In this paper, a new method of line element fitting by means of Hough transformations is proposed in order to separate and recognize particle pathlines overlapping each other, on a digitalized flow visualization photograph. An image of particle pathlines is produced by a tracer method. Hough transformations are applied only to the edges of particle pathlines. The edges are obtained by tracing pixels that have high gradient value in the image. Results obtained by the method with Hough transformations are presented for the flow visualized images such that two particle pathlines are overlapping each other.

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Schlieren photography is one of the most popular flow visualization techniques. Although its photographic data include density information, however, it have been used only for qualitative analysis.
The objective of this research is to develop a measurement technique for quantitative analysis using Schlieren photography. With this it will be possible to measure instantaneously the whole space of the density field.
This paper describes the theoretical background, the execution problems, and the necessary correction techniques. The experiment was made for a two dimensional CO ₂ jet injected into air. The results show that air entrainment can be quantitatively analyzed with sufficient accuracy, when appropriate correction is employed.

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A new method to measure a velocity distribution through the analysis of the visualized image of a flow is developed. The method ischaracterized by two points. One is the very high speed performance. The other is its very simple and economical analyzing system. Using the system, it takes only 45 see. to analyze a couple of 256*256*8 bit images and to obtain a set of velocity vectors. And it should be noted that it enables to evaluate the reliability of the measurements quantitatively by using correlation coefficients.

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A real-time velocity measurment system based on the digital image processing approach has been applyed to the lid-driven cavity flow. This system consists on TV camera, a digital imege processor interfaced with a micro-computer, and high-speed imege analyis algorithm. Flow field is visualized by a lot of tracer particles, and the velocity vectors are extracted full- automatically from the particle images in consecutive frames.

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CAFV(Computer Aided Flow Visualization) system for the gas dynamics has been developed. The flow field is visualized using LIF of I ₂ seeded in Ar and monitered by high sensitive vidicon camera. Image data from vidicon camera at many different visualized planes are stored up in personal computer in order to estimate three-dimensional information on the entire flow field. For the purpose of removing the noise, one frame data is accumulated many times and averaged. This system is applied to two flow fields, i.e., the free jet expanding into a vacuum chamber and the interacting flow field between a skimmer and the free jet. The contour lines of fluorescence intensity on each flow field are depicted effectively.

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The three dimensional bed configuration and its variation at flood time were observed from the bridge built over the lower reaches of Teshio river by using supersonic sounder.

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The present experiment was undertaken to evaluate the association and the effect of mouth breathing in the initiation and the progression of periodontal disease. Artificial mouth model-fulfilling nearly all the criteria of natural mouth was made and a visualization survey of flow patterns was carried out using Dye (Uranin).
As the result of this experiment, the following characteristics were observed in the flow patterns.(a)In case of deep overbite, the inhalation flow was concentrated on the palatal gum margin and then ran into the throat alongside hard palate. And on both sides of the upper arch, it was stagnant with some feeble circulations. (b)In normal occulusion, it was the same as (a) pattern, but concentrated flow was delayed in comparison to (a) pattern. (a)In mandibular prognathic relation, the flow pattern was initially concentrated, then immediately changed into unsteady and turbulent.
The region of concentrated flow in the artificial mouthmodel was coincident to the area of tension ridge (upper anterior), suggesting that mouth breathing may be one of the important etiologic factor of periodontal disease.

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Three-demensional laminer-flow in curved square channel has been investigated by using flow visualization technics. The hydrogen bubble method was applied to trace the flow. The flow velocity vecter was measured at five streamwise stations along the main flow direction. The flow intensity is of 1000 in Reynolds number and the channel is made of a 90° bend with curvature ratio of 2 having an inlet and outlet straight channel.
The result of measurement was compared with that of numerical analysis.

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The steady vortex induced by the flow supplied from tangential direction withdrawn through a hole at the center of the bottom of a vessel is considered. And the flow due to the eccentric sink is added to these vortex flow is also considered.
The purpose of this paper is to elucidate the fundamental feat-ures of the flows of these two types. By using hydrogen bubbles method as visualization technique, the flow characteristics was visualized, and compared between the two types.

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When we analyze the compressible flow field including shock wave by computational calculation, the solution diverges because of the discontinuity of shock. If we use transformed-Fluid-in-Cell Method, the discontinuity is artificially smoothed and we can analyze the flow field stably. But in the analysis by transformed-Fluid-in-Cell Method, mesh form influences the solution. So we applied the Adaptive Mesh Method to transformed-Fluid-in-Cell Method and got the solution not influenced by mesh form in the analysis of super sonic flow field around blunt nosed body.

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The unsteady transonic flow induced behind a shock wave is of importance to study unsteady shock wave loading over bodies. the present paper reports experimental and computational investigation of unsteady transonic flow over an elliptical cylinder in a shock tube. The experiment was conducted in a 60 mm x 150 mm shock tube equipped with double exposure holographic interferometry. To simulate the unsteady transonic shock tube flow, Total Variation Diminishing (TVD) finite difference scheme is applied to the Navier - Stokes equations. The complicated unsteady transonic flow accompanied by shock waves was successfully simulated with a high resolution. The computational isopycnics are consistent with the interferogram.

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In this paper, first, the formation process of pseudo-shock wave in a straight square duct is shown using high speed schlieren films. Second, the relation between the locations and structures of pseudo-shuck waves is discussed using wall pressure distribution measurements and schlieren pictures. Third, the internal structure of λ-type pseudo-shock wave is investigated in detail by total pressure profile measurements.

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In order to obtain an exact shock transition angle from Mach reflection to regular reflection, an effectt of a boundary laser should he considered. For that purpose. we have conducted the experimental research on the shock wave reflection over the liquid surface, since the boundary condition at liquid surfaoe is different from that of the rigid surface. The shock wave reflection was visualized by using a double exposure holographic interferometryi and the shock transition angle was obtained from the interferograms. The present transition angle is closer to the I.henritical angle than the case of the rigid wall.

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The flows past circular cylinders installed in a dusty-gas shock tube were visualized by a high-speed schlieren method, a pulsed laser holographic interferometer method and a shdowgraph method. The behaviour of shock waves past circular cylinders in a dusty-gas, the development of dust free region and the formation of vortices behind the circular cylinders are discussed.

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Recently, underwater shock wave focusing has been applied to the non-invasive disintegration of kidny stones. However, due to the highly non-linearity, the shock wave focusing phenomenon is stil unresolved. Therefore, it is crucial to clarify this complicated phenomenon. In this paper, the experimental and computational study of the underwater shock wave focusing is presented. The underwater shock wave was generated by using a 5mg lead azide (Pb(N3)2) pellet and a 10mg silver azide (AgN3) pellet, and reflected by an ellipsoidal cavity, and focuses at 2nd focal point. The focusing process was visualized by using holographic interferometry. The peak pressure along the axis of the reflector were also measured by Kstler 601H pressure transducer. The interferometric results were compared with the numerical simulation conducted by using a Total Variation Diminishing (TVD) finite difference scheme. A good agreement was obtained between the computation and experiment.

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The present paper reports the visualization study of the initiation of a shock wave generated by a rebounding bubble and a micro-jet induced when the bubble is collapsed. The underwater spherical shock wave is obtained by using a 10 mg silver azide(AgN3) pellet, and visualized by using double exposure holographic interferometry. In order to understand the quantitative properties of this phenomenon, the density and pressure distributions were evaluated by measuring the interference fringes and using Tait equation. Consequently, the sudden pressure change when the shock wave is generated by the rebounding bubble and the structure of the micro-jet were clarified

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With the progress of cryogenic engineering, unsteady behavior of cavitation vapor bubble collapse in low temperature liquids has been within our scope of great interest. In this paper, phenomena of pure vapor bubble collapse and rebound in low temperature R-12 liquid compressed by the reflected shock wave are treated. The rebound of collapsed bubble in low temperature range is visualized by shadowgraph method using high speed frame camera (lmacon-790) and pulse light. Observed behavior of bubble in liquid R-12 is compared with numerical solution that calculated from Rayleigh-Plesset differential equation. As the results, rebound of vapor bubbles in low temperature liquid and strong spherical shock wave emission are visualized.

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For investigation of two phase flow characteristics, it is important to measure their void fraction, and bubble population and sizes. Although X-Ray, Gamma-Ray and electrical condutivity probe have been used to estimate these values, the former two methods may be so complicate and more expensive, the latter distubs flow condition.
In this paper, a simple measuring technique by using laser beam is treated with direct contact condensation processes of mixing streams at high velocity ratio, which is observed within such a condesing ejector and ECCS of reactor etc. It may be possible to visualize two dimensional pattern of bubble distribution along the flow direction by using this method, which is based on the detection of laser beam acrossa chanel. The relationship between the numbers of bubble and the intensity of laser beam and effectiveness of this technique are discussed.

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An experimental study has been performed to investigate the influence of density inversion of water on the transient free convection b ehavior in a cooled circular tube. The experiments were carried out under the condition that the tube-wall temperature was successfully decreased at a uniform rate. A holographic interferometry technique was adopted to measure the time-dependent distributions of the temperature in the tube. It was observed that the temperature-distribution characteristics were to a great extent changed by the cooling rate of the tube wall, along with the time-dependent sequential flow patterns. The heat-transfer characteristics along the inner tube wall were also extensively determined.

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This paper treats the experiment of flow visualization in the clean room by means of tabacco smoke and give the results.
Secondly, mesurement of air flow velocity was carried out in the same condition using 3-dimensional ultra sonic anemometer and we got the results of velocity distribution.
Close agreement observed by visualiztion and mesured results are obtained.

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We developed automatic data acquisition system in order to visualize velocity distribution in clean room using 3-dimensionai ultra sonic anemometer.
The probes of the anemometers can be set in any mesuring point by the robot with wireless operation. Acquired data are transfered from the anemometers to the computer by RS232C wireless MODEM and the averaged velocities of X, Y, Z components are calculated and outputed on CRT or to the plotter.

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Experiments were performed to evaluate the variation of air flow distribution in the room with air jet angle, air flow rate and inlet air temperature from the outlet of air conditioner for improving the human comfort.
In a present study, measurement for visualizing air flow and for evaluating the air flow distribution in the room were made of by using a particle tracing method. Air flow visualization was carried out by using TV camera and then air flow distribution was evaluated with image processing based on tracer particles image data recorded by TV camera. The good agreements between the air flow distribution data obtained using the hot wire anemometer and that evaluated from the present tracer particles image processing method were obtained within the present experiment range.

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In recent years, computer graphics have become important and useful to visualize in the area of numerical simulation results. Sometimes it can be expressed some beautiful and unexpected results. In this paper, several visualization examples such as an air current and temperature distribution in three dimensional analysis, numerical simulation of a tsunami, stress spread of a soil-structure interaction, are introduced by using VHS video.

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It is necessary to know the air-flow pattern through fins, in order to improve the performance of heat exchangers for air-conditioners. This report presents some visualized examples of high performance fins, that is, convex louvered fin and inclined louvered fin. Aluminum powder method and dye injection method are used where air is replaced with water. In that case Reynolas number for visualized models is adjusted so as to agree with that for real heat exchangers. The visualized results of air flow utilized for deciding the louver arrangement of high performance louvered fins.

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In order to conduct an effective computer simulation for the thermal design, flow visualization was performed. A transparent model, incorporated with boxes which could be supplied a specific heat flux, was used. The mist method by liquid paraffin was adopted for air flow visualization, and the thermo graphic method was used for temperature distribution measurments. By the comparison of analysis and experimental results, the simulation method and boundary condition were examined.

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In this study, the relative flow patterns of a centrifugal blower impeller were visualized by the spark tracing method. The stationary image of flow patterns in the rotating impeller was observed using the rotating image stopping processor.
In this way, the flow patterns near the inlet of impeller and blade tip were caught using line and needle type electordes. The difference of flow pattern in each flow rate was made clear.

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The flow visualization of two vertical-axis-wind turbines, Savonius and Cyclogyro rotors, has been performed by using a three-dimensional smoked tunnel, a system of still cameras and a set of strobo-lighting systems. It can be seen by observing the flow pattern for nonrotating turbines that the driving torque at the initial stage of rotation is generated by the lift of one blade and the drag of other blade in the Savonious rotor for almost every azimuth angle whereas the driving torque is very small in the Cyclogyro rotor. For rotating turbines, it can be observed that the sinusoidal change of lift and drag of the rotors generates a series of shed vortices like Karman vortex streets and the flow separation and reattachment on the rotor blades occur cyclically through the rotation in both types of rotors.

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The authors have been investigated the characteristics of a wave energy conversion system of pendulum type, located at the seashore, with a sea-wave channel in Muroran Institute of Technology, Muroran. The aim of the study is to search a new natural energy resource.
In this paper, the results of observations of wave streak-line patterns around a wave-receiver plate, which oscillates as a pendulum, are presented with several illustrations of photographs and figures.
In the case of proper load for the receiver plate, wave streakline patterns tend to form series of circles at offshore side of the receiver plate; in the case of light load, they tend to form series of ellipses with vertical long axes; and in the case of heavy load series of ellipses with horizontal long axes.

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This papper describes an experimental study of the flow characteristics of swirl type combustor, which is extremely important in the combustor of gas turbines, combustion furnace, etc.
In this stydy, the flow characteristics of swirl type combustor are measured using the kind of flow visuarization method(spark tracing method, tuft sttik method), and with the results, we have clarified the flow pattern for location of swirler.

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The airflow patterns in the cylindrical expansion-chamber mufflers inserted with an inletpipe or a tailpipe respectively were visualized by spark-tracing and smoke-wire methods. Next the spectra of sound pressure levels (SPLs) of the flow noise generated secondarily in the mufflers were measured.
It is obvious from these experimental results tnat the frequency cnaracter-istics of flow noise change with the flow pattern determined by the ratio of the distance between either open ends of an inserted pipe and a chamber to pipe dlameter. The SPLs for the tailpipe-inserted mufflers show moderately high values in the wide range of frequency as compared with those of the inletpipe-inserted mufflers, owing to the occurrence of the recirculation flow in the surroundings of the inner pipe.

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Flow visualization of natural convection of air and a magnetic fluid in a cubic cavity has been carried out by using a liquid crystal. Temperature distributions on the wall are observed and developments of natural convection are qualitatively investigated. When a magnetic field is applied, dynamic characteristics of natural convection of a magnetic fluid are different from those in a nonmagnetic field. These phenomena are dependent on a direction of gradient of a magnetic field and its strength. Numerical simulations are also performed. These results are compared with experimental results.

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Visualization of Natural Convection Heat Transfer from a Vertical Wavy Surface Composed of Isothermally Heated Convex/Concave Semicircular Cylinders.
by Koki Kishinami *, Hakaru Saito *, Ikuo Tokura t, Norihiro Bando ** Natural convective heat transfer from a vertical wavy surface having heated convex/concave semicircular cylinders has been studied experimen-tally, considering the effect of heat conduction in unheated elements.
Heat transfer characteristics are discussed based on visual observations of the velocity and temperature fields by using micro-particle trajectories and a Mach-Zehnder interferometer.
The parameter S (= B R / Gro1/4 ) was introduced through a vectorial di-mensional analysis and clarified that it indicates to play an important role in the interaction between the fields of fluid convection and the heat con-duction regions.

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In order to clarify flow around a circular cylinder set normal to a plane wake of an upstream circular cylinder of the same diameter, a windtunnel experiment and an open water-channel experiment have been performed at Reynolds-numbers ( based on the diameter of the cylinder and the main velocity ) of 2.9×104 and 680, respectively. Surface-flow patterns of the downstream cylinder and flow patterns around the two cylinders were visualized respectively by the oilfilm and the hydrogen bubble methods. The flow patterns were found to be strongly dependent on the ratio of the distance between two cylinders to the diameter; they can be classified approximately into 3 patterns depending on the ratio. Time-mean and fluctuating pressures on the surface of the downstream cylinder were also measured and presented in the form of isoplethes.

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This report explains about the aerodynamic forces acting on a smooth ball and a dimpled ball over a wide range of Reynolds number and spin rate.
The drag coefficient and lift coefficient were measured using wire strain gauges. Applying the spark tracing method, the separation points on balls were visualized clearly.
By this experiment, the drag and lift influenced by separation points, were made clear aerodynamically.

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Recently, in a steady free shear layer, it was found that three dimensional streamwise vortices contributed to the mixing across density interface. However, in an unsteady stratified flow, even the origin of these vortices has not been confirmed yet.
In this paper, the breaking process of the interface in an unsteady exchange flow has been investigated experimentally. Experimental results show that streamwise vortices but spanwise vortices do not play an important role in interfacial breaking of an exchange flow system.

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The flow around a ship model when operating in shallow waters was observed by use of woolen tuft and camera in a small towing tank. From present flow visualization tests, it was observed that the flow around the stern changed when the water became shallow.

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A sound is generated by a plane jet impinging on a circular cylinder in the same way as the edge tone. The aim of this paper is to elucidate the relations between the generated sound and the vortex structures in the jet and near the cylinder. The vortex structures were visualized by using a rake of smoke wires, being synchronized with the generated sound. In order to obtain flow directions around the cylinder, the flow field marked by smoke was exposed to two-colored strobe lights which were radiated at different time. Positions of the vortices were obtained with respect to the phases of the generated sound. The intensity of the sound was found to be related to the size and arrangements of the vortices.

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Vortex structures in a separation-reattachment flow (separation bubble) formed at the leading edge of a blunt plate with right-angled corners were studied by a hydrogen-bubble flow visualization technique. Two kinds of hydrogen-bubble probes were employed; one is a single platinum wire of 0.05 mm diameter attached to the surface of the plate to visualize the instantaneous flow near the surface, while the other was a seven-wire rake which was used to visualize secondary flow patterns in the separation bubble. Reynolds number based on the thickness of the plate and the approaching velocity was 1200. Main results can be summarized as follows. (i) The secondary flow patterns have a typical spanwise distance which increases downstream, its value on the reattaching line being about 0.35 times the length of the bubble; (ii) there exist longitudinal vortices whose axis is inclined with respect to the longitudinal direction in such a way that their upstream side is nearer to the surface than their downstream side is.

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