AC wave with voltage of 2kV and frequency of 10kHz is applied to the electrode. The forward and spanwise jets to the main flow direction were induced by electrode arrangements. The flow behavior behind a circular cylinder is measured by hot-wire anemometer and visualized by a high speed video camera at Reynolds number of 1.Ox1O^3. We confirmed the flow structure in the wake and the vortex behavior using the plasma actuators.

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The transient aerodynamic characteristics of the unsteady force are investigated by varying impulsively the incidence of the airfoil beyond the stall angle. In this study, we measured unsteady fluid force acting on the airfoil simulating a human hand in swimming using load cells and visualized vortices in the wake in a wind tunnel. We also examined the relation among fluid force, angle of attack, and rise time. As a result, impulsively varied incidence makes an angle of the static stall larger and also the lift coefficient larger. We investigated the dynamic flow vector and vorticity fields at Reynolds number 1.O×10^5.The vortex shedding from the airfoil cause s the changes in the transient characteristics.

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A blade which has fluctuating pitch angle influences on the air field around itself. The purpose of this study is to investigate unsteady aerodynamics which acts on a turning plate by Particle Image Velocimetry (PIV). This technique makes us possible to access the flow field around the fluctuating pitch angle of the blade. Comparison of the flow fields between a turning flat plate and non-turning flat plate indicates drastic differences even in the same attack angle; i.e. flow direction, appearance of the flow separation, width of the wake and so on. Phase averaged velocity distribution in a range of the angle shows periodic generation of vortex.

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Flow field around a moving body is treated as Fluid-Structure Interaction (FSI), and these phenomena have been continued a series of moving elastic deformation of the body, vortex generation, growing and development. Recently, the development of MAV and micro flapping robot applied the mechanism of insect flying respectively, and have been clarified the elastic deformation of the wing. However, these flow field and characteristics of dynamic force have not been clarified completely. In this paper, we simulate the fluid structure interaction simulation of flow field around an elastic thin film and achieve the bi-directional coupling analysis using ANSYS 12.0/ANSYS CFX 12.0.The purpose of this study is to clarify the effect of elastic deformation to vortex flow structure of elastic thin film.

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A number of studies on wake structures and the characteristics of dynamic thrusts of an unsteady airfoil have been reported over the years. However, behaviors of vortices that form wake structures and processes from generation to development have not been clarified. The authors measured vortex flow in the vicinity of a wall by PIV measurements and clarified the growth and development of vortices generated in the vicinity of the wall of heaving elastic flat plate quantitatively. We clarified that vorticities of vortex generated in the vicinity of a wall of trailing edge of elastic flat plate increase rapidly when the acceleration of heaving motion becomes maximum value. Moreover, vorticities of vortex generated in the vicinity of a wall grows up until the acceleration of trailing edge becomes maximum value.

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It is known that insects and aquatic animals fly or swim effectively by skillfully controlling their wings elastically deforming and vortices generated around a body. A flow field around an elastic body is treated as a coupled problem of fluids and structures (Fluid Structure Interaction Problem, FSI) and a series of phenomena, motion, structural deformation and generation / growth / development of vortices, are repeated continuously. However, impacts of elasticity on a flow field and dynamic forces have not been clarified yet. The purpose of the present study is to clarify the effect of the Young's module and airfoil configuration of the elastic flat plate by numerical simulation using ANSYS-ANSYS-CFX.

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Active control of flow separation was conducted with active vortex generator and micro flow sensor. The sensor can detect the momentum transport. Since the static characteristics of the sensor output has the near wall velocity corresponding to an extremum, it is possible to implement the maximization of the transport by using so-called extremum seeking and slope-seeking control. The input of the plant in the control system is an angle of attack of vortex generator and the output is the sensor output. As a result of applying the system to flow separation upstream of fence in the turbulent boundary layer, we confirmed the effectiveness of the system including the dynamic response.

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An active dimple with oscillating bottom surface was developed for flow separation control. It can provide a periodic disturbance into the flow by means of piezoelectric element. In this study, the basic characteristics of the active dimple are obtained by measuring the induced flow around dimple using dynamic PIV. The dimple diameter is 5 mm and Reynolds number of the cross flow based on the channel height is 650. The induced flow of solid dimple indicates the maximum value with the dimple depth of 0.5mm. It is found that the active dimple causes stronger induced flow than that in the solid dimple. Moreover, frequency of the induced flow from the active dimple can be easily controlled.

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A periodically separating flow is artificially generated on a flat plate and an attempt to control the flow by adding a feedback loop beneath the plate is carried out. The results show that the control device has a capability to suppress the periodical separation.

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An experimental study is performed for a channel flow over a backward facing step with the plasma actuator. The plasma actuator is an electric device designed for flow control using electrohydrodynamic effect. The plasma actuator is set at the step edge or bottom of the step. The Reynolds number based on the mean velocity at the inlet and the step height ranges from 800 to 3000. The wall static pressure and pressure loss coefficient are measured behind the backward-facing step.The result shows that driving plasma actuator at step edge is more effective than that at bottom of the step for loss reduction.

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In the present study, the flow over a backward-facing step has been investigated experimentally. The relative step height to boundary layer thickness of an incoming flow are H/δ_0 = 0.5, 1.0 and 1.5. Mean and fluctuating velocity distributions for H/δ_0 = 0.5 and 1.0 were examined by a stationary hot-wire and flying hot-wire anemometer with I-type probe. Streamwise distributions of the forward-flow fraction, γ near the wall were calculated, and then reattachment points of the separating flow were evaluated as a location of γ= 50%. In the range of H/δ_0 = 0.5 to 1.5 in the present study, the reattachment length is almost constant.

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To specify the effect of upstream pressure gradient on the mean velocity profiles of a separating flow, Couette type foward-facing step flow, whose upstream flow is the fully developed plane channel flow between moving and stationary walls, is investigated. The stationary wall has a step and the resultant channel contraction ratio (CR) is 0.75. The upstream flow is set as pure Couette (β_0 = 0) or pure Poiseuille (β_0 = -1)turbulence channel flow, where β_0 is the upstream flow type parameter. The upstream Reynolds numbers based on the friction velocity and upstream channel half width are about 300. Velocity profiles are measured with hot-wire anemometry at sections of x/H = -30,10,20,30 and 50. The distributions of pressure coefficient shows that the upstream flow is the Couette flow with negligible streamwise pressure gradient. The downstream mean velocity distributions of Couette and Poiseuille type flows reflect the continuity amstraint. Turbulemce instensity distributions show the effect of different flow type parameter.

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Recently, environmentally friendly nano-hydraulic turbine has much attentions, it is because that this turbine can be made at lower cost than traditional large plants, and be utilized extreme low head hydro energy effectively for local production and local consumption of electricity. In addition, this turbine can be placed without any civil engineering works, that is, environmental burdens are negligible. The authors have been focused on this type turbine, and developed several types to match the flow types, effective head and flow rate. This paper describes the development and demonstration status of these turbines, Savonius runner, waterfall type runner, undershot runner and jet turbine.

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An experimental study has been made on recovery process of the fully developed pipe flow disturbed by surface roughness. Two types of roughness were employed as disturbance, namely, k-type and d-type roughness. After disturbance of certain roughness pipe, mean velocity and Reynolds stresses were measured and discussion was made to response to the roughness and fundamental turbulent structure in the recovery process of turbulent pipe flow.

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The promotion of jet-stream diffusion may enhance the efficiency of mechanical performance in various industrial devices such as fluid machinery and combustion equipments. Both active and passive means were applied for the control of jet streams. Our previous studies disclosed that diamond-shaped cylinder bundles produce a self-excited oscillating jet-stream flow field having multiple uniform flow-rate groups. The present visualization work deals with effects of wall concavity on flip-flop flows in a diamond-shaped cylinder bundle. It is disclosed in the efflux jet streak-lines that characteristics of flip-flop flows are different in cases of the diamond-shaped cylinder bundle without and with wall concavity, respectively.

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Mean velocity and turbulent intensity measurements have been made for the turbulent boundary layer developed over two-dimensional square rib rough surface with longitudinal micro-grooves. The measurement was performed under a zero pressure gradient and momentum thickness Reynolds number of 8200. The velocity components were measured with a single hot wire probe and a constant temperature anemometer. The mean velocity and turbulent intensity close to the rough surface increase in comparison with those of two-dimensional rough surface. Then, the integral length is about 1.2 times of that the two-dimensional rough surface. As the result, it is expected that an error in origin has a large value compared with that of the two-dimensional rough surface.

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This paper treats the real-time sensing-based risk-mitigation control of hydrogen jet leakage in a partially open space with low openings by forced ventilation. After describing the computational geometry and scenarios, and the mathematical model and numerical procedure, we propose a partially open space that is robust to external environment. Related to this model, a risk-mitigation control algorithm to change the exhaust volume rate based on the least-square method for hydrogen sensor signals is proposed considering the results of applying various exhaust volume rates to the dispersion fields. The proposed method is validated against representative cases.

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This paper deals with characteristics of momentum added by a DBD Plasma actuator (PA) in uniform flow. The PA on a thin flat plate was located in uniform flow and velocity profiles in wakes of the PA was measured using a hot-wire anemometer. We investigated the momentum in flow filed added by PA, when velocity in the uniform flow was changed and voltage and frequency of input supplied to the PA were constant. As a result, the increase of the momentum is maximum value, when the induced velocity by PA (1.4m/s) is equal to the uniform flow velocity. In this case, the increasing rate of momentum was approximately 50%. On the other hand, if the difference to uniform flow velocity (6.0m/s) was large, the increasing rate of momentum was about 1%.

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High-Schmidt-number scalar mixing layers in the multiscale grid generated turbulence are experimentally investigated in a water channel by means of planar laser induced fluorescence (PLIF) technique and particle image velocimetry (PIV). The Reynolds number based on the effective mesh size and mean velocity is 2,500. Fluorescent dye (Rhodamine B; Schmidt number is about 2,100) is homogeneously premixed only in the upper stream, and therefore, the scalar mixing layer with an initial step profile develops downstream of the grid. Various turbulence quantities are evaluated and discussed.

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The effect of the shapes of the inlet and outlet pipes on the displacement efficiency of old water in a cylindrical water supply tank was investigated. The flow structure in the tank was also visualized with a planar laser-induced-fluorescence (LIF) technique. The inlet water jet was marked with a laser-fluorescent dye, i.e., a fluorescent yellowish-green (aqueous solution of disodium fluorescence). The displacement efficiency of water inside the tank that has an inlet pipe with a diverging nozzle and an outlet pipe with a circular baffle plate is better than that of the other tank. The decrease in the displacement efficiency of old water in a tank that has inlet and outlet pipes the center of the tank without a diverging nozzle and a baffle plate is related to the large fluctuation of flow near the outlet pipe. The baffle plate is found to prevent the diffusion of old water. The displacement efficiency of old water which is different in temperature to new water in the tank is not better than that of the same temperature. The cause of the decrease in the displacement efficiency is the stay of old wtaer near the center of tank.

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