Papers - Obi, Shinnosuke

弾性変形する平板の形状と自己推進速度に関する実験的研究

池田曉， 馬場直道， 小尾晋之介

流体工学部門講演会講演論文集 2018, OS13-7  2018

Measurement of the fluctuating pressure on the shroud wall of a hard-disk drive model

Sonoda Y., Sanada K., Obi S.

TURBULENCE HEAT AND MASS TRANSFER 9 (THMT-18) (Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer)  2018-July   689 - 698 2018

ISSN  2377-2816

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The present study aims at clarifying the turbulent structure developing in a hard disk drive through the measurement of fluctuating pressure on the shroud wall. The measurements have been conducted in two different models, with and without read-write arms, and the results are compared to characterize the effect of the internal structure of turbulent flow on the device. The effect of read-write arms is found to be of primary importance, as it changes the flow structure drastically, with the increasing the arm insertion angle. The most pronounced effect has been found in the gradual change of the characteristic frequency in the power spectrum density of the pressure fluctuation: Both qualitative and quantitative changes are observed.

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Development of a Mechanical Engineering Test Item Bank to promote learning outcomes-based education in Japanese and Indonesian higher education institutions

Jeffrey S. Cross, Estiyanti Ekawati, Satoko Fukahori, Shinnosuke Obi, Yugo Saito, Nathanael P. Tandian, and Farid Triawan

Tuning Journal for Higher Education (University of Deusto)  5 ( 1 ) 41 - 73 2017.11

Research paper (scientific journal), Joint Work, Accepted,  ISSN  2340-8170

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Following on the 2008-2012 OECD Assessment of Higher Education Learning Outcomes (AHELO) feasibility study of civil engineering, in Japan a mechanical engineering learning outcomes assessment working group was established within the National Institute of Education Research (NIER), which became the Tuning National Center for Japan. The purpose of the project is to develop among engineering faculty members, common understandings of engineering learning outcomes, through the collaborative process of test item development, scoring, and sharing of results. By substantiating abstract level learning outcomes into concrete level learning outcomes that are attainable and assessable, and through measuring and comparing the students’ achievement of learning outcomes, it is anticipated that faculty members will be able to draw practical implications for educational improvement at the program and course levels. The development of a mechanical engineering test item bank began with testscale test implementation in 2016 of 348 first semester master’s students in 9
institutions in Japan, using both multiple choice questions designed to measure the
mastery of basic and engineering sciences, and a constructive response task designed
to measure “how well students can think like an engineer.” The same set of test items
were translated from Japanese into to English and Indonesian, and used to measure
achievement of learning outcomes at Indonesia’s Institut Teknologi Bandung (ITB)
on 37 rising fourth year undergraduate students. This paper highlights how learning
outcomes assessment can effectively facilitate learning outcomes-based education, by
documenting the experience of Japanese and Indonesian mechanical engineering
faculty members engaged in the NIER Test Item Bank project.

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A smooth partition of unity finite element method for vortex particle regularization

KIRCHHART MATTHIAS, OBI SHINNOSUKE

SIAM Journal of Scientific Computing (SIAM Journal on Scientific Computing)  39 ( 5 ) A2345 - A2364 2017.10

Research paper (scientific journal), Joint Work, Accepted,  ISSN  10648275

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We present a new class of C∞-smooth finite element spaces on Cartesian grids, based on a partition of unity approach. We use these spaces to construct smooth approximations of particle fields, i.e., finite sums of weighted Dirac deltas. In order to use the spaces on general domains, we propose a fictitious domain formulation, together with a new high-order accurate stabilization. Stability, convergence, and conservation properties of the scheme are established. Numerical experiments confirm the analysis and show that the Cartesian grid-size should be taken proportional to the square-root of the particle spacing h, resulting in significant speed-ups in vortex methods.

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A Splitting-free Vorticity Redistribution Method

KIRCHHART MATTHIAS, OBI SHINNOSUKE

Journal of Computational Physics (Elsevier)  330   282 - 295 2017.02

Research paper (scientific journal), Joint Work,  ISSN  0021--9991

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We present a splitting-free variant of the vorticity redistribution method. Spatial consis-tency and stability when combined with a time-stepping scheme are proven. We propose a new strategy preventing excessive growth in the number of particles while retaining the order of consistency. The novel concept of small neighbourhoods significantly reduces the method’s computational cost. In numerical experiments the method showed second order convergence, one order higher than predicted by the analysis. Compared to the fast multipole code used in the velocity computation, the method is about three times faster.

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Internal Regulation to Promote Internationalization of University

OBI SHINNOSUKE

KEIO SFC JOURNAL (慶應義塾大学湘南藤沢学会)  17 ( 2 ) 6 - 11 2017

Single Work

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It is of great importance for universities to introduce internal regulations which allow flexible student mobility when the promotion of internationalization is considered. Through the activity of EBA Consortium, a new status for
international student has been settled, so that students can come and leave at any time regardless of the academic calendar. For Japanese students to leave during the study at the university, the problems due to discrepancy in academic calendar could be partially resolved by introducing four-term system. The appropriate design of such regulation should be conducted in accordance with the global picture of the academic activities in consortium to avoid local optimization.

Flow Control over Swept Wings Using Nanosecond-pulse Plasma Actuator

KATO KENTARO, BEREITSAMTER CHRISTIAN, OBI SHINNOSUKE

International Journal of Heat and Fluid Flow (Elsevier)  61, PartA   58 - 67 2016.10

Research paper (scientific journal), Joint Work,  ISSN  0142-727X

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An experimental study aiming at lift enhancement of a swept wing by using a plasma actuation driven by repetitive nanosecond-pulse voltage was carried out. The periodic plasma actuation was applied near the apex in order to manipulate the leading edge vortices in the post-stall regime.The velocity field in the wake was measured by means of stereoscopic particle image velocimetry and was evaluated based on control volume analysis. The results indicated that the change in the intensity of the streamwise vortex led to the lift enhancement.

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HDD 内乱流場におかれたアームに作用する流体力の数値シミュレーション

田丸明裕， 小尾晋之介

IIP 情報・知能・精密機器部門講演会講演論文集 2016, B-1-2  2016

1E43 動脈瘤治療を目的としたパイプラインステントの流動解析

小尾晋之介， 立嶋智

バイオエンジニアリング講演会講演論文集 2016.28, _1E43-1_-_1E43-5_  2016

HDD モデル内壁面における変動圧力計測

正本佳， 中村庸義， 小尾晋之介

IIP 情報・知能・精密機器部門講演会講演論文集 2016, B-1-1  2016

Evaluation of Pressure Field Based on the Velocity Measurement by PIV

OBI SHINNOSUKE

Turbomachinery (Turbomachinery Society of Japan)  43 ( 11 ) 686 - 691 2015.11

Research paper (scientific journal), Single Work

Space-time pressure-velocity correlations in a turbulent boundary layer

NAKA YOSHITSUGU, STANISLAS MICHEL, FOUCAUT JEAN-MARC, COUDERT SEBASTIEN, LAVAL JEAN-PHILIPPE, OBI SHINNOSUKE

Journal of Fluid Mechanics (Cambridge University Press)  771   624 - 675 2015.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00221120

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The spatio-temporal pressure-velocity correlation in a turbulent boundary layer is investigated to try to understand the link between pressure uctuations and turbulent coherent structures. A new experimental setup is developed to measure the pressure fluctuations at the wall and in the field, and the velocityfield by stereo PIV simultaneously. For the pressure fluctuations in the field, the pressure-velocity correlations Rpu and Rpw exhibit a meaningful correlation in a region extended in time in addition to the structures observed with the wall pressure. The structure of the diffrent correlations observed can be linked to the LSM and VLSM put previoulsly in evidence by diffrent authors.

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PIV 速度データに基づく圧力場の推定方法 (特集 光応用計測の Cutting Edge)

小尾晋之介

ターボ機械 43 (11), 686-691  2015

0201 半円オリフィス管内乱流のステレオ PIV 計測及び壁面静圧計測

安岡佳紀， 小尾晋之介

流体工学部門講演会講演論文集 2015, _0201-1_-_0201-3_  2015

11017 半円オリフィス管内乱流のステレオ PIV 計測

小尾晋之介， 安岡佳紀

日本機械学会関東支部総会講演会講演論文集 2015.21, _11017-1_-_11017-2_  2015

11001 平板往復運動の誘起する渦流れ構造と力の渦法による数値解析

国井悠介， 日置史記， 小尾晋之介

日本機械学会関東支部総会講演会講演論文集 2015.21, _11001-1_-_11001-2_  2015

0702 移動平板の誘起する渦流れ構造と力の渦法による数値解析

國井悠介， 日置史紀， 小尾晋之介

流体工学部門講演会講演論文集 2015, _0702-1_-_0702-5_  2015

0616 ナノ秒パルスプラズマアクチュエータを用いた翼上の流れ制御のための数値モデル

加藤賢太郎， 小尾晋之介

流体工学部門講演会講演論文集 2015, _0616-1_-_0616-3_  2015

LES study of the turbulent flow in a HDD model

Tamaru A., Obi S.

Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer (Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer)  0   859 - 862 2015

ISSN  26425629

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Turbulent flow in a hard disk drive model which contained two disks and a RW (read-and-write) arm was numerically analyzed at a disk rotation Reynolds number of about 105. The evaluation of the fluctuating torque revealed that the RW arm may be oscillated at a frequency which had only weak correlation with the disk rotation speed. The fluctuating pressure was stronger on the leeward surface of the RW than that of the windward. It was further indicated that the fluctuating torque on the RW arm was weakly correlated with the surface pressure fluctuation on the shroud wall.

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Three-dimensional turbulent recirculating flow in a pipe with semi-circular orifice

Yasuoka Y., Obi S.

Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer (Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer)  0   203 - 206 2015

ISSN  26425629

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Experimental study on the turbulent flow in a circular pipe with a semi-circular orifice has been conducted. The velocity was measured by a stereo PIV system that provided the three components of mean velocity in as well as six components of the Reynolds stress on the cross section of the pipe at different streamwise locations. The oncoming flow was confirmed to be a typical fully developed turbulent flow. The flow behind the semi-circular orifice was found to be strongly turbulent, associated with secondary flow. The ambiguity in the experiments was carefully addressed, and it was found that the measurement conducted either with or without the orifice was found to be equally accurate.

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