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Dive into the research topics where Hisashi Minakuchi is active.

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Featured researches published by Hisashi Minakuchi.


International Journal of Materials & Product Technology | 2005

A three-dimensional numerical study of Marangoni convection in a floating full zone

Hisashi Minakuchi; Yasunori Okano; Sadik Dost

The article presents a three-dimensional computational study for the transport phenomena occurring during the growth of Si-doped Ge crystals by the Floating-Zone (FZ) technique. Numerical simulations were performed to examine the role of the Marangoni convection in a Full-zone configuration under zero gravity. The effects of crystal rotation and zone aspect ratio were also considered in the model. The field equations of the liquid phase and the associated boundary conditions were discretised by the finite difference method, and solved by the HSMAC (Highly Simplified Marker And Cell) method. Results show that the flow and temperature fields are initially two-dimensional with two pairs of vortexes of the same size, as time proceeds, however the flow field becomes three-dimensional in spite of assumed axisymmetric boundary conditions. The concentration field becomes three-dimensional much earlier than the flow field. The float zone aspect ratio has a prominent effect on the critical Marangoni number at which three-dimensional flow structures occur, and as well as on the azimuthal wave number and the uniformity of the solute concentration along the crystal growth interface in the melt. It was also shown that the application of a crystal rotation is very beneficial in obtaining a moreuniform solute concentration distribution along the growth interface.


International Conference on Global Research and Education | 2018

The Numerical Study of Co-existence Effect of Thermal and Solutal Marangoni Convections in a Liquid Bridge

Chihao Jin; Atsushi Sekimoto; Yasunori Okano; Hisashi Minakuchi

Marangoni convection is a flow along the interface between two fluids due to the variation of surface tension, which is mainly caused by temperature and/or concentration gradients, namely thermal and/or solutal Marangoni convection(s). During the crystal growth by the floating zone method, Marangoni convection may induce the striation and affect the quality of growing crystal. Therefore, it is necessary to understand the convective phenomenon and control it. In this study, a three-dimensional configuration of the half-zone liquid bridge in the crystal growth of SixGe1-x was selected by establishing the temperature and concentration differences. The equations of continuity, momentum, energy and mass transfer were solved by the PISO algorithm in the OpenFOAM. Thermal and solutal Marangoni convections were set to flow in the opposite direction under zero gravity in the melt with different Marangoni numbers. Results have shown that when MaC is larger than −MaT, the flow is steady and axisymmetric, while MaC is smaller than −MaT, the flow is unsteady and irregular. As for the control of Marangoni convection, rotation of top and bottom plane in the liquid bridge was applied during the crystal growth. With different rotation speeds and directions, the suppression of Marangoni convection can be effectively realized by the appropriate forced rotation.


Journal of Crystal Growth | 2014

The relative contributions of thermo-solutal Marangoni convections on flow patterns in a liquid bridge

Hisashi Minakuchi; Youhei Takagi; Yasunori Okano; Satoru Gima; Sadik Dost


Journal of Crystal Growth | 2014

Combined effect of crucible rotation and magnetic field on hydrothermal wave

Youhei Takagi; Yasunori Okano; Hisashi Minakuchi; Sadik Dost


Desalination and Water Treatment | 2010

Double-sided wet fabric evaporator utilizing wind and solar energy efficiently — Simulation modeling and feasibility of evaporator

Takehiro Nosoko; Satoru Gima; Hisashi Minakuchi; K. Ameku; K. Irabu


Journal of Crystal Growth | 2017

Effect of thermo-solutal Marangoni convection on the azimuthal wave number in a liquid bridge

Hisashi Minakuchi; Yasunori Okano; Sadik Dost


Transactions of The Japan Society for Aeronautical and Space Sciences, Space Technology Japan | 2012

Three-dimensional Numerical Simulation of Thermal and Solutal Marangoni Convection in a Liquid Bridge under Zero-gravity Field

Hisashi Minakuchi; Youhei Takagi; Yasunori Okano; Takehiro Nosoko; Satoru Gima; Sadik Dost


THMT-12. Proceedings of the Seventh International Symposium On Turbulence, Heat and Mass Transfer Palermo, Italy, 24-27 September, 2012 | 2012

A Numerical study of oscillatory thermo-solutal Marangoni convection in a floating half zone

Hisashi Minakuchi; Youhei Takagi; Yasunori Okano; Satoru Gima; Sadik Dost


International Communications in Heat and Mass Transfer | 2011

Double-sided wet fabric evaporator utilizing wind and solar energy efficiently — One-dimensional transient simulations

Takehiro Nosoko; K. Ameku; Hisashi Minakuchi


The Proceedings of The Computational Mechanics Conference | 2015

096 The alternate effects of thermal and solutal Marangoni convection on flow patterns in a half zone liquid bridge

Koki Nishime; Tatsuya Yoshino; Hisashi Minakuchi; Yasunori Okano

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Satoru Gima

University of the Ryukyus

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Sadik Dost

University of Victoria

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Takehiro Nosoko

University of the Ryukyus

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K. Ameku

University of the Ryukyus

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