Faculty Profiles - UCHIYAMA, Tomomi

Papers - UCHIYAMA, Tomomi

Division display 261 - 280 of about 297 ／ All the affair displays >>

Numerical Simulation of Flow around an Oscillating Cylinder by Vortex in Cell Method

DEGAWA Tomohiro, GU Qiang, UCHIYAMA Tomomi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2018 ( 0 ) page： S0510105 2018

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

In the present study, we propose a method for calculating the fluid dynamic forces acting on bodies in a two-dimensional simulation of a flow around a moving body by using the vortex–in–cell method. The body is represented using the volume penalization method which introduces the influence of the body on the flow as an external force in the form of a penalization term into the Navier–Stokes equation. The pressure field is computed by solving the Poisson equation, which is derived by obtaining the divergence of the Navier-Stokes equation. The pressure and viscous stress on the body surface are obtained from a quadratic function along the vector normal to the surface. A flow around a circular cylinder oscillating in still water is simulated, and the fluid dynamic force acting on the cylinder is calculated using the proposed method. The velocity profiles across four cross-sections at three different time points agree well with the results of a measurement conducted using a laser Doppler velocimeter. The in-line force acting on the cylinder agrees with the results of the simulations performed using the boundary-conforming formulation.

DOI： 10.1299/jsmemecj.2018.s0510105

CiNii Research

Numerical simulation of jet issuing diagonally upward into density-stratified fluid in cylindrical tank Reviewed

Degawa, T, Uchiyama, T, Aozasa, I, Ishikawa, A, Motoyama, K

J. Power and Energy Eng. Vol. 6 ( 3 ) page： 38-52 2018

Control of air bubble cluster by a vortex ring launched into still water Reviewed

Uchiyama, T, Kusamichi, S

Int. J. Chemical Engineering and Applications Vol. 8 ( 1 ) page： 37-46 2017

Numerical Simulation of a Vortex Ring Impacting with a Density Interface of Density-stratified Fluids

ITO Takenori, DEGAWA Tomohiro, Uchiyama Tomomi, TSUNODA Hiroyuki

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2017 ( 0 ) page： S0520406 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

This study simulates the behavior of a vortex ring launched toward the interface of a two-layer density stratified fluid and the resulting mixing phenomena between the fluids. Initially, the density-stratified fluid is in a static condition in a tank. The upper and lower fluids are glycerol aqueous solution and an aqueous solution of potassium dihydrogen phosphate, respectively. The vortex ring with a diameter of 26.4 mm is launched vertically downward from the upper fluid region. It travels by the vertical motion toward the density interface. The Reynolds number, based on the circulation of the vortex ring, is 3500. The simulation conditions are parallel with an experimental work of one of the authors. The vortex in cell method, which was presented by the authors for flow simulations of two-layer density stratified fluid in a prior study, is used. The simulation favorably highlights the collision, deformation and penetration of the vortex ring at the density interface. It also successfully reveals the mixing between the upper and lower fluids induced by the motion of the vortex ring. These simulated results are discussed by comparing with the corresponding experimental ones.

DOI： 10.1299/jsmemecj.2017.s0520406

CiNii Research

Numerical Simulation of Mixing Process by Vortex Rings Launched into Two-Layer Density-Stratified Fluid

DEGAWA Tomohiro, Uchiyama Tomomi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2017 ( 0 ) page： S0520405 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

This study numerically investigates the mixing of a two-layer density stratified fluid caused by vortex rings. Initially, the density-stratified fluid is in a static condition in a tank. The upper and lower fluids are glycerol aqueous solution and an aqueous solution of potassium dihydrogen phosphate, respectively. Two vortex rings are arranged on a vertical line in the lower fluid, and the axial interval is 80 mm. The diameter of the vortex ring is 26.4 mm, and the Reynolds numbers based on the circulation are 4000, 6000, and 8000. The vortex rings are launched simultaneously in the vertically upward direction. The simulation explores the collision of the vortex rings with the density interface, the entrainment of the fluids into the vortex rings, and the resulting mixing between the fluids. It also clarifies the behavior of each vortex ring, such as the deformation and the interaction with the density interface.

DOI： 10.1299/jsmemecj.2017.s0520405

CiNii Research

Behavior of a jet issuing diagonally upward into two-layer density-stratified fluid in a cylindrical tank Reviewed

Degawa, T, Fukue, S, Uchiyama, T, Ishikawa, A, Motoyama, K

J. Flow Control, Measurement & Visualization Vol. 5 page： 51-64 2017

Generation and transport of solid particle clusters using a vortex ring launched into water Reviewed

Uchiyama, T, Yano, C, Degawa, T

Int. J. Chemical Engineering and Applications Vol. 8 ( 4 ) page： 253-260 2017

Development of Generation and Transport Technologies of Solid Particle Clusters Using a Vortex Ring

UCHIYAMA Tomomi

Hosokawa Powder Technology Foundation ANNUAL REPORT Vol. 25 ( 0 ) page： 26 - 32 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Hosokawa Powder Technology Foundation

The generation and transport of solid particle clusters by a vortex ring launched into quiescent water are explored. A vortex ring launcher, composed of a cylinder and a piston, is mounted at the bottom of a water tank. Polyacetal particles are placed on a mesh stretched near the cylinder outlet. The number of particles is 100, the mean diameter and density are 1.52 mm and 1417 kg/m3 respectively. The water in the cylinder is discharged vertically upward into the tank by the piston to launch the particle-laden vortex ring. Such two-phase flows of the Reynolds number Re based on the piston velocity and the cylinder diameter at 6500, 7500 and 13000 are investigated. The particles are entrained just after the launch of the vortex ring of Re = 7500 and 13000. The resultant particle cluster is transported by the convection of the vortex ring. The water velocity on the vertical cross-section of the vortex ring lessens due to the particles, resulting in the reduction of the circulation of the vortex ring. The reduction is larger for the lower Re.

DOI： 10.14356/hptf.15102

CiNii Research

A Feasibility Study of Power Generation from Sewage Using a Hollowed Pico-Hydraulic Turbine

Uchiyama Tomomi, Honda Satoshi, Okayama Tomoko, Degawa Tomohiro

ENGINEERING Vol. 2 ( 4 ) page： 510 - 517 2016.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Engineering

This study is concerned with the feasibility of power generation using a pico-hydraulic turbine from sewage flowing in pipes. First, the sewage flow rate at two connection points to the Toyogawa River-Basin Sewerage, Japan, was explored for over a year to elucidate the hydraulic energy potential of the sewage. Second, the performance of the pico-hydraulic turbine was investigated via laboratory experiments that supposed the turbine to be installed in the sewage pipe at the connection points. This study indicates that the connection points have hydraulic potential that can be used for power generation throughout the year. It also demonstrates that the pico-hydraulic turbine can be usefully employed for power generation from sewage flowing in the pipe at the connection points.

DOI： 10.1016/J.ENG.2016.04.007

Web of Science

Scopus

Numerical simulation of the interactions between a vortex ring and solid particles suspended above a horizontal wall

Uchiyama Tomomi, Shimada Seiji

POWDER TECHNOLOGY Vol. 301 page： 966 - 980 2016.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Powder Technology

The interactions between a vortex ring and solid particles near a horizontal wall in the air are explored in this study using numerical simulations. The vortex ring is moved toward the particles initially arranged in layers above the wall. The Reynolds number of the vortex ring is 1146. When the Stokes number St is 0.1, the particles initially arranged around the central axis of the vortex ring are driven toward the wall while moving in the radial direction. They distribute circularly along the outer edge of the particle cluster on the wall. The particles near the layer's edge are whirled up. Three-dimensional vortex structures, including secondary and tertiary vortex rings, are produced around the particles. When St = 1, vortical flows induced around the particles appear in the broader region. They reduce rapidly owing to the motion of particles relative to the wall (collision and rebound). The drag force acting on the particles lowers the strength of the vortex ring and also suppresses the approach of the vortex ring toward the wall.

DOI： 10.1016/j.powtec.2016.07.042

Web of Science

Scopus

Numerical simulation of flow around two tandem cylinders by vortex in cell method combined with immersed boundary method

Van Luc N., Zuhal L.R., Uchiyama T.

Advances and Applications in Fluid Mechanics Vol. 19 ( 4 ) page： 787 - 810 2016.10

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Advances and Applications in Fluid Mechanics

This study is concerned with the numerical simulation of incompressible flows around two circular cylinders in tandem arrangement. A vortex in cell (VIC) method combined with an immersed boundary (IB) method is applied to the simulation. The Reynolds number Re, based on the diameter D of cylinder and the flow velocity upstream of the front cylinder, ranges from 200 to 9500. The distance L between the cylinders is varied from 1.5D to 8D. The simulated flow characteristics, such as the behavior of the shear layers separated from the cylinders, the vortex shedding and the fluid forces acting on the cylinders, are favorably compared with the existing results. The simulation can also successfully analyze the effects of Re and L on the flow characteristics. These simulation results demonstrate that the VIC method combined with the IB method is usefully applicable to the simulation of incompressible flows around two tandem cylinders.

DOI： 10.17654/FM019040787

Scopus

Study of the interactions between rising air bubbles and vortex core of swirling water flow around vertical axis

Uchiyama Tomomi, Ishiguro Yukihiro

CHEMICAL ENGINEERING SCIENCE Vol. 142 page： 137 - 143 2016.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Chemical Engineering Science

The interactions between rising air bubbles and the vortex core of swirling water flows in a cylindrical tank are experimentally investigated. A stirring disc mounted at the center of the tank bottom is rotated to produce swirling water flows around the central (vertical) axis of the tank, and small air bubbles are successively released from tubules mounted near the stirring disc. The bubbles rise helically in the swirling water flow because of the buoyancy force, and some bubbles are entrained into the vortex core. The precessional amplitude of the vortex core is enhanced by the bubbles when the bubble flow rate Qg is very low. But it decreases with increasing Qg when Qg is larger than a certain value. In the horizontal cross-sections near the stirring disc, the bubbles make the water flow field nonaxisymmetric and reduce the water velocity. The water velocity variation due to the bubbles affects the shape of the vortex funnel formed at the water surface.

DOI： 10.1016/j.ces.2015.11.042

Web of Science

Scopus

Numerical Simulation of Mixing of Density-Stratified Fluid in a Cylindrical Tank by a Diagonal Jet

UCHIYAMA Tomomi, AOZASA Isao, ISHIKAWA Akira, MOTOYAMA Kouji

The Proceedings of the Fluids engineering conference Vol. 2016 ( 0 ) page： 0207 2016

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

Mixing phenomena, induced by a jet issued diagonally upward into a two-layer densitystratified fluid in a cylindrical tank, are numerically simulated. The upper and lower fluids are water and a NaCl aqueous solution, respectively. The mass concentration of the NaCl-water solution is 0.02. The lower fluid is issued from a nozzle mounted on the tank bottom. The angle of the nozzle to the tank bottom is 60 degree, and the Reynolds number defined by the jet velocity and the nozzle diameter ranges from 475 to 3089. The simulation highlights the jet behavior relative to the density interface and the resultant mixing phenomena.

DOI： 10.1299/jsmefed.2016.0207

CiNii Research

Study of the interactions between rising air bubbles and vortex core of swirling water flow around vertical axis Reviewed

Uchiyama, T, Ishiguro, Y

Chemical Engineering Science Vol. 142 page： 137-143 2016

SIMULATION OF JET ISSUED INTO TWO-LAYER DENSITY-STRATIFIED FLUID BY VORTEX IN CELL METHOD COMBINED WITH IMMERSED BOUNDARY METHOD

Aozasa, I; Uchiyama, T

PROCEEDINGS OF THE ASME/JSME/KSME JOINT FLUIDS ENGINEERING CONFERENCE, 2015, VOL 1A, SYMPOSIA, PT 2 2016

Numerical simulation of the interactions between a vortex ring and solid particles suspended above a horizontal wall Reviewed

Uchiyama, T, Shimada, S

Powder Technology Vol. 301 page： 966-980 2016

Experimental study of flow around a circular cylinder inside a bubble plume Reviewed

Uchiyama, T, Ishiguro, Y

Advances in Chem. Eng. Sci. Vol. 6 page： 269-280 2016

Effects of clearance between rotor and ground on the performance of an open cross-flow-type nano-hydraulic turbine Reviewed

Uchiyama, T, Mizoguchi, S, Iio, S, Katayama, Y, Ikeda, T

J. Energy and Power Engineering Vol. 10 page： 465-473 2016

Accuracy analysis of the Lattice Boltzmann equation method for the Cahn-Hilliard equation

SETA Takeshi, UCHIYAMA Tomomi, TAKANO Noboru

The Proceedings of The Computational Mechanics Conference Vol. 2016.29 ( 0 ) page： 050 2016

A feasibility study of power generation from sewage using a hollowed pico-hydraulic turbine Reviewed

Uchiyama, T, Honda, T, Okayama, T, Degawa, T

Engineering Vol. 2 page： 510-517 2016

　 PREV - NEXT 　

<UCHIYAMA, Tomomi>

Papers - UCHIYAMA, Tomomi