NHK (Japan Broadcasting Corporation) plans to televise Yae Neesima's story for a year, inspired by the fact she wasborn in Fukushima, an area of Japan particularly hard-hit after the March 11 earthquake. She is the wife of DoshishaUniversity founder Joseph Hardy Neesima and one of the first Protestant women in Japan, as well as decorated warnurse. I will describe her life as the "brave story of a pioneer."

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The supercomputer "K" is now in service. We have been developing the software for this supercomputer, aimingat the medical application of predicting diseases, assisting the treatment or designing the new medical devices. Someof the software programs show excellent performance of massively parallel computing and are now open for thepublic use. In this talk, these programs are explained with the future direction of the development.

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Existing systems using field PIV or high frequency radar to measure surface velocity over a certain area shows apromising possibility to construct real-time monitoring systems of depth-scale flows based on surface velocity. In thisscenario, we propose Proper Orthogonal Decomposition-based Unscented Kalman Filtering, namely POD-UKF, asthe first step toward constructing such systems. Radial Basis Function is used as state-space models of POD-UKF.Measurement models are POD-based regression models using Kernel Ridge Regression. Data used in this work is1600 velocity snapshots of simulated flow over a Backward-Facing Step in an open channel. Estimation results areshown for tracking flow information at some subsurface regions based on "virtual sensors" of surface velocity.

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A synthetic jet array which can be actuated individually with different injection velocities is employed as an actuatorfor a control of flow separation. In the present study, the effect of different injection velocity of the jet array fromthose of adjacent jets on transverse vortex structure in the low Reynolds number flow over a backward facing step isdiscussed. The transverse vortex is generated from separating shear layer by applying synthetic jets to backwardfacing step flow. Measurement of wall shear stress by micro flow sensor and flow visualization were conducted onsapanwise and streamwise direction. The results show that different injection velocity in jet array induces differenceof propagation velocity of transverse vortices and distorted vortex structure.

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In the present study, the flow over a backward-facing step has been investigated experimentally. The relative stepheight to boundary layer thickness of an incoming flow are H/δ_0 = 0.63, and the momentum thickness Reynoldsnumber is 3000. Mean and fluctuating velocity distributions were measured by the flying hot-wire technique with Itypesingle probe and multiple probe rake, respectively. Proper orthogonal decomposition was employed to analyzespatial structures behind the step. Distributions of eigenvector and POD spectra were calculated, and joint probabilitydensity function and cross correlation coefficient between the POD coefficients of the first and second mode.

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Wavy-fin is used in the heat exchanger of the fuel cell for the characteristic of low-pressureresistance. Also, it has a problem that the fur forms in the wavy channel because of thefuel cell used water-cooling. Wavy-fin should not be clog. But,wavy-fin decrease thermalhydraulicperformance relative to off-set fin. Therefore, the purpose of this research isto increase the heat transfer of the put in the rectangular object in channel with wallwaviness. The influence of the vortex structure are delineated, along with an evaluationof the enhanced thermal-hydraulic performance, c is put into place the span directionand axial flow direction in wavy channel. Result of the numerical analysis, it can be seenthe vortex generation of promotion of flow mixing and increased momentum transportincrease as with decreasing the pressure resistance.

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The aim of the present research is to develop the fundamental study on the control of the self-excited oscillations indiamond-shaped cylinder bundles. The PIV measurements are performed on the flow visualization in the horizontal crosssection of the exit jet-stream flow field exiting from diamond-shaped cylinder bundles. Comparison is carried out using themeasured results in the absence or presence of the concavities constructed on both sidewalls inside the diamond-shapedcylinder bundle. It is found from the study that a substantial enhancement of |dV/dy| takes place at Type D60c for thestreamwise diverging diamond-shaped bundle.

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The dependence of the scalar derivative statistics on the Schmidt number is investigated experimentally in a liquid axisymmetric jet. Theconcentration of a commercial dye is chosen as a high Schmidt number scalar and temperature is chosen as a low one in this experiment. TheSchmidt number of the diffusing matter is 3,800 and the Prandtl number of temperature is 7. Instantaneous concentration and temperature aremeasured by using a fiber-optic concentration sensor and a cold-film probe, respectively. The measurement results show that the derivativeskewness of scalar decreases and its derivative flatness increases proportional to the turbulent Reynolds number R_λ. In addition, it is alsofound that the derivative skewness of scalar decreases with the increasing of Schmidt number and its derivative flatness is seems to beindependent of Schmidt number.

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The present study is designed to experimentally investigate the flow field past a rotary oscillating circular-cylinder in a uniform stream. Experiments were conducted with Re_d = 800 at the rotational speed ratio of 2 and the frequency normalized by a natural vortex shedding frequency in the range of 0.7 to 2.5. Instantaneous velocity fields were acquired with a particle image velocimetiy (PIV), and analyzed using an ensemble-averaging technique. The intensity of vortices discharged into the wakes and the spatiotemporal spacing of the vortex street were examined.

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It is important to understand and control wake structure behind three dimensional bluff bodies. The purpose of this study is to investigate the wake structures behind a circular disk and that excited by flow disturbance. Dielectric barrier discharge (DBD) plasma actuator placed on the side surface of the circular disk was used to generate flow disturbance. In Reynolds number of 5,000 and 10,000, mean velocities of streamwise, circumferential and radial direction are measured by X-type hot wire probe. Excited wake structure behind a circular disk was educed from these three velocity components.

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The purpose of the present study is to reveal the mechanism of amplified drag by flow acceleration. By using a multi-fan wind tunnel, we produced two kinds of unsteady flow. First, we performed experiments using rapid accelerations. fter the acceleration, a transient drag larger than the steady drag appeared for any case. Next, we performed another experiment using a sinusoidally pulsating flows with different frequencies. Comparing theoretical and experimental values, the added mass coefficient and the Basset-history coefficient were obtained by Odar's method. Using this one-dimensional formula, theoretical drags due to a rapid acceleration were obtained, and were compared with measurements.

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Turbulence generated through 3 dimensional Fractal structure object was investigated.Four variations of the Sierpinski tetrahedra were chosen to examine the effect of lacunarity,arrangement and number of iteration on the turbulence decay. Turbulence generated by all structures decays with power law after initial development. However, the original Sierpinski tetrahedron and the one with different lacunarity showed exponential decay and accelerate the decay in the farther downstream.

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Jets generated in the flow past a sphere moving vertically at constant speeds in a saltstratified fluid are observed by laser-induced fluorescence(LIF). In previous shadowgraph experiments, the jets are classified into seven types. In this study, density distributions in the vertical plane are observed when a thin jet or a broad jet is generated. It is confirmed experimentally that when the stratification is weaker and a broad jet is generated, density boundary layer is thicker than the case when the stratification is stronger and a thin jet is generated.

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The purpose of this study is to understand the overshooting phenomena during vortex formation in the wake of a flat plate. The vortex formation process on the overshoot was shown by using the phase average technique. As the result,it was found that the vorticity at the center of a vortex increases in the downstream direction during the overshoot.

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Turbulence generated through the Sierpinski tetrahedra was investigated. The Sierpinski tetrahedron is a model of foliage distribution of crown tree, and fractal dimesion of both strucures is two. Velocity ditribution in the cross section corresponds to the arrangement of the smallest tetraheda. Skewness of velocity fluctuation is positive in the lower speed region and vice versa, while flatness lies between 2.8 and 3.0 across the section. Taylor microscale based Reynolds number obtained was much greater than the corresponding grid generated turbulence. And the inertial subrange was observed.

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The flow around a rectangular cylinder which moves over a plate has been simulated by the LES method at Reynolds number of 7,000. The Smagorinsky model was used as a subgrid scale (SGS) model. The time averaged and fluctuating fluid forces were calculated by changing the gap-to-height ratio S/H and the width-to-height ratio B/H of a cross section of the rectangular cylinder, as parameters. The lift force variations from the numerical analysis are in good agreement with those of the experimental data from the towing water tank tests. For S/H ≦ 0.5, the drag forces are not dependent on the width-to-height ratio B/H. It is found that the lift force variations to the gap-to-height ratio S/H relate with the flow pattern of three dimensional vortex structures.

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In the present study, we investigate a self-excited oscillatory phenomenon of a two-dimensional confined jet with a rectangular-cross-section cylinder as a downstream target. More specifically, we conduct experiments and numerical simulation. In computations, the numerical method adopted here is a finite difference method (FDM) formulated in terms of vorticity and stream function. The governing equations consist of a vorticity-transport equation and a Poisson equation of stream function. To specify the value of stream function on the target surface, the condition of single-valuedness of pressure are applied. As a result, we confirm a good agreement between experiments and computations, which suggest that the concerning phenomenon is intrinsically two-dimenssional.

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Large-eddy simulations are performed for hyperbolic stagnation-point flow driven by steady external body force in the form of quadruple vortices. Transition from a steady state to a turbulent state is observed in this flow system, and in the transition path stable periodic motion is found. This periodic motion is characterized in terms of the dynamics of two classes of vortical structures, one of which is the quadruple vortices sustained by the steady body force, and the other is smaller vortex tubes. The smaller tubes are stretched to be intensified in the stagnation-point flow induced by the quadruple vortices. This intesification process is reminiscent of the stretching of smaller vortices between anti-parallel vortices, leading to the energy cascade in isotropic turbulence (Goto 2008,2012).

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Subcritical transition to turbulence in wall-bounded shear flow is known to be characterized in terms of turbulent patches bounded by laminar regions. In this study spatially localized turbulence structures are investigated in rectangular-duct flow of cross-sectional aspect ratios A_S = 1 - 9 at marginal Reynolds number Ret. The lowest Reynolds number Ret for transient turbulence is determined to demonstrate its dependence on the aspect ratio As. It is found that Ret monotonically decreases from Ret = 730 for As = 1 with increasing As, and for As = 5 it nearly attains to a minimal value Re_T ≒ 670 which is consistent with the Reynolds number for the appearance of a turbulent puff in a plane channel (As = ∞). Streamwise-localized (turbulent puff), or streamwise- and spanwiselocalized (turbulent spot) turbulence are observed at the Reynolds numbers Re = Re_T for distinct As. The localized turbulence exhibits structural 'transition' between a turbulent puff and a turbulent spot around As = 4.

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The transition to turbulence of the flow in a straight pipe is numerically studied over a range of Reynolds number where turbulence begins to expand by puff splitting. Puff splitting presents itself as a stochastic two-step process. A splitting puff first emits a kind of chaotic pseudopod made of azimuthally localized streaky structures at the downstream (leading) laminar-turbulent interface. This structure then expands azimuthally as it detaches from the parent puff. Detachment results from a collapse of turbulence over the whole section of the tube. Once the process is achieved a new puff is born ahead.

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Turbulent structure in a boundary layer developed over two different types of three-dimensional rough walls, namely, cavity and protrusion has been investigated to understand effect of the geometrical feature on turbulent statistics. Experiments were made under the zero pressure gradients with constant free stream velocity of 7m/s. Over the protrusion type of rough wall, the local skin friction coefficient Cf is much larger than those of d-type and cavity type rough wall flows. As R_θ increases, the local skin friction coefficient tends to almost the same value over d-type and cavity type rough walls. Deficit in mean velocity profile is the largest over the protrusion type and takes almost the same over the cavity and d-type rough walls. Certain differences corresponding to the geometrical feature are observed near wall and around outer edge of boundary layer in skewness profile of S(ν)

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Response of the fully developed turbulent pipe flow has been investigated to sudden change of wall condition from smooth to rough. Experimental study of mean and turbulent quantities focuses on recovery process and distance required to reach to new equilibrium state. The inner diameter and total length of the pipe flow equipment are D=70[mm] and L=12[m] (=17 ID), respectively. Ak-type roughness composed of array of square bars is employed as rough wall and velocity measurement was made by a constant temperature anemometer and a single-hot wire probe. Derivative of wall static pressure with respect to the longitudinal direction takes the minimum value at x/D=15 and then approaches asymptotically to constant for jc/D=40〜50. The mean velocity and turbulent intensity profiles suggest that the internal boundary layer reaches to the pipe center at around x/D=15.

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Wind tunnels are useful tools when we investigate the aerodynamics characteristics of scaled models of (i) runners of track-and-field athletics and marathon, (ii) land vehicles such as trains and cars and (iii) creatures like flying fishes. In wind-tunnel experiments which are the most effective approaches to such studies, a moving-belt system is indispensable for precise aerodynamic measurements considering the ground effect. In the present study, we develop a moving-belt system for fundamental and accurate wind-tunnel experiments concerning the ground effect, and show its basic performance such as the profiles of time-mean flow velocity and turbulence intensity above the moving belt of the system using a hot-wire anemometer. And in order to show the effectivity of the moving-belt system, we put in the thin flat plate above the moving-belt and run visualization and flow analysis to find out ground effect by using moving-belt.

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Applicability of law of the wall to turbulent boundary layers under favorable pressure gradient has been studied using direct measurement of the wall shear stress. The effect of lip pressure that would produce extra force acting on a floating element of the direct measurement has been investigated for improving reliability of measured wall shear stress. The experimental results suggest that the lip pressure is unable to be ignored in the direct measurement. The logarithmic mean velocity profile using friction velocity determined by the direct measurement is disagreed with the standard log-law. The favorable pressure gradient reduces magnitude of the streamwise turbulent intensity normalized with the friction velocity compared with that of zero pressure gradient.

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Direct flow drag measurement device for obstacles placed in the boundary layer has been developed and effect of angle of attack for drag acting on the pyramid has been investigated experimentally. Reliability of the developed measurement device was confirmed with a corn which drag force can be obtained by wall static pressure measurement. Apex angel of the pyramid is 2_α=60° and ratio between the height of the pyramid and the boundary layer thickness is δ/h≒0.52. Flow drag was measured at various angle of attack γ for the pyramid. Drag coefficient takes the maximum value near γ=0° and almost constant at |y|≧15°. Variation of the drag coefficient for angle of attach has abrupt change at |γ|=3°.

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In the present paper in order to investigate the possibility of flow control using elastic body, we conduct a simulation of a finite-length square cylinder placed inside turbulent channel flow. For an elastic cylinder, the rigorous equation of motion for elastic continuum is solved with a finite volume method; the effect of existence of cylinder in the flow computation is taken into account using the immersed boundary method. From time averaged quantities, we demonstrate that the flow pattern around rigid cylinder is in accordance with that of previous reported experimental results and that the elastic cylinder markedly modulates the wake structure, u

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The smoke dispersion of a buoyancy jet was investigated in a cross flow in a wind tunnel with a Makita-type active turbulence grid. These smoke structures in the downstream field from a chimney can be divided into 6 types depended on buoyance force and momentum of the jet, turbulent motion of the cross flow, etc.

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It was attempted to control of jet diffusion of round jet using centripetal type plasma actuator. It was visualized and analyzed by the PIV. It was obtained the following. By driving a steady plasma actuator, the induced flow convergence, has become a jet of volume flow rate Q = 15 〜 50L/min. Induced flow which caused by the ionized area are concentric, the flow velocity becomes faster and boundary layer thickness becomes thicker, as ionized area larger. When applied to a circular jet, the velocity of primary jet becomes faster by the effect of contraction and the momentum of the induced flow. When the ionized area becomes narrower, the effect of contraction by the induced flow is increased.

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The purpose of this study is to clarify relations between flow structure and dissolved concentration transportation in a bubble column. We calculated the time-spatial scale of the bubble swarm, fluid body and dissolved concentration transportation based on the thinking of integral length scale, by using a newly developed Photoelectric Optical Fiber Probe (POFP) and LDV. The spatial scales of the bubble swarms and fluid bodies decreased toward the upper zone of the bubble column, and these scales varied with time. Furthermore the radial profiles at the horizontal sections differed in the height and time. We discussed the flow structure in the bubble column from these results. In addition, the spatial-scale of dissolved CO_2 concentration had the different characteristic by the height from the bottom of bubble column. Thus, the relations between the flow structure and dissolved concentration transportation were found out.

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Mass transfer from a bubble should be understood in consideration of a relationship between the bubble motion and the surrounding liquid motion. This paper focused on bubbles categorized into 2-3mm in diameter. The bubbles commonly show the highest mass transfer rate, zigzagging ascent motion, and periodical vortex shedding. The relationship between the mass transfer and the motions of the bubble or the surrounding liquid motion are not found, but it is essential. For the fulfillment of the objective, we conducted experiments of capturing the projection images of the bubble with two high-speed cameras. The change in the bubble volume was calculated from the captured images based on an original image analysis. The mass transfer was enhanced in certain sections in which the bubble was accelerated and vortices were shed. The mass transfer enhancement arose from the acceleration and vortex shedding.

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Motion and wake vortices of a rising bubble of Re =246 in a still liquid in a vertical pipe are studied experimentally using photochromic tracer and high-speed cinematography. Three velocity components of bubble measured by video image processing show that zig-zag motion of the bubble is dominated by lateral velocities. And the shedding of vortex loops behind a bubble correlates well with lateral motion and orientation of the bubble. A stereo display system was constructed by commercial stereo display and used to examine the complex three-dimensional vortices and dye patters in the bubble wake.

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An experimental study of the pulp suspension flow in a duct was performed. The duct, in which a partition plate with a tapered trailing edge was inserted, was a modeled hydraulic headbox of papermaking machines. Wakes formed downstream of the partition plate were investigated by the flow visualization, and also measurement of fiber concentration was executed. Moreover, the time-averaged and fluctuating fiber concentrations were obtained for various flow velocity. A discussion is given on the changes in the flow rate and in the fiber-concentration distribution along the duct axis. The characteristics of the pulp suspension flow were clarified.

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PIV measurement using micro bubbles (mean diameter 40-50μm) as tracers was attempted. Turbulent backward-facing step flow Was chosen for test case. Visualized flow image obtained by bubble tracers in our first trial was not sufficient for pattern matching in PIV process. Results show higher quality image is needed for complicated

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To improve rotation performance of vertical axis wind turbine, new blade profiles that can rotate turbine rotor in wide range of wind speed are proposed. This new blade starts-up rotation as drag-type rotor in low wind speed condition. In high wind speed condition it changes mounting angle 90 degrees and keeps rotation as lift-type rotor. Results obtained by numerical and experimental investigations suggested proposed new blade profiles have higher performance as compared with conventional blade profile.

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Two-dimensional wing (NACA6409 airfoil) was installed in a water tunnel to visualize flow separations from the top urface of the MAV's wing at an attack of angle and three kinds of low Reynolds number. The angle of attack was 20 degrees, and Reynolds numbers were 0.85x10^4, 1.14x10^4 and 1.43x10^4, respectively. The flow separation from the wing top surface was visualized by PIV, and it was observed that separations grew big whenever Reynolds number became bigger.

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Flying and aquatic animals release a vortex by pitching a wing or a fin. The behavior of this vortex affects unsteady fluid forces. The role of unsteadiness is critical in the generation of momentum and therefore in the force generation. That is, the unsteady forces must also be considered when estimating the propulsive force of swimming doing the front crawl. In the present study, the vortex structure and its behavior of a discoid airfoil simulating a swimmer's hand are investigated during pitch-oscillating motion in a wind tunnel test to elucidate the relationship between three- dimensional vortex structure and unsteady fluid forces. The vortex growth is observed during pitch-oscillating motion, and large scale vortex is released into the wake of the airfoil. Furthermore, the peak value of fluid force for the case of changing in speed during one pitch-oscillating motion becomes larger.

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A one-equation subgrid scale model is improved for the large eddy simulation of turbulent flows. It combines advantages of the one-equation dynamic model by Kajishima and coherent structure model by Kobayashi. The proposed model has been applied to low a Mach number turbulent flow around a two-dimensional airfoil with 9 degree angle of attack in a uniform stream. Computational results of the new model show almost the same and reasonable performance as the one-equation dynamic model with the significant computational cost reduction.

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In this study, the flow instabilities downstream of inlet guide vanes are investigated by conducting experiment and performing a numerical simulation. An attempt is made to clarify the influence of number of vanes on the flow patterns including cells formation and the exit flow angle. Furthermore, the propagating angular velocity ratio of the instability for various values of vane angle β_2 and number of vanes is presented as a function of exit flow angle α_3

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A flat plate wing was applied to flow management of stronger wall jet with constant velocity ratio of U_m/U_e=4. The normal straight flat plate and three-dimensional wing with notched trailing edge were employed and located at center of the outer layer in the jet with constant angle of attach of -4 degree. The two wings increase the maximum velocity and velocity in the outer layer. Turbulent intensity profile and Reynolds shear stress profile was decreased by flat plate wings. Streamwise mean momentum flux integrated in cross streamwise plane is increased by flat plate wings. The increasing rate of momentum flux is enhanced by the three-dimensional wing.

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The present study clarifies some thrust characteristics of synthetic jets by conducting numerical simulations. In this paper, two types of synthetic jet thrusters are proposed and the thrust of both are compared. It is found that the fluid force and the velocity distribution around a synthetic jet thruster depend on the non-dimensional stroke of the synthetic jet.

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The effect of the coherent structure on the pressure diffusion of the turbulent energy in a plane jet is investigated experimentally. The experiment is performed by the simultaneous multipoint measurement of two velocity components and static pressure with using the "combined probe", which consists of a probe for pressure measurement and an X-type hot-wire probe. The measured pressure and velocity data are analyzed by applying the Proper Orthogonal Decomposition (POD) and the coherent structure is specified. Further, the complementary technique of Linear Stochastic Estimation (LSE) is used to reconstruct the instantaneous pressure and velocity field of a dominant POD mode and discussed. The results show that the pressure diffusion process of the turbulent energy from outer side of the jet to the inner side is caused by the coherent vortex structure suggested in the previous studies. This means the coherent vortex structure near the jet centerline has an important role of the pressure diffusion process.

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For Shear Stress Transport (SST) turbulence model, an anisotropic algebraic constitutive relations for the Reynolds stress tensor are integrated in CFD solver developed in JAXA called FaST Aerodynamic Routines (FaSTAR) that is three-dimensional compressible Reynolds averaged Navier-Stokes code. Using these relations, we calculate computations of three-dimensional wall-jet. As compared with experimental data, it is found that a wide spreading in spanwise direction in cross section of jet axis can be predicted and the obtained ratio of velocity half-width is improved by taking into account the anisotropy. The obtained results of SST turbulence model with algebraic constitutive relations agree quite well with those obtained in experiment.

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Radial distribution of scalar statistics in a low Reynolds number turbulent round jet with high Schmidt number (Sc=2300) is investigated. Evolution of instantaneous scalar distribution is measured by the LIF method using line scan camera. Statistics up to the fourth order show good agreement with the previous researchers' results. The frequency spectra obtained from scalar timeseries exhibit the -1 power scaling.

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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 will use it for the jet diffusion control such as a low velocity burner flame. In this experiment, we examined the difference of the influence given to the primary jet when it changed the electrode sizes of the nozzle exit. Moreover, it measured when the voltage and the frequency of the power supply were changed. As a result, the diffusion effect of the jet flow was seen by the rise of the voltage and the frequency. The difference of the induced flow with the plasma by changing an electrode was measured.

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Experimental and numerical investigations of jet oscillation in a dual-bell at a low-altitude operation mode are carried out. At the low-altitude operation mode, a supersonic jet separates at an inflection point of the dual-bell nozzle. An axial mode and two diametrical mode of the jet oscillation occur. Up to now, the cause of the axial mode has not been clarified. Numerical simulations with flow excitation are carried out. It is confirmed that the jet oscillation occurs due to acoustic resonance. Additionally, interactions between the separated jet and a film cooling flow are investigated. The experimental and numerical result show that the film cooling flow excites the main jet oscillation at the low-altitude operation mode.

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