A discrete vortex method has been used for a variety of incompressible high Reynolds number flows as a treatable numerical simulation method. In this study, I suggest a simple method introducing discrete heat element without spoiling the basic algorithm of the discrete vortex method. As an example, heat transfer on the surface of an uncomplicated object such as an airfoil is applied. Detailed Content is on the basic explanation for the algorithm of this method.

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In this paper, numerical simulations of internal and external flows of circular tubes with consideration of heat transfer are performed on a PC-Cluster. To estimate thermal interaction between fluid and solid, both flows of thermal fluid and heat transfer in the tube walls must be considered. To analyze both regions of thermal fluid and solid simultaneously, the velocity in the governing equations is set to zero in the solid region. Almost all processes of the computation are parallelized based on the domain decomposition method, where the message passing interface (MPI) is used as a message-passing library. The flows and heat transfer of two circular tubes in tandem arrangement at a Reynolds number of 120 are analyzed.

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A numerical study has been made on chaotic behaviors of forced convection in the transition regime. The microscopic turbulent flow in porous media is governed with the short-distance turbulent mixing due to the interstitial vortex in pore and the long-distance one around the solid. Judging from the examination on Lyapunov exponents, it is considered that the chaotic behaviors have a close relevance to the transition to turbulent flow. The relation between transport phenomena in porous media and chaotic behaviors of flow has been discussed.

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In the present paper, state-of-the-art sensing techniques for transport phenomena in micro and nanoscale processes in connection with thermal engineering are overviewed. Especially, new optical techniques to measure wide variety of thermophysical properties of liquids and solids in microscale are presented. For mass diffusion coefficient, Soret forced Rayleigh scattering has unique characteristics of extremely short measuring time of about 10ms and small sample volume of about 1(mm)^3. For thermal diffusivity of thin films, dynamic grating radiometry has capability of sensing local anisotropy of high-conductivity material in situ. All of these new optical techniques have high spatial and temporal resolutions which have never been attained by conventional measurement tools.

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In the case of semiconductor silicon single crystal growth process by the Czochralski method, it is considered that degradation of the crystal homogeneity may be caused by the Marangoni convection. In coating manufacturing processes using polymer solution, 2-dimensional distribution of surface tension may arise due to temperature and concentration distributions of the organic solvent. In the present study, the surface tension scanning apparatus has been improved, which employs surface laser-light scattering technique (SLLS). In order to confirm the applicability of newly improved apparatus, some preliminary measurements were performed; (1) fixed point measurements of ethanol with open and closed air, (2) fixed point measurement as a function of time and (3) 2-dimensional distribution measurement. Results of the measurements indicate that the present apparatus has a potential to observe 2-dimensional distribution of surface tension "in situ".

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Two acoustic surface waves (with frequencies around 1MHz) with slightly different frequencies that are propagating in opposite directions and interfering on a solid wall are used for controlling liquid film flow on the solid wall. The liquid film flow are visualized by doped paint pigment and monitored by a digital video camera. When the frequency difference are small, a flow is induced by the interfering acoustic waves. The flow velocity first increases with increasing frequency difference when the frequency difference is less than 1Hz, and then, the velocity decreases as the frequency difference are larger than 1Hz.

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A novel optical measurement technique has been developed to investigate diffusion and transport phenomena at the chemical reaction interface in Lab-on-a-chip and micro-TAS. A micro-PIV technique was applied to measure velocity fields near the interface comprising pure water and oleic acid. Velocity and temperature at the interface were measured by using a caged-fluorescent dye. Velocity was obtained from the displacement of a peak value of the fluorescent intensity, while temperature was calculated by diffusivity of the dye. Results obtained from the present work will contribute to development of the next generation of microfluidic devices.

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A novel radiation temperature measurement method was invented. In the traditional radiation thermometry, an emissivity data of a sample is necessary for converting the detected radiation intensity into temperature with a particular calibration curve. On the other hand, temperature of the sample can be decided by finding the sensor temperature at which the radiation intensity is null in our method. Introduction of the null method into radiation thermometry eliminates the need for the emissivity value. The principle of the method was verified with a measurement system where a heater-equipped commercial thermopile device was driven with a thermal feedback circuit. Quantitative temperature measurement was achieved for the flat brass surface with black paint or with plastic tape. Furthermore, a integrated radiation sensor having a cantilever type thermopile, electric heater and thermocouple was made by the silicon micro-fabrication technology. Measurement test with the sensor showed that the method absorbs the difference in emissivity, and that local temperature distribution in the sensor influences the detection of radiation intensity.

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Quantitative measurements of electrokinetically driven flow and pressure driven flow were performed by micro-resolution particle image velocimetry (micro-PIV) in a cross-junction microchannel and a right-angle microchannel, for further development of Lab-on-a-chip and μ-TAS. The objective of the present study was to control electrokinetivcally driven flow which is frequently utilized to transport and separate a very small amount of fluid in microchannels. Velocity profiles of electrokinetically driven flow were affected by the configuration of micorchannel and can be controlled by the applied electric field.

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Turbulent heat transfer mechanism in the thermal boundary layers developing a drag-reducing surfactant solution flow has been experimentally studied. A 2-component LDV and a fine-wire thermocouple probe were used to simultaneously measure the velocity and temperature fluctuations. A cationic surfactant solution, water/CTAC/NaSal system with 30ppm weight concentration of CTAC, was used as the working fluid for drag-reducing flow. From the simultaneous measurements of u, v and θ, the turbulence transport terms such as the Reynolds shear stress and turbulent heat fluxes in the streamwise and wall-normal directions, as well as the characteristics of the velocity and temperature field, were investigated.

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For making clear the phenomena on the unsteady heat transfer with liquid film in two phase flow, the measurements are needed about unsteady film thickness and velocity profiles in the liquid film adding time-averaged values. It would be very important especially to estimate the dry out mechanism of liquid film experimentally on fuel rod around the spacer in the new fuel assembly of BWR. In this study, the unsteady velocity profiles would be estimated by the surface velocity profiles, which were detected experimentally by the tracking of the visualizing particles with image processing. As the particles were impacted and moving on the surface with transferring the properties with diffusions, the time-special tracking with various methods indicate the position of impacts and flows on the surface, which give the useful information about liquid film.

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The phenomena of heat transfer enhancement by turbulent coherent structures are indispensable to make high performance in heat transfer with a small pressure loss. Not only time-mean thermo- and fluid-dynamics but also unsteady and sequential thermo-fluid phenomena are very important to study and control the phenomena. The most percentage of heat transfer enhancement were given birth for very short time period, when the turbulent structures just came and make effect on the heat transfer field. But the time-dependent correlations between unsteady fluid-heat transfer fields are still unknown. In this study, the three-dimensional velocity measurement system by color image processing would be improved with unsteady multi-color fields and various detecting optical devices with features, and the unsteady enhancement processes would be investigated when the periodic vortex from cylinder were got collapse on a plane.

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The small diameter and relative flexibility of optical fiberscopes provide potential flow measurement solutions for difficult to access closed vessels and enclosures. The use of a pair of optical fiberscopes in conjunction with a stereo particle image velocimetry (PIV/PTV) system, in an un-optimized configuration, may lead to lead to gradual erosion of the transmitted image. In the present study, we analyzed the interpolation error at subpixel distances because of the spatial resolution imposed by the diameter of each fiber. Our analysis confirmed that PTV-SS method (Tani et al 2001) can be applied to a fiberscopic stereo PIV system.

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High-resolution time series particle image velocimetry (PIV) has been developed for measurements of turbulent flows. Velocity measurements up to 300Hz with 3969 vectors are successfully conducted in a turbulent mixing layer. New algorithm for the reduction of spurious vectors is also proposed based on the characteristics of the time series PIV. The developed time series PIV measurement is applicable to turbulent flows which show -5/3 law in the inertial subrange.

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Simultaneous measurement of OH and CH radicals by planar laser induced fluorescence (PLIF) is conducted for laminar premixed flames and lean premixed cellular flames. Effectiveness of CH PLIF as an indicator of the heat release rate is shown by comparing the results of CH PLIF experiments with numerical simulations. In laminar flames, the change of CH mole fraction with the equivalence ratio can be represented by CH PLIF. In addition, even in lean cellular flames, in which CH mole fraction is significantly low, CH fluorescence can be measured. These results imply that CH PLIF is applicable to estimate spatial variation of the heat release rate in the turbulent premixed flames.

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This present experiment developed a method for simultaneously measuring vapor concentration, droplet size and velocity in a spray by simultaneous application of LIF and ILIDS. To combine these two measurement techniques, we employed a Nd : YAG laser with a special optical arrangement in order to emit the laser beam at two wavelengths : one at 266nm to excite the fluorescence marker of acetone for LIF and a second at 532nm to illuminate the droplets for ILIDS. As the wavelengths of fluorescence differ from the scattered light at 532nm, the use of optical filters enables one to distinguish fluorescence from scattered ligh. The experimental results showed the diffusion of a vapor concentration and the difference of droplet motions classified by the droplet diameter.

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This paper describes an experimental application of planar droplet sizing technique, applied to the study of spray impingement onto a hot plate. By employing interferometric laser imaging for droplet sizing (ILIDS), including analysis of the out-of-focus droplet images, we can measure the instantaneous spatial distribution of droplet size. The experimental results showed that both arithmetic and Sauter mean diameters near the hot plate increased in contrast to the regions far from the plate. The measured droplet behavior in the vicinity of the hot plate demonstrated the important differences in the velocity and direction before and after impinging. i.e. the droplets moved upstream due to impingement reversal at the hot plate.

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Recent advances in micro actuators for thermofluid control are reviewed throughout the IEEE international conferences on micro electro mechanical systems from 1998 to 2002. The important contributions are discussed in terms of -basic phenomena, -micropumps or microvalves, -micromixers, -micro thermofluid machines or power MEMS, -integrated systems, and -boundary-layer control using micro perturbations. The author stresses that, in this field, remarkable progresses have been made and there are plenty of challenging works which lead to new possibilities for the thermofluid dynamics.

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The control of fluid flow in the micro channel is becoming an important technique in the development of the micro device for the vaio technology. This research focuses on the on-chip controller of a flow in a micro channel, and on the development of a control element. In this presentation, the characteristic of three kinds of sensors that have possibility of an on-chip fabrication are reported. The fabricated micro channel consists of the micro venturi, the mass flow meter, and the hot wire. The characteristic was investigated in the various conditions of the flow velocity and the several conditions of the channels.

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Behavior of DNA molecules in a ratcheting electrophoresis microchip (REM), a novel microdevice that can separate biomolecules such as DNA and proteins in aqueous solution using low applied voltages as low as 1V, was examined by a Lanvegin simulation. The device has been modified to start the electrophoresis in the direction normal to the electrode surface, which enabled us to give large area to the electrode without deteriorating resolution of separation. A Langevin simulation has been performed for DNA ions as well as H^+ and OH^- ions in pure water, in which an electric field is generated due to the voltage of the electrodes. Influence of electric charges of H^+ and OH^- ions on the electric field is also considered so that the Debye screening is well reproduced. The simulation clarified that the modified REM has much better capability to separate sample molecules with better resolution. Also it is tough against the Debye screening.

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Magnetic fluids are suspensions of ultra fine (5 to 15nm) particles coated with a molecular layer of dispersant in a liquid carrier such as water or kerosene. In this paper micro visualization of thermal behavior of ferromagnetic particles in magnetic fluids was investigated using an optical microscope system and Particle Image Velocimetry (PTV) data processing system. Real-time visualization of the Brownian motion and the chain-like cluster formation of two types of particles were carried out under non magnetic field and a magnetic field. The influence of the temperature variation on Brownian motion of ferromagnetic particles was investigated.

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We carried out microscopic analysis of ferromagnetic and paramagnetic colloidal systems by Brownian dynamics method. We analyzed secondary structures formed by chain clusters which are composed of paramagnetic particles in a dc magnetic field. Depending on the system height, wall and fat column structures were observed. We also analyzed the rotational dynamics of magnetic particles in alternating and rotating magnetic fields and discussed the relation between the rotational motions and apparent rheological properties.

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This paper deals with the flame shape and fluctuation in the lean burn of methane-air mixtures. Cellular or planar flames formed on a flat burner are observed, and the gas temperature is measured with a Pt/Pt-13%Rh thermocouple to find out the flame shape. When the equivalence ratio is higher than 0.74,planar flames are formed; cellular flames appear at lower equivalence ratios. As the equivalence ratio becomes lower, the cell size and cell depth are increased. The diffusive-thermal effect plays an important role in the appearance and characteristics of cellular flames. We also measure the fluctuation of brightness of premixed flames and obtain the power spectrum density of the brightness fluctuation. At low frequency range (f<0.035Hz), the power spectrum density is almost constant, i. e., the white noise is observed. At high frequency range, on the other hand, the 1/f^<3.5> spectrum is observed. In addition, the power spectrum density has a peak at high frequency range, under the condition that cellular flames appear.

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The present study is to clarify the relationship between the turbulent burning velocity and the turbulent flame configuration of hydrogen/oxygen/dilution gas mixtures, where the dilution gas is changed to N_2,Ar, CO_2,He keeping the laminar burning velocity nearly the same value. A laser tomography technique is used to obtain the flame shape. In the weak turbulence, the surface area of turbulent flame is found to be dependent slightly on the kind of dilution gas. The local burning velocity characteristics are discussed based on the local flame front configuration obtained by the flame tomograms.

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A novel technique is proposed for measuring an instantaneous spatial reaction zone profile of turbulent premixed flames. The technique is realized by combining multi-lens-camera photography with computer tomography. The technique is applied to measure a spatial profile of PET resin powder particles in a jet to verify its accuracy and validity. The results show that the 3D spatial mapping of the particles reconstructed with multi-dimensional data agrees well with the original picture, resulting in enough accuracy of the proposed optical diagnostics. In this report, error factors, for example aberrations of lens, positions of pictures and numbers of pictures used for CT reconstruction, are experimentally examined.

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The stabilization mechanisms of the inverted flames established in a rotating flow were investigated in order to develop a compact combustor with a high intensity and low NOx emission. The flame is sufficiently stabilized even at the equivalence ratio φ below φ=0.64 below which there is almost no production of thermal NOx because of the low temperature of the flame. The flame is also stabilized even in a high flow velocity of the mixture in the equivalence ratio φ=0.6. Therefore, the combustion of ultra low emission of NOx and high intensity can be realized by using the inverted flames established in the rotation flow.

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It is commonly known that NOx emissions of diesel spray flame increases when the fuel injection pressure is increased. On the contrary, higher fuel injection speed in a steady diffusion flame results in decreased NOx emissions. The authors have been investigated on this contradiction, and found that significant amount of NO is formed mainly in the region vicinity of the spray tip, causing the difference in NOx emission characteristics between steady and unsteady jet flames. The paper presents a brief results of experiment and simulation, and discusses concepts of NOx reduction in diesel engine based on the result.

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A numerical analysis on the combustion characteristics with preheated low-oxygen air was made for counterflow diffusion flame by using the detailed chemistry. The effects of preheating air and lowering oxygen concentration on the combustion characteristics and NO emission index were examined under the same maximum flame temperature. As the oxygen concentration decreases, the concentrations of HCN, N and NO increase, and the NO mass production rate increases and the fuel mass consumption rate decreases, thus NO emission index increases.

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More than 400,000 tons of wastes cooking oil a year are estimated to throw out. Part of them is thrown out to sewage line and then causes water pollution of rivers, lakes and oceans. Using the recycled cooking oil as fuel of engines would be a simultaneous solution of two big problems of the water pollution and energy saving including the reduction of CO_2. In this study, combustion observations of waste cooking oil were made to design a suitable combustion system of a heat-insulated engine fueled with the oil using a rapid compression and expansion machine.

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Recently, with the purpose of energy saving and environmental conservation, community services including general household to collect waste cooking oil have been actively pursued. In future, using the raw waste cooking oil as fuel of small sized engines will greatly contribute toward building the recycling-oriented society. However, operation of conventional small sized engines using the raw waste cooking oil is very difficult because of building up deposit on the combustion chamber wall. In this study, the raw waste cooking oil as fuel was applied to a heat insulated engine to eliminate the problems in the conventional engines. This paper describes performance of the heat insulated engine fueled with the raw waste cooking oil as fuel and demonstrate that the operation with the raw cooking oil as fuel is possible in the engine.

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Recently a great deal of waste PET bottles has been accumulated in the stock yards without any management. On the other hand in the ceramic kiln furnace commercial grade LPG is generally employed as a gaseous fuel and used simply as a heat source. It is very useful and important to replace a part of gaseous propane with an alternative fuel such as PET-resin powder from the view point of energy saving and low environmental impact. In this paper by varying the replacement rate of PET-powder under a constant combustion loading, combustion characteristics of the proposed ceramic burner are experimentally examined and analyzed by optical observation and measurements of temperature and composition.

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Increasing attention has been focused on a new alternative fuel, DME (Dimethyl Ether), from the energy security and environmental aspects. Recently, direct synthesis process of DME from methane of coal mine and/or gasification gas of low-quality coal has been successfully developed in Japan. The physical properties of DME are, in principle, similar to LPG, except the ignition temperature, and thus DME has a merit of being able to use LPG handling technologies. In addition DME has rather high cetane number suited for clean Diesel fuel. This paper describes fundamental combustion test results conducted by using diffusion and premixed burners. Experimental results demonstrate high potential of DME as a boiler and gas-turbine fuel.

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Experiments were made of the flame propagation process of a spray compound mixture to clarify the effects of fuel spray fraction and initial presser etc. on the combustion characteristics. A kerosene spray-propane-air mixture was ignited at the center of the constant volume vessel, high speed video observation was made of the spherically propagating flame, and the flame propagation speed was measured. Compounding the kerosene spray in the propane air mixture at high pressure (1.1MPa) enhanced the flame propagation speed in the whole combustible range, especially the enhancement was large for the mixture with an equivalence ratio around 1.1.

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To reduce its size and improve exhaust emission property, it is effective for spray type combustor to increase burning velocity by promoting such as fuel evaporation, diffusion, mixture of fuel and air. Excessive swirl inhibit the mixture in centrifugal direction of fuel and air to deteriorate combustion condition. This paper reports the coexistence of high load combustion and emission reduction experimentally confirmed having shorter flame length, compared to swirl type combustor, by making many air injection holes along combustion cylinder axis which causes creating small turbulence.

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Woody biomass is a hopeful energy resource to reduce greenhouse gas emission. Little amount of woody biomass is utilized for energy production, although Japan has much forest, and has large emission of greenhouse gas. Because most forests in Japan are located in steep mountain ranges far from urban area. Therefore, we must reduce the labor and the costs for ingathering and transportation of the woody biomass energy to utilize it in Japan. The object of our study is to improve the calorific density of woody biomass pellets, and reduce the transportation cost per unit energy. We adopted the semi-carbonizing method to achieve it. This study examined the optimum semi-carbonizing condition for pelletizing.

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From a viewpoint of environmental preservation and resource protection, the recycling of wastes has been promoting. Expectations to new energy resource are growing by decrease of fossil fuel. Biomass is one of new energies with prevent global warming. This study is an attempt to burn pelletized woody biomass (Bio-pellet) made from sawdust and logging residue in order to thermally recycle waste products of forestry and lumbering industry. Fundamental data on Bio-pellet combustion were obtained in an electric furnace. Combustion appearance, weight and temperature of pellets were investigated under specified furnace temperatures to obtain combustion characteristics such as ignition delay, burning period, char-combustion time and the change of weight decrease and temperature rise.

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We suggest possibility of two independence city from comparison of large quantities energy consumption in a big city from the situation of a local city about effective practical use of quality of woody bioenergy by this study. In particular it is necessary to do the recycle energy system that may make use of the thing that is different in the area where a consuming place and quality of woody biomass of electric energy in the local country concentrate on in one of the problem that quality of woody bioenergy surrounds as a good point.

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The bio-fuel, which is produced from the solar energy, is expected from the long-term viewpoint, because there is no fear of the carbon dioxide increase in addition to not drying up. The performance of the diesel engine operated by rapeseed oil, which has the potential of practical application as a bio-fuel, is examined. Though the rapeseed oil is produced as a food at present, there should be a different manufacturing method, when it is used as engine fuel. Generally there are 7 stages on the manufacturing process of rapeseed oil as a food. In this paper, the performance of the diesel engine operated by the oil of the manufacturing process of 7 stages is clarified. In conclusion, it is shown that the processing of 7 stages is useless, if it is utilized as a diesel engine fuel.

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One of the sources of unburned hydrocarbon discharged from the spark ignition engine is the fuel-air mixture confined in the piston ring crevice. In this paper, the process which the fuel-air mixture confined in the piston ring crevice blows out into the cylinder is treated. Calculation model composed of three elements is developed in order to clarify the phenomenon. Three elements are thermodynamic calculation in the crevice, non-steady flow jet in the cylinder and oxidation phenomenon of the fuel-air mixture in the jet. The detailed process which fuel-air mixture in the crevice oxidizes in the cylinder is quantitatively shown by the calculation results.

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High concentration of nitrogen oxide is detected in the exhaust gas during the cranking process of internal combustion engines. In this paper, the mathematical model which estimates the generation of nitrogen oxide in the cranking process is developed. The highest NO concentration in the first cycle is found by the calculated results. This fact can be explained by no residual gas and lowest rotational speed in the first cycle. The effect of the rotational speed on NO concentration is measured and confirmed by the calculated results.

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In the generic technology of the intelligent distributed energy system, there are micro gas-turbine and phosphoric-acid fuel cell in which the development has advanced recently. What becomes a case in which these machines are introduced as a cogeneration system with the problem is the load leveling of heat and electric power. Then, this study was noticed in absorption cycle using the thermo-chemical reaction for absorption heat pump and refrigerating machine. The purpose of this study is to clarify the thermal engineering characteristics of the system in which storage and conversion (temperature upgrading and transformation) and the power storage and conversion (mechanical energy) of thermal energy using absorption cycle are possible.

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Electric power has been generated by using reciprocating-flow super-adiabatic combustion in a thermoelectric porous element which is made of many slim π-shaped FeSi_2 semiconductors inserted into the two adjacent pores of the ceramic honycomb core. A low calorific gas of equivalence ratio of about 0.1 could be burned by the super-adiabatic combustion in a porous catalyst. A trapezoidal temperature profile is established in the flow direction and a steep temperature gradient is yielded in the thermoelectric porous element. As a result, electric power could be obtained with the thermal efficiency of 0.04%.

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The research project of "Technology for MGC (Melt-Growth Composite) ultra high-efficiency gas-turbine system" has been started since 2001. MGC material is known to show high strength unchanged at the temperature as high as 1700℃. It is considered that NOx emissions must increase in the temperature condition, to which MGC will be applied. Therefore, research of a unique low NOx combustor, with which the increase of NOx formation can be suppressed drastically, has been carried out. The key techniques are a rapid mixing & combustion technique, a staged combustion technique, and a technique to apply MGC to combustor liners. This paper describes the outline of the research activities.

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Effects of radiative energy absorption via decomposed gaseous products on spontaneous gas-phase ignition over a combustible solid heated by external radiation are studied numerically. Numerical model includes time-dependent heat and mass transport and chemical reactions of gas- (exothermic) and solid-phase (endothermic) in three-dimensional domain. PMMA is considered as solid combustibles since rich physical/chemical data is available. Ignition characteristics are examined in different absorption coefficients of MMA vapor and in various orientations of the solid combustibles. It is shown that the ignition delay time gives complex responses in various orientations of the sample (sometimes delays, but sometimes enhances the ignition), while is rarely affected qualitatively by the absorption coefficients, 0.1&acd;0.2 (atm)^<-1>(cm)^<-1>, considered in the present study. Since the dynamic motion of the 'energy-absorbed-HOT-gases' plays an important role in the prior process of the ignition, precise 3-D transport processes must be considered for an understanding of the absorption effects.

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Some metal compounds in coal vaporize and form fumes during the combustion. The fumes are usually contained in the exhaust gas. For coal-fired combined power generation systems such as pressurized fluidized bed combustion, hot metallic vapors are introduced in gas turbine. As this phenomenon causes corrosion problem of the turbine blades, it is necessary to control the formation of those fumes, which include alkali metal compounds. In this paper, the evolution behavior of alkali metal compounds, especially for sodium compounds, has been studied, using a drop tube furnace with a low-pressure impactor.

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Natural convective flows around upward-facing, horizontal heated plate attached with a vertical heated plate at the edge were investigated experimentally. The test fluid is water. The widths of horizontal heated plates, W, and the heights of vertical plates, H, were changed as W=100&acd;350mm and H=0&acd;150mm. Visualization of flow and surface temperatures has been carried out with dye and liquid crystal thermometry. Local heat-transfer-coefficients were also measured. The result shows that the incoming flow from the vertical plate side disappears when the height of the plate exceeds H/W=0.1. It is also found that the local heat-transfer-coefficients of the horizontal plate are increased with the height of vertical plates.

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A numerical analysis was made on a downward-facing plate for air, saturated vapor and saturated liquid. Basic equations for mass, momentum and energy are discretized by finite difference method and numerically solved by the HSMAC method. The computation domain is divided into many sub-spaces and arranged to investigate the edge effect of the plate. Velocity profiles obtained by numerical simulations agree well with those of experiments. The velocity and temperature fields are affected by Prandtl and Rayleigh number. Nusselt numbers are compared with experimetal datas.

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The structural characteristics of turbulent natural-convection boundary layer in air along a vertical heated plate have been experimentally investigated. Through the velocity measurement with a particle image velocimetry, the relation between turbulent statistics and large-scale fluid motions in the outer layer of the boundary layer is discussed in detail, especially paying attention to the behavior of Reynolds shear stress, and it is found that the large-scale eddies, which control the structure of the outer layer, contribute largely to the production of turbulent energy. In addition, the change in the maximum velocity location due to flow windings observed in the whole visualized region may lead to the peculiar profile of the Reynolds shear stress.

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