Positron emission tomography (PET) is a nuclear medicine technique using short-lived positron emitters such as 15O, 13N, 11C and 18F. PET can measure quantitatively tissue metabolism in living humans. Then, PET can be one of the best technique for the visualization of human brain function. Using PET, we can visualize and quantify blood flow, glucose (energy) metabolism and neuroreceptor binding of the human brain. For that purposes, 15O-labeled water, 18F-fluorodeoxyglucose and 11C or 18F-labeled receptor ligand are used. One of the applications of PET for brain research is a functional mapping of the human brain. Changes of cerebral blood flow is measured under physiological conditions or some sensory or behavioral task and then we can localize areas responsible for the specific function. As examples of this approach, motor control of hand movement and sensation and discrimination of salty taste will be introduced. As examples of neuroreceptor studies, visualization and quantification of dopamine receptor will be also introduced.
Since the concept of passive control of shock-boundary layer interaction using a double slot was published in 1984, several papers have been reported on the application of this technique to transonic airfoil flows. In the present paper, this technique is applied to condensation shock wave which is caused by rapid expansion of moist air in a supersonic nozzle. The effects of passive control on condensation shock wave have been experimentally investigated by a schlieren optical method and pressure measurements. As a result, it is found that the passive control is the useful technique to suppress the periodic oscillation of condensation shock wave.
In the super sonic flow through the cascade of a gas-turbine engine, flow separation and shock waves are important phenomena impacting the performance. This report describes an basic experiment to detect these phenomena using hot film sensors. In the super sonic wind tunnel test, flow separation or a shock wave is induced to occur on the surface of the cone-like model at Mach 2.5. Data are collected from hot film sensors located on the surface. Schlieren and oil flow visualization method are also applied to check the flow. As the results, the separation and the shock wave can be detected by the differences between the sensor output.
The self induced flow oscillation occurs when an underexpanded sonic or supersonic jet impinges on an obstacle. From the previous numerical analysis, it is shown that the existence of the secondary annular flow around the supersonic jet is effective to repress the self oscillation of the mach disk. The purpose of this study is to investigate the effect of the annular flow for repressing the flow oscillation. The flow visualization using the shadowgraph method is carried out and the experimental results are compared with the numerical calculation solved by the TVD method.
The interaction of a shock wave with a gas bubble was visualized by double exposure holographic interferometry or shadowgraph for four combinations of liquid/gas, such as, silicone-oil (1.0 cSt)/air, silicone-oil (10cSt)/air, water/air, and water/helium. The gas bubble was exposed to a spherical shock wave generated by detonating a 10 mg silver azide pellet. The gas bubble contracted by hitting of the shock, and aa liquid jet formed, as the case may be. Eventually, one or plural rebound shock waves occurred. It was found that there are at least three types of rebound shocks. The generation of these for each type is explained by sequential flow visualizations. Numerical simulations were also carried out using GRP/MIT scheme.
A holographic interferometric visualization of the reflection and diffraction of shock waves was conducted using a diaphragmless shock tube. The diaphragmless shock tube, using a rubber membrane to seal the high pressure and low presuure sections, enables to generate shock waves with much better repeatability than conventional shock tubes. The reflection of weak shock waves from wedges of various inclination angles was observed. The diffraction of a shock waves passing through a sharp 90° corner was also visualized. It is well demonstrated that the diaphragmless shock tube equipped with holographic interferometry is very effective for investigations of weak shock wave reflections and diffractions.
The paper presents a result of double exposure holographic interferometric observation of shock wave behavior in three-dimensional flow field. The present holographic interferometer used a double exposure of a few micro seconds time interval between first and second exposures. This was a qualitative optical visualization method, and enabled to clarify three-dimensional shock wave reflection over a corner consisting of vertical and horizontal wedges. A result of numerical simulation was compared with the present visualization.
The result of numerical simulation of shock wave diffraction around a 90° corner is visualized by VTR animation. The two-dimensional compressible Euler equation is solved by a finite-difference scheme with high resolution. An adaptive mesh refinement algorithm is adopted to achieve high resolution. The separated shear layer developing from the diffraction edge rolls up to discrete vortices by instability. In the case of Mach number greater than 1.5, these vortices are seen to interact with the secondary shock wave; a branching phenomena of shock wave is clearly observed.
A technique has been developed to measure surface heat transfer on windtunnel models in hypersonic flow based on the color response of encapsulated thermochromic liquid crystals. This method supplies data of a superior spatial resolution at experimental uncertainties comparable to traditional methods. In contrast to previous liquid crystal measuring techniques a calibration of the color-temperature response is performed during the actual experiment, thus avoiding inaccuracies originating from differences in the experimental setup. The method is automated to allow the efficient collection of experimental data. Results are shown for experiments performed in a Mach 5 blow-down windtunnel and compared to' thermocouple measurements.
Hypersonic liquid jets were generated using a single-stage powder gun. The jets and shock waves were visualized using a double exposure holographic interferometry. In the injection of diesel fuel, self-ignition and combustion were found.
Cross-correlation function used in the binary image cross-correlation method developed by Uemura, T., Yamamoto, F., and Koukawa, M. is used without mathematical strict proof, although their method is thought to be convenient and efficient to analyze the particle images due to the high speed algorithm for particle identification. In the present study, the binary image crosscorrelation function is derived from mathematical foundations, and the generality is discussed. Since the velocity vectors are computed discretely at the particle positions, some interpolation methods are needed to rearrange the velocity vectors at the grid points in order to extract the other physical informations. The three following new mathematical interpolation methods (differential form of equation of continuity, integral form of equation of continuity, and boundary element method) are proposed in the present paper.
The flow characteristics of two models of cross flow fan were clarified by the flow visualization and LDV investigations. The velocity vector maps, stream lines and vorticity distributions were obtained so that the position of the eccentric vortex in the rotor was clear. Furthermore, the aerodynamic characteristics of a blade and the power generated by a blade were clarified. The results showed that the blades of rotor at 8=240° to 270° (in discharge area) have a good aerodynamic performance and have done the much work than that of the suction area. The effect of changing of casing's shape and suction load in suction area on the flow pattern was also cleared.
The blade shape design is one of the most important factor for improvement of efficiency or noise reduction of a centrifugal fan. However, it is not easy to analyze flow through impeller blades both theoretically and experimentally. This paper describes an experimental investigation of flow through impeller blades of a fundamental model of the centrifugal fan and a multi-blade fan by means of quantitative method of visualization. The results obtained show the instantaneous profiles of flow through blades.
Coherent structure in fluid dynamics has been the subject of much reseach in resent years and substantially affect the development of technology. In this study, we attempt to investigate two-dimensional coherent structure using flow visualization and color image analysis. Here, coherent structure is originated mixing flow in the water channel and visualized to use some color dyes. Flow field of color regions is changed markedly and recorded by camera or video camera. Thereafter, we analyzed these pictures using personal computer. With the aid of color image analysis, it can be obitained physical quantites from visualization pictures. For example, it is measured each color area, fractal dimension and so on.
Visualization study of the behavior of lubricating oil film between rotating wet clutch disks used in automatic transmissions, taking account of the porous facing of one disk, was conducted by a high speed video camera when the plates were engaging. Pressure on porous surface of the plate, friction torque acted between disks, and rotating speed of the reaction plate were measured simultaneously with the visual recording. It was found that air bubbles became visible on surface of porous plate during the boundary lubrication stage. The variation of surface pressure had a strongly effect on the behavior of air bubbles.
Turbulent transition problem of three-dimensional (3-D) boundary layers become one of the major research topics in fluid dynamics field, because of further refinement of general fluid machineries. Especially, investigation of the boundary-layer transition over a swept wing is important in order to increase commercial aircraft fuel efficiency. However, turbulent transition process in 3-D boundary layers are not well understood. Purpose of the present investigation is therefore, to clarify the transition process through visualization in the case of rotating axisymmetric bodies in general. Results shows that streamwise vortices appear in advance to T-S wave instability, and appearing instability is influenced by the local flow condition where transition appears, and centrifugal or crossflow instability might appear.
Classification of the particles can be achieved by the active control of the suction velocity of a sand collector. In this paper, flow visualization of the classifying region was carried out by changing the injection velocity kept the suction velocity constant. The width of suction slit 100mm is used and the width of injection slit is varied to change the injection velocity. Only the smaller beads are collected from the mixed particles bed which consists of combination of the larger beads (not collected) and the smaller beads (collected). From the results of analyzing the visualized image of the classifying region, the effects of the injection velocity on the classifying volume and classifing time are discussed quantitatively.
To visualize the 3-dimensional motion history of a particle, an analysis method has been developed for streak holography. Analysis method is based on the fact that inline hologram of a particle has circular fringe pattern that can be calculated either Mie scattering theory, or Fraunhofer or Fresnel diffraction theory. The image analysis can be simplified at discrete times when fringe is just tangent to the camera slit. This method is successfully applied to one of particle streak hologram to obtain 3-dimensional trajectory of it. The results of these examinations suggest the feasibility of streak holography for the visualization of particle field such as aerosol transport, combustion, multi-phase flow, etc.
A new image analysis method is presented of determining the size and position of particles by in-line holographic technique. The method is based on the mesurement of diameter of circuler fringes of the in-litre hologram of a particle, which is considered to be almost independent on the photographic conditions and films. The method is based also on the detailed calculation of the in-line hologram pattern of a particle by the Fresnel diffraction theory. It is found that fringe diameter divided square root of particle distance is a slowly varying function of far-field number. The order of fringes have been identified by comparing the hologram with the theoretical prediction, then the far-field number can be estimated in a precision of±1. This approximate far-field number can be used to determine the particle position precisely from the measured fringe diameter of the identified order.Precision of the obtained particle coordinate has been examined by a different dual in-line hologram method proposed by us. Particle diameter can also be estimated successfully by applying Silverman et al's method with the accurate value of particle coordinate.
Double flash photographs of liquid atomization process by color CCD camera was used for velocity measurement. The intensities of blue image and green image are reversed, and their cross correlation coefficients are calculated by using fast Fourier transfer. Then, the displacement of those images is obtained, and 2-dimensional velocity is measured. Velocities of droplets or liquid sheets with complex shape were measured well. But the peaks of cross correlation coefficients for liquid sheets image are not so clear as those for droplets image. Velocities of liquid jet surface wave could not be measured well, but enforcing the boundaries between liquid and air using differential processing enables the velocity masurement.
Flow pattern on flooding phenomena in counter-current two phase flow in vertical tube is experimentally studied by means of dye tracer technique for the following conditions: the length-to-diameter ratio L/D=30. Just before flooding, oscillatory motion of the liquid upwards and downwards in the tube is observed. Under flooding conditions, churn flow in the tube is observed.
Bragg scattering occurs when the wave length and the angle of incidence and the distance between the rows of piles satisfy the Bragg's law, and the scattering waves become stronger. When the incident lights travel to the water surface they refract at this water surface, and the refracted lights travel in the water. Then the lights meet together under the crest, not so much under the trough, so these lights make the brightness distribution at the observation plane in the water. We visualize the scattering waves by measuring the brightness at the glass plate in the water.
At the sunroof opening, the vortex formation will occur in the boundary plane where inner and outer flow will meet. These vorticies are transfered toward downstream and run into the rear opening edge. The pressure fluctuation by this collision sometimes causes the wind throb in the compartment. In this paper, such a phenomenon is visualized numerically by CFD technique in the three dimensional domain. The relation between vorticity distribution, frequency analysis of pressure fluctuation at the sunroof opening and wind throb is described. The effect of flow deflector which improves the flow pattern around the sunroof opening is also shown and discussed.
An experiment of wave making using ferrofluid was carried out. The visualized wave pattern shows that the the angle between the wave crest line and the rail center is larger as the gradient of the magnetic field increases. It is possible to change Froude number even with same model size and also with same speed by controlling the gradient of magnetic field in ferrofluid.
Many apples dropped by a Typhoon 9119 in Aomori Prefecture, and farmars sustained great damege. The state of fruit drops are regional differences, therefor it is considered that the flow of wind is influenced by the cinfiguration of the ground. The flow patterns on the relief model of Aomori Prefecture are visualized by a smoke-wire method, and the scale of eddy and the period of vortex shedding in behind the Mt. Iwaki have been obtained from it.
On July 12, 1993 an earthquake occurred off the southwestem coast of Hokkaido and generated a giant tsunami. Just after the earthquake, Harvard University obtained a model of a fault plane, estimated from the seismic wave analysis. However, this model can not explain well the corresponding tsunami. On taking the measured tsunami runup distribution into consideration, the authors arrived at a solution, DCRC-17a, which consists of three fault planes. The DCRC-17a explains very well runups as well as the measured ground subsidence in Okushiri Island. Both of the computed results for the Harvard solution and DCRC-17a are compared in a CG animation, which shows well the dynamic movement and the generation of complicated patterns at and around of Okushiri Island and between Okushiri Island and Hokkaido.
It was difficult to visualize large scale oceanic and atmospheric phenomsna because of limitation of the observational ability. The satellite remotesensing provides various types of the earth observation data. Using the satellite data, several oceanic and atmospheric phenomena around Japan were captured in the satellite images and visualized.
A new flow visualization system using a infrared laser sheet was developed. The system is extremely inexpensive and very easy to handle comparing with a ordinary laser sheet. The flow patter around a low-rise building is visualized by the system. Horse-shoe vortices in front of the building, rolling up process of a separated shear layer and conical vortices on the roof are clearly seen by the system.
Further investigation on a practical applications of the Karman vortex flow meter were studied. In this experiments, the effects of a distance between two parallel side plates of a Karman vortex shedding from cylinders with three shapes of cross-sections were investigated. The three types of cross-section were (1) circular type, (2) semi-circular type and (3) semicircular with plate which is effective to stabilize the vortex shedding. Within the limits of this experiment, the shedding frequency of the vortex were reduced by the groth of the boundary layers of each side plate, and a characteristic flow patterns were observed by the flow visualizations.
When an orifice tube oscillates vertically in water, vortex rings develop through expulsion of water from the orifice both above and below the orifice plate. If the input condition to vibrate the orifice tube is specified, the time-mean flow going away from the orifice plate in one direction is induced during one period because the quantity of the water, which is entrained into the vortex ring from the surface of the orifice plate and the surroundings and is transported with it, is different between above and below side of the plate. This paper describes the behavior of the vortex rings visualized with the tracer method and also gives a brief summary of the experimental study to apply the above mentioned phenomena of the vortex ring to a vibration pump.
The vortx shedding from a circular cylinder in oscillatory flow in a pipe is visualized by smoke-wire method. It has been observed that patterns of vortex shedding varies with the oscillatory amplitude under a constant Reynolds number and oscillation frequency. Two characteristic flow patterns are observed; one is that two symmetric vortices are shed simultaneously during one period of the flow oscillation, and the other is that two symmetric vortices and single one are shed alternately.
Vortex chamber Oscillation Device is a Fluidic Watering device of a simple structure without any moving part, and to which only self-oscillating phenomena of water is applied. To visualize this oscillating phenomena, the high speed camera, 4000 frames per second, is applied and the instantaneous images are taken. Using these continuous images, the oscillating frequency was estimated; and the wave shapes of oscillation were obtained by the output of the small pressure tranceducer which is placed facing to the outlet flow near outlet port. The flow pattern was made clear by the computer simulation, and the necessary data to improve the characteristics of this device were obtained by this computational results. This device is used effectively for snow melting installation of Shinkansen, the washing machine of food case and machine element, and the hygienic washer.
The X-shaped intersecting ducts have a structural defect in engineering because of extra ducts at both the confluent and branching sides. However, the results are interesting when researchers apply the characteristics of flow around the intersecting region with the use of newly developed apparatuses. Experiments are performed to investigate the flow rates around the intersecting region by changing the condition of upper water levels. It is found that the Coanda effect occurs in the flow of the intersecting ducts. It is also disclosed that the flow rates in the intersecting ducts become greater under the influence of suction in the upper duct during which the water is cut off from the supply.
Flow visualizations of the flow pattern in several logarithmic spiral curved diffusers were caried out in order to clarify their characteristics and to improve their performances. In this study, the effects of the difference in the logarithmic spiral angle of the curved diffuser on the flow patterns are clarified by the flow visualization with smoke wire method using High Speed Video Camera, and the diffuser performance is clarified. And, their results are compared with the pressure distributions along both diffuser walls, the velocity and vector distributions in diffuser channel. As the results, it was found that the flow patterns obtained by the flow visualization were very useful to prove the data obtained by the wind tunnel experiment and the performance of the curved diffuser was affected considerably by the logarithmic spiral angle.
In this study, the effects of the variation in the logarithmic spiral angle of the curved diffuser on the flow pattern are clarified by the flow visualization, and their results are compared with the numerical solutions obtaind by the finite element method. And the difference of flow patterns between the open channel and the closed channel is clarified. As the results, it was found that the flow patterns using closed channel by the flow visualization agreed comparatively with numerical results, and the performance of the curved diffuser was affected considerably by the logarithmic spiral angle, especially, the flow pattern indicated the desirable value, when the spiral angle β was in the region of about from 20° to 25°.
The flow pattern of viscoelastic fluid through a divergent pipe hasn't been clarify at the present time. The purpose of this study is to clarify the flow pattern of a non-Newtonian fluid through a divergent pipe. In this paper, as a basic study, the effects of the variation in the divergent angle of the pipe and the Reynolds number on the flow pattern of water through a divergent pipe are clarified by means of the flow visualization using Tellurium method and the numerical calculation using the COSMOS/M. As a result, it was found that a certain degree of coincidence was obtained between the flow visualization and the calculation, and the flow pattern was affected considerably by the divergent angle of the pipe and the Reynolds number. Furthermore, in this experiment it was found that the flow pattern indicated the more desirable results with the divergent angle 2θ=10°.
By visualizing the flow at the outlet cross section of the diffusers having the total divergence angle of 8° by tuft grid method, the flow patterns were examined. Due to the separated flow from the wall surface and corner parts, reverse flow occurred at the outlet cross section. With visualizing the near wall surface flow and the corner parts flow by tuft stick method, smoke tracer method and polystyrene tracer method, reverse flow patterns were examined. It was found that the revfrse flow were existent from outlet section to Inlet section at cornet section of regular pyramid diffuser.
The wire deformation and the inference of viscosity of mold resin within the cavity of a transfer molding process were studied with flow visualization experiments and image processing measurements. Through experiment by using real resin, the measurement method has been proved to be useful for improving this process. The wire deformation was found to be proportional to the filling velocity. The apparent mean viscosity of melted resin can be inferred from the measured quantity of the deformation based on CD-Re correlation. The Lamb's formula also has been proved till Re=10 -6 fields through authors' study.
The vortical structure of the near wake of an axisymmetric bluff body in the region of low Reynolds number is experimentally investigated. Morel model which is the fundamental shape of a flying body is used as the bluff body. This model has interchangeable after-bodies with slanted bases having slant angles from 0° to 60°.The model is installed in a uniform flow in the test section of the water channel. And the velocity distribution in the near wake is measured by using laser doppler velocimeter. Also the structures of shedding vortices are examined by the flow visualization technique. Behind the model, it was contirmed that there were regular shedding vortices. As the slant angle of the after-body becomes larger, the frequency of the shedding vortices becomes shorter. The remarkable change of the vortex pattern owing to the variation in the slant angle of the after-body could not be confirmed. It was found out that the geometrical form of the vortex was an arch-type with a revolution.
To visualize the projectile acceleration process in a gas gun, a new method using the inline hologram of a slender wire is proposed and demonstrated. The hologram pattern is recorded by a streak camera via a mirror, which is moving between the wire and the recording plane. Since the miror is glued onto the nose of an accelerating projectile, Fringe spacings of the hologram pattern gradually become narrower with time due to the projectile motion. The acceleration process can he obtained precisely by analyzing the fringe spacings. It was found that (1) the acceleration time of the projectile in the launch tube of 1 m is about 14.1 ms, (2) the acceleration is almost constant except in the early stage, and (3) two kinds of oscillatory behavior of the projectile during the acceleration are recorded in the first half stage of the acceleration.
Visualization of flame front shape of high pressure turbulent premixed flame by using laser tomograpy was made for the purpose of exploring the influence of the turbulence intensity and ambient pressure on the turbulent flame structure. The high pressure combustion chamber was used, where the continuous combustion was possible. In order to quantify the complexity of the flame front shape, the fractal analysis was made. As a result, the fractal dimension increased with increasing the turbulence intensity and ambient pressure, and it was saturated to about 2.15.
Radiation heat transfer analyses between arbitrary bodies composed of numerous polygons and participating media composed of numerous polyhedrons are carried out.The numerical results are expressed by various computer graphics. And these methods are compared each other. Color representations are suitable for 3-D visualization of the numerical results, however, these expressions reduce the information when these graphics are transformed to monochromatic pictures. A graphical tool is essential for transforming the color graphics to the monochrome in order to proper verification of the numerical results.
Heated module make natural convection flow These phenomena have been studied with heated resistance elements on vertical board in silicone oil. We suspended powder of microencapulated thormo-chromatic liquid crystals in silicone oil. Liquid crystals suspension method shows visually infomation of temperature distribution. As a result of experiment, we could observe there as colored map, and consider relation between heat transfer and colored map.
Natural convection heat transfer around heated two cylinders with thermal stratification was investigated experimentally and analyzed nu-merically under the condition of setting them in a rectangle enclosure. The natural convection phenomena were measured quantitatively by thermo-couples and visualized by the liquid-crystal suspension method. As for an unstability of thermal plume from the cylinders, it found that the analysis results were good agreement with the experimental results.
It is very important to determine the acoustic properties of biological tissues for two major aspects; one is that the acoustic parameters give the physical properties that could not be detected by optical microscopy, and the other is that the data provides information for understanding echographic imaging.In the present study, a scanning acoustic microscope (SAM) system was equipped to measure the acoustic properties of biological tissue at the microscopic level.
Plant pathogenic Phycomycetes produce zoospores which can move in soil water toward the host plants. The zoospores of Aphanomyces cochlioides a causal fungus of the spinach root rot, are attracted to chemotropic stimulants in the host roots and root exudates. Cochliophlin A, 5-hydroxy-6, 7-methylenedioxyflavone was identified as one of host specific attractants from the root exudates. The zoospores are attracted topically at some parts of the root surfaces. To visualize the behavior of zoospores, we took microphotographs and recorded on video tapes. The zoospores attracted to drops of fluorocarbon FC-72 solution of cochliophlin A in water aggregated topically on the surface as well as that of host roots. The result of visualization suggested that the topical aggregation on the surfaces of spinach root or the FC-72 solution of cochliophilin A was guided by cochliophilin A and an additional factor like an aggregation pheromone.
The flow visualization and the image processing of boiling two-phase pipe flow of magnetic fluid under nonuniform magnetic field are conducted with the ultrasonic wave echo technique. From this visualization measurement, it is clarified that the distributions of void fraction and the bubble generation are strongly influenced by the magnetic field. Next, the stabilization of the two-phase flow is experimentally examined using the image processing technique, and the experimental results are qualitatively agreement with theoretical results. These fundamental studies on the flow visualization measurement indicate that the precise control and stabilization of the two-phase flow are possible by using the magnetic force of the fluid effectively.
The constructions and the fundamental studies of a high-intensity flash x-ray generator having two flash x-ray tubes are described. This generator consisted of the following essential components: a high-voltage power supply, a high-voltage pulser, a thyratron pulser, a turbo molecular pump, and two flash x-ray tubes. The high-voltage pulser employed a polarity-inversion-type transmission line with two high-voltage outputs. The combined ceramic condenser of about 5 nF was charged from -60 to -80 kV by a power supply, and the electric charges in the condenser were discharged to two x-ray tubes through 5.0 m coaxial cables after closing a gap switch by the thyratron pulser. Using a tube, the pulse widths were less than 200 ns, and the x-ray intensity was less than 5 μ C/kg at 0.5 m per pulse. The maximum (peak) values of the tube voltage and the current were about.110 kV and 3 kA, respectively. When two tubes were employed, comparatively stable two x-ray outputs were obtained simultaneously.