Yuichi Murai
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View article: Hydraulic Transport of Large Solid Particles in Inclined Pipes Under Pulsating Flow Conditions
Hydraulic Transport of Large Solid Particles in Inclined Pipes Under Pulsating Flow Conditions Open
The pressure loss due to the hydraulic transport of large solid particles should be predicted for the design of subsea mining systems. The mixture flow in a flexible jumper is expected to be unsteady during lifting operations in an actual …
View article: Digital detection of play characters’ relationships in Shakespeare’s plays: extended cross-correlation analysis of the character appearance frequencies
Digital detection of play characters’ relationships in Shakespeare’s plays: extended cross-correlation analysis of the character appearance frequencies Open
We propose a method for visualizing literary works that quantitatively extracts the mutual relationships among play characters from the narrative of a storyline. The method first determines the cross-correlation of the appearance frequenci…
View article: Function of the turbo‐sail airfoil applied to the Darrieus wind turbine
Function of the turbo‐sail airfoil applied to the Darrieus wind turbine Open
The use of a turbo‐sail airfoil to improve the power generation of a Darrieus wind turbine was examined. The turbo‐sail airfoil comprises a symmetric blade from which a high‐speed tangential jet is produced to suppress flow separation. For…
View article: Bubble clustering in turbulent boundary layer on a moving wall utilizing belt-driven system
Bubble clustering in turbulent boundary layer on a moving wall utilizing belt-driven system Open
For simulating the behavior of air bubbles injected into the turbulent boundary layer developed beneath the bottom of a ship, we propose a novel experimental system for a different driving force on flow from the bulk pressure gradient. In …
View article: Measurement of 3-D flow structure around densely arranged out-door units of air conditioner
Measurement of 3-D flow structure around densely arranged out-door units of air conditioner Open
Air flow field around narrowly arrayed out-door units of air conditioners is investigated experimentally under real-world operation conditions. The air flow velocities at the intake panels and exhaust ports of individual units are measured…
View article: Measurement of Multiphase Flow in an Air-lift Pipe using Ultrasound
Measurement of Multiphase Flow in an Air-lift Pipe using Ultrasound Open
Air-lift two-phase and particulate three-phase flow in a vertical pipe has been measured by ultrasound with the aim of revealing the transient dynamics of the air-lift performance. Changing the gas flow rate and mass loading of solid parti…
View article: Low-Cost 3D-PTV Utilizing Rainbow Light Illumination And Artificial Neural Network Applied To Rayleigh-Bénard Convection
Low-Cost 3D-PTV Utilizing Rainbow Light Illumination And Artificial Neural Network Applied To Rayleigh-Bénard Convection Open
Building on the novel methodology for three-dimensional (3D) color particle tracking velocimetry (PTV) proposedearlier by our research group, an improvement and an evaluation of the method is presented in this study. The method utilizes on…
View article: Lift coefficient of bubble sliding inside turbulent boundary layers in an inclinable channel flow
Lift coefficient of bubble sliding inside turbulent boundary layers in an inclinable channel flow Open
The behavior of bubbles traveling in the proximity of a tilted wall is studied experimentally to understand the fundamental sliding motion of bubbles inside turbulent boundary layers along an inclined wall. The qualitative visualization of…
View article: Overview of Ultrasonic Spinning Rheometry: Application to Complex Fluids
Overview of Ultrasonic Spinning Rheometry: Application to Complex Fluids Open
A novel rheometry termed ultrasonic spinning rheometry (USR) is overviewed in this paper. This methodology utilizes ultrasonic velocity profiling as a representative velocimetry for various complex fluids including multi-phase state. The U…
View article: Evaluation of time-dependent rheological property in the coagulation of skimmed milk by ultrasonic velocity profiler
Evaluation of time-dependent rheological property in the coagulation of skimmed milk by ultrasonic velocity profiler Open
We propose a method to evaluate time-dependent rheological properties, shear stress, effective viscosity and shear rate, of coagulating curd of the skimmed milk as an analog of cheese products. Ultrasonic spinning rheometry was adopted for…
View article: Frequency characteristics of void wave on gas-liquid two-phase flow in a horizontal channel with two-dimensional expansion
Frequency characteristics of void wave on gas-liquid two-phase flow in a horizontal channel with two-dimensional expansion Open
Void wave, which is a spatio-temporal fluctuation of the void fraction of air bubbles in turbulent flow of water, appears beneath the bottom of a ship with an air-lubrication system when the frictional drag is reduced. Controlling the void…
View article: Monitoring of Bubbly Flow by Ultrasonic Pulse Echography
Monitoring of Bubbly Flow by Ultrasonic Pulse Echography Open
本報では,超音波パルスエコグラフィーを用いた気泡流の計測技術をいくつか実用例を挙げながら説明する.この計測技術は気泡径によって計測原理が異なってくる.ミリサイズ以上の気泡の場合は,個々の気泡から反射されるエコーを区別でき,エコー波形の分析より個々の気泡の情報(気泡径や速度など)を取り出すことができる.また,これらの情報を積分することで,気相の体積流量を推定することも可能である.一方,サブミリサイズの微小気泡では,個々の気泡からのエコーが重なり気泡の区別ができないため,流路内…
View article: Development of eddy viscosity measurement system utilizing velocity profiler
Development of eddy viscosity measurement system utilizing velocity profiler Open
We propose a novel turbulent eddy viscosity profiler to evaluate the influence of interactions between turbulent eddies and dispersed materials as an effective eddy viscosity in Taylor-Couette geometry for frictional drag reduction studies…
View article: An experimental study on aeration and stirring process by rotating ventilated hydrofoils
An experimental study on aeration and stirring process by rotating ventilated hydrofoils Open
We have conducted laboratory experiments on air entrainment and bubble generation by rotating ventilated hydrofoils aimed at reducing power consumption by subsurface aerator. The negative pressure generated on the hydrofoil drives the atmo…
View article: Frictional drag reduction by bubble injection in turbulent boundary layers: Experiment with long model ship and full-scale estimation
Frictional drag reduction by bubble injection in turbulent boundary layers: Experiment with long model ship and full-scale estimation Open
Drag reduction by bubble injection in turbulent boundary layers was investigated using a 36-m-long flat-bottom model ship. The model ship was towed at 8.0 m/s, resulting in a downstream-distance-based Reynolds number as high as 2.9 × 108. …
View article: Ultrasonic velocity profiler applied to explore viscosity–pressure fields and their coupling in inelastic shear-thinning vortex streets
Ultrasonic velocity profiler applied to explore viscosity–pressure fields and their coupling in inelastic shear-thinning vortex streets Open
A method for simultaneous estimation of viscosity and pressure fields in inelastic shear-thinning fluids is developed by means of ultrasound velocity profiling technique (UVP). In the method, equation of continuity, rheological model and p…
View article: Nonintrusive In-Line Rheometry Using Ultrasonic Velocity Profiling
Nonintrusive In-Line Rheometry Using Ultrasonic Velocity Profiling Open
We present a new approach to realize nonintrusive in-line rheometry without measuring the pressure difference along the pipe, which is required in conventional methods that insert pressure probes in the pipe. The rheometry utilizes unstead…
View article: Step response of turbulent structure inside a horizontal bubbly channel flow due to sudden change in void fraction
Step response of turbulent structure inside a horizontal bubbly channel flow due to sudden change in void fraction Open
Performance of bubbly drag reduction (BDR) can be improved by repetitive bubble injection (RBI) which provides spatiotemporal fluctuation of local void fraction, termed void waves, to enhance momentum exchange between turbulence and bubble…
View article: Influence of perturbations with hairpin vortices on generation process of turbulent puff in pipe flow
Influence of perturbations with hairpin vortices on generation process of turbulent puff in pipe flow Open
Visualizations of transition process triggered by disturbance injection in pipe flows were conducted. In order to investigate the influence of hairpin vortices formed by interaction between the mainstream and the injected jet on the transi…
View article: Savonius wind turbine performance in high turbulence and its improvement by jet supply
Savonius wind turbine performance in high turbulence and its improvement by jet supply Open
Savonius wind turbines are utilized in urban area subject to high turbulence. Past studies for the turbine were conducted for the turbulence intensity lower than 10%. We conducted a series of wind tunnel experiments at high turbulent inten…