Graduate School of Science and Engineering（Engineering）
理工学専攻（機械工学）
日本語
Update date：2024/12/25
Professor
Iwamoto Yukiharu

Research History

  1. 2000- 愛媛大学
  2. 2000- Ehime university

Education

  1. Osaka University1991/041995/03graduated
  2. Osaka University1995/041997/03completed
  3. Osaka University1997/042000/03withdrawn after completion of required course credits

Degree

  1. Doctor of Engineering, Ph. D.システム人間系Osaka University2001/03/23
  2. Master of Engineering物理系大阪大学
  3. Ph.D.大阪大学
  4. 博士(工学)大阪大学

Licenses and Qualifications

  1. 衛生工学衛生管理者2004/11/16

Research Areas

Research Interests

  1. Pipings
  2. 配管要素

Research Projects

  1. Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific ResearchDevelopment of a device for measuring small hydro power resourcesGrant-in-Aid for Scientific Research (C)2013/04-2016/03We developed a device that measured a flow velocity in a water channel by an acceleration sensor built in a smartphone, utilizing a property that an obstacle immersed in a flow vibrates with frequencies proportional to flow velocities. We found that a small flat plate as an obstacle with a width, height and thickness of 18, 54 and 1mm, respectively, had the proportional relationship under flow velocities between 0.3 and 1 m/s. We also made an application that adopted the maximum entropy method as a fast Fourier transform showing quick response．We tested our prototype device in an actual water channel and found that the errors compared with outputs of electromagnetic flow meter were within 10%.
  2. Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific ResearchDrag Reducing Effect of Surfactant Solution on a Piping System and its Application for Saving Energy ConsumptionGrant-in-Aid for Scientific Research (C)2005-2007The purpose of our project is to clarify the flow mechanism of surfactant solution, which exhibits drastic drag reduction in a piping system. 'lb achieve this purpose, we made the experimental apparatus containing a straight circular cross sectional pipe and the bend with the curvature ratio (bend curvature divided by inner radius of pipe) of four, and conducted the investigation of rheological characteristics, pressure measurement, and WV measurement. Finally, we fried to explain the drug reducing effect relating with those results. These would to be valuable for an innovation of the new drug reduction technique. The result of the rheological characteristics investigation showed that our examining surfactant solution (LSP-01M) could also become the shear induced state(SIS)that was common in many surfactant solutions. In the experiment using a straight pipe, the developing process of the boundary layer was clarified in the case of surfactant solution. We also showed that the maximum drug reduction ratio exceeded over 70%, and that drug reduction effect did not completely disappear in the case of weight concentration of 50 ppm when increasing Reynolds number. The velocity distribution in the wall coordinate system was also provided. Velocity measurement were carried out in detail, and it was hind that the Reynolds shear stress, which is correlation of axial and radial velocity fluctuations, were suppressed by malting the symmetric distribution of the probability density function against outward interaction and ejection, inward interaction and sweep, respectively. It was also found that the apparent viscosity slightly apart from the wall coincided with that of SIS, and there was the region with smaller apparent viscosity adjacent to the wall. We explained the reason of suppression of Reynolds shear stress, utilizing this gradient of apparent viscosity. In the experiment using the bend, it was found that the disturbance induced by the bend could not vanish easily in the case of strong drag reduction, and that the existence of two regions with high and low velocities lasted until they made strong shear. We also found that there was little disturbance in the outer part of the bend.
  3. Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific ResearchSelf-sustaining mechanisms of near-wall turbulenceGrant-in-Aid for Scientific Research (C)1998-2000In this research, we make both experimental and theoretical approaches to the self-sustaining mechanisms of near-wall turbulence. In the experiments, the generation mechanism of Reynolds stresses, which play a significant role in maintenance of turbulence activity, has been demonstrated based upon the results obtained from turbulence measurement of a square-duct flow using LDV.In the near-wall region of the duct, streamwise vortical motions induce the ejection and the sweep, both of which generate intense Reynolds stresses, so that turbulence is sustained. In the corner region of the duct, on the other hand, streamwise vortices transport fluid momentum from one wall to another adjacent wall, which leads to the reduction of the contribution of the sweep. In this region, therefore, turbulence is sustained principally through the ejection. The characteristics of the streamwise vortices, e.g. dimension and circulation on cross-flow plane, are shown in the corner region. In addition, the spatial distribution of local wall shear stress on the wall is presented. In the theoretical investigation, the generation mechanism of streamwise vortices, which induce the Reynolds stress responsible for the maintenance of turbulence, has been demonstrated. The hydrodynamic instability of near-wall streaks is investigated to prove that streaks are unstable to sinuous (or bending) disturbances. Because streaks are affected by a shearing motion across the wall-normal direction, the unstable mode for streaks has the inclination from the wall-normal direction in the streamwise direction, which means that if streaks are bent in the spanwise direction, through the instability, the streamwise vorticity is directly generated to consequently involve the streamwise vortices. In addition to the above analysis, the direct, numerical simulations of a minimal plane Couette flow (i.e. minimal flow units of near-wall turbulence) have been performed to obtain time-periodic solutions to the Navier-Stokes equation, which well represent the whole of the self-sustaining cycle in near-wall turbulence (in preparation for publication). We have numerically shown the dominant role in turbulence of coherent structures consisting of streamwise streaks and vortices.
View details...

Papers

  1. Impact of reconstructed portal vein morphology on postoperative nutritional status in pancreatoduodenectomy: a computational fluid dynamics study.2024/07/30Katsunori Sakamoto Yukiharu Iwamoto Kohei Ogawa Oğuzhan Şal Kei Tamura Takahiro Hikida Chihiro Ito Miku Iwata Akimasa Sakamoto Mikiya Shine Yusuke Nishi Mio Uraoka Tomoyuki Nagaoka Masahiko Honjo Naotake Funamizu Yasutsugu TakadaSurgery todayResearch paper (scientific journal)10.1007/s00595-024-02903-0This study evaluated the impact of reconstructed portal vein/superior mesenteric vein (PV/SMV) morphology on the long-term nutritional status following pancreatoduodenectomy (PD) using computational fluid dynamics (CFD). Twenty-four patients who underwent PD with PV/SMV resection and reconstruction without tumor recurrence for over 9 months after the operation were enrolled in the study. Three-dimensional models were constructed from computed tomography images obtained 3-6 months postoperatively. The pressure (p) at the inlet and turbulence dissipation rate (ε) at the outlet were investigated in the models. Patients with values of either p or ε above the upper interquartile range were classified as the poor flow group. The prognostic nutritional index improvement rate was significantly lower at 9 postoperative months in the poor flow group than in the good flow group (P = 0.016). This finding indicates the utility of a CFD analysis for evaluating the reconstructed PV/SMV morphology.
  2. Impact of the inferior vena cava morphology on fluid dynamics of the hepatic veins.2023/07/29Katsunori Sakamoto Yukiharu Iwamoto Kohei Ogawa Kei Tamura Chihiro Ito Miku Iwata Akimasa Sakamoto Mikiya Shine Yusuke Nishi Mio Uraoka Tomoyuki Nagaoka Masahiko Honjo Naotake Funamizu Yasutsugu TakadaSurgery todayResearch paper (scientific journal)10.1007/s00595-023-02733-6We reported previously that a large vertical interval between the hepatic segment of the inferior vena cava (IVC) and right atrium (RA), referred to as the IVC-RA gap, was associated with more intraoperative bleeding during hemi-hepatectomy. We conducted a computational fluid dynamics (CFD) study to clarify the impact of fluid dynamics resulting from morphologic variations around the liver. The subjects were 10 patients/donors with a large IVC-RA gap and 10 patients/donors with a small IVC-RA gap. Three-dimensional reconstructions of the IVC and hepatic vessels were created from CT images for the CFD study. Median pressure in the middle hepatic vein was significantly higher in the large-gap group than in the small-gap group (P = 0.008). Differences in hepatic vein pressure caused by morphologic variation in the IVC might be one of the mechanisms of intraoperative bleeding from the hepatic veins.
  3. Unification venoplasty during two versus one venous reconstruction: Computational fluid dynamics study.2022/11/19Katsunori Sakamoto Yukiharu Iwamoto Kohei Ogawa Kei Tamura Yusuke Nishi Mio Uraoka Tomoyuki Nagaoka Masahiko Honjo Naotake Funamizu Yasutsugu TakadaJournal of hepato-biliary-pancreatic sciences30/ 6, e31-e35Research paper (scientific journal)10.1002/jhbp.1280Two versus 1 venous reconstruction is sometimes required for Hepato-Biliary-Pancreatic and Transplantation surgery. V-shape venoplasty is considered to be useful knack of unification method during 2 versus 1 venous reconstruction in clinical practice. The usefulness of V-shape unification venoplasty was proven by the present computational fluid dynamics study.
  4. A New Diamond Chemical Vapor Deposition Method on Steel Surface2022/08/20SHIRAISHI Ryoya TOYOTA Hiromichi ZHU Xia MATSUMOTO Kengo NOMURA Shinfuku IWAMOTO YukiharuJournal of the Japan Institute of Energy101/ 8, 147-151Research paper (scientific journal)10.3775/jie.101.147The Japan Institute of EnergySteel coated with diamond film is excellent material specifically for cutting tools. However, direct diamond deposition has been considered difficult. In the present study, a stainless steel surface was mechanically processed to directly deposit diamond on it. Diamond film was rarely obtained when the steel surface was rasped with sandpaper, metal file, or ground with a flat drill. In most cases, amorphous carbon was deposited on the surface. On the other hand, high-quality diamond was often deposited when regularly arranged pits were created on the surface using a drill. In this case, the diamond was deposited on the lips of the pits and the flat (nonprocessed) areas between (rather than on the inside of) the pits. The quality of diamond film obtained in the present work is the best reported for direct diamond chemical vapor deposition (CVD) on steel. It is an important discovery that high-quality diamond film can be directly deposited on steel surfaces via simple mechanical surface processing without interlayer or seeding.
  5. Enzyme-free saccharification of cellulose to glucose using ultrasonic welding2022/02Shinfuku Nomura Taiki Murase Takeru Kodama Shinobu Mukasa Yukiharu IwamotoInternational Journal of Thermofluids13Research paper (scientific journal)10.1016/j.ijft.2022.100137Ultrasonic welding is a processing technology that can instantly fuse and join thermoplastic resins by applying minute amounts of ultrasonic vibration and pressure. The present study demonstrates that the frictional force or pressure caused by ultrasonic welding can cause cellulose decomposition without a saccharifying enzyme or catalysts. Ultrasonic waves of 19.5 kHz were irradiated downward on samples using a horn-type transducer. The cellulose specimens were composed of 15 – 105 stacked sheets of filter paper with high cellulose content, a sheet of cotton, and a sheet of hemp. The high frictional forces resulting from direct contact of cellulose with the ultrasonic horn tips decomposed the saccharides within a short time to produce glucose. Cellulose is decomposed into glucose through hydrolysis in an enzyme-free environment by ultrasonic irradiation, but then it is further decomposed into 5-hydroxymethylfurfural, furfural, and other compounds via a dehydration reaction caused by an increase in temperature of the reaction field from continuous ultrasonic irradiation. Glucose could be obtained from the cellulose without using an enzyme through ultrasonic welding. The result of decomposing cellulose, cotton, and hemp by this method revealed that a yield of 1.2% glucose could be obtained by decomposing filter paper.
View details...

Presentations

  1. B-スプラインを用いたベイズ形状最適化による 流れの効率化2024年度日本付加製造学会講演会2024/12/06Oral presentation(invited, special)Overview of Bayesian shape optimization using the control point coordinates of B-spline surfaces as the determining variable
  2. 配管バルブの形状最適化とその結果を洞察するための流れ場のクラスタリング日本流体力学会年会20242024/09/26Oral presentation(general)
  3. Study on Flow Fields Clustering around Diamond-Shaped Cylinder GroupsJSME annual meeting 20242024/09/09Oral presentation(general)
  4. Analyses of Flow Fields in Diamond-Shaped Cylinder Bundles by Flow Field Clustering Technique日本機械学会 中国四国支部 第61期総会・講演会2023/03/03Oral presentation(general)
  5. Effects of a Guide Vane Having Cutouts in a Flow within a Square Section Bend日本機械学会 中国四国支部 第61期総会・講演会2023/03/03Oral presentation(general)
View details...

Industrial Property Rights

  1. Patent吸引装置特願2014-1464712014/07/17特開2016-0220262016/02/08
View details...

Awards

  1. 2021/03Chugoku-Shikoku Branch Award "Technology Award"100MPa級高圧ジェット水対応防護服の開発
  2. 2015/11The Sixth Monodzukuri Nippon Grand Award廃家電等のミックスプラスチックを材料毎に高速且つ高精度に選別可能とする装置の開発
View details...

Allotted Class

  1. 2024Exercise in Fluid Mechanics
  2. 2024Differential and Integral Calculus I
  3. 2024Sensing and Applications
  4. 2024Advanced Energy Conversion Engineering XII
  5. 2024Sensing and Applications
View details...

Media Coverage

  1. Professional skills to drink up all the corn in a canTV or radio programTokyo Broadcasting System TelevisionWhat's the difference?2016/02/28
View details...

Professional Memberships

  1. The Japanese Society for Multiphase Flow
  2. Atomic Energy Society of Japan
  3. The Japan Society of Fluid Dynamics
  4. 日本機械学会
  5. 日本ガスタービン学会
View details...

Committee Memberships

  1. 2024/08-2025/07The Japanese Society for Multiphase FlowCouncilor
  2. 2019/04-presentThe Japan Society of Fluid Mechanicseditorial committee member of journal Nagare
  3. 2016/08-2018/08日本混相流学会評議員
  4. 2015/04-2016/03日本機械学会熱工学コンファレンス委員会委員
  5. 2013/04-2014/03日本流体力学会代議員
View details...