Curriculum Vitaes
Profile Information
- Affiliation
- Professor of Emeritus, Institute of Space and Astronautical Science, Japan Aerospace Exploration AgencyVisiting Professor, Tokyo University of Science
- Degree
- Doctor of Engineering(The University of Tokyo)
- Contact information
- fujii
rs.tus.ac.jp
- Other name(s) (e.g. nickname)
- Ko Fujii
- J-GLOBAL ID
- 200901042342169670
- researchmap Member ID
- 1000144496
- External link
Major Research Interests
4Research Areas
2Research History
19-
Apr, 2015 - Present
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Apr, 2015 - Sep, 2023
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Apr, 2013 - Mar, 2015
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Oct, 2003 - Mar, 2015
Education
2Committee Memberships
14-
Oct, 2020 - Sep, 2026
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Jul, 2016 - Jul, 2024
Awards
32-
Jun, 2023
Papers
433-
Flow, Turbulence and Combustion, Jul 2, 2025 Peer-reviewedInvitedLead author<jats:title>Abstract</jats:title> <jats:p>Scale-resolving simulations possess considerable benefits over modeled approaches because of their ability to access the underlying nonlinear fluid dynamics, and thus to predict not only the correct phenomenology, but also to generate insights on strategies to mitigate or eliminate undesirable features. The expense of resolving all pertinent turbulent scales becomes prohibitive however, as the size of the problem, typically measured by the Reynolds number based on a suitable set of reference parameters, becomes large, as is the case with flows of industrial interest such as full aircraft or their complex subsystems. This paper provides an assessment of scale-resolving methods, including some of the main benefits as well as barriers for use on large problems, together with a perspective on historical and recent trends that appear promising in the quest for routine industrial use. The factors that constitute the biggest hurdles to achieving acceptable wall-clock times and costs include meshing of complicated geometries, numerical schemes that are robust as well as accurate, suitable initial and boundary conditions, economical yet appropriate representation of near-wall turbulence, code parallelism, scalability and portability, and post-processing of the resulting big datasets. Considerations for these interrelated aspects are highlighted in the context of several 3D problems of increasing complexity, from wing sections without and with sweep, to aircraft wakes, propulsion subsystems, scramjet flowpaths and finally, full aircraft including empennages. Collectively, these examples feature the benefits of scale-resolving simulations. An illustrative approach that has reached a relatively high level of maturity using automatic mesh generation, a non-dissipative yet robust scheme, wall-modeling of turbulence, superior scalability and requiring little user intervention beyond providing the surface model, is used to demonstrate the potential of scale-resolving simulations for industry, achievable at modest cost and in reasonable wall-clock time.</jats:p>
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IEEE Access, 13 39631-39649, 2025 Peer-reviewed
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Proceedings of the Cambridge Unsteady Flow Symposium 2024, 257-271, Dec 3, 2024 Peer-reviewedInvited
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Aerospace, 11(11) 866-866, Oct 22, 2024 Peer-reviewedThe advancement of Arrival MANager (AMAN) is crucial for addressing the increasing complexity and demand of modern airspace. This study evaluates the operational feasibility and effectiveness of an innovative AMAN designed for en route airspace, the so-called En Route AMAN. The En Route AMAN functions as a controller support system, facilitating the sharing of information between en route air traffic controllers (ATCos), approach controllers (current AMAN), and airport controllers (Departure Managers) in airports with multiple runways. The En Route AMAN aims to support upstream ATCos by sequencing and spacing of incoming streams via speed control and runway assignment, thereby enhancing overall air traffic efficiency. Human-In-The-Loop simulations involving rated ATCos are performed under scenarios that replicate real-world traffic and weather conditions. These simulations focus on upstream airspace to assess the impact of En Route AMAN on delay mitigation and ATCos’ performance. Unlike previous studies that solely relied on theoretical models and fast-time simulation for operational feasibility evaluation, this approach incorporates ATCos’ real-time decision-making, situational awareness, and task management, addressing critical operationalization challenges. The results demonstrated that the En Route AMAN could reduce the average flight duration by up to 25.6 s and decrease the total number of ATCo instructions by up to 20% during peak traffic volume. These findings support that the En Route AMAN is both operationally viable and effective in mitigating arrival delays, highlighting the importance of Human-In-The-Loop for practical validation.
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AIAA SCITECH 2024 Forum, Jan 4, 2024
Misc.
191-
ターボ機械, 42(5) 297-304, May, 2014
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45 9p, Apr 10, 2014
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日本機械学会流体工学部門講演会講演論文集(CD-ROM), 2014 (Web), 2014
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流体力学講演会/航空宇宙数値シミュレーション技術シンポジウム講演集(CD-ROM), 46th-32nd ROMBUNNO.1D11, 2014
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数値流体力学シンポジウム講演論文集(CD-ROM), 28th ROMBUNNO.E02-4, 2014
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Fluids engineering conference ..., 2013 "0634-01"-"0634-05", Nov 9, 2013In this study, multiobjective design exploration for a rocket launch site is conducted using evolutionary computation with large eddy simulation to understand the acoustic characteristics associated with various launch sites. The launch site is described by curved surface. The flat plate inclined with 45 degree is considered as the reference configuration. The objective functions of multiobjective aero-acoustic design optimization are, 1) minimization of averaged sound pressure level near the payload fairing, 2) minimization of maximum pressure on the curved surface of the rocket launch site, and 3) minimization of the change of the curved surface from the reference configuration. Three-dimensional compressible Navier-Stokes equations are solved with the modified weighted compact nonlinear scheme. The total number of evaluation is 2500, and the evaluation of one generation necessitates the use of 6500 nodes using "K" supercomputer. As the results of the flow field analysis of some characteristic non-dominated solutions show the characteristics of acoustic wave and the location of the maximum gradient of the curved surface.
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Fluids engineering conference ..., 2013 "G0405-01"-"G0405-05", Nov 9, 2013This paper studied control of separated flow over an NACA0015 airfoil by a single dielectric barrier discharge (DBD) plasma actuator installed at the leading edge using large-eddy simulations with high-order accurate and high-resolution numerical scheme. A chord-based Reynolds number of 260,000 and an angle of attack of 18.8 degrees were considered. A phenomenological DBD plasma-actuator model was employed to provide the spatial body force distribution. The unsteady operation so-called a burst mode actuation was introduced and two burst frequencies of 1 and 6 with constant burst ratio of 0.1 were analyzed. Effects of the burst frequency on flow control performance were discussed in detail. Results showed DBD plasma actuator with burst frequency of 6 provided better control authority in comparison with the burst frequency of 1.
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Fluids engineering conference ..., 2013 "G1005-01"-"G1005-02", Nov 9, 2013Flow and acoustic fields of a transitional supersonic free jet with the moderate Reynolds number are investigated. Compressible Navier-Stokes equations are solved by a high-order compact scheme, and the effects of inflow shear layer characteristics are investigated. The Mach and Reynolds numbers are set to 2.1 and 70,000, respectively. Five different jets with different shear layer thicknesses without disturbances, and the effects of the shear layer thickness and the disturbance are discussed. With decreasing the shear layer thickness or adding the disturbance, the transition position and the turbulence growth rate after the transition are significantly affected, and the turbulent fluctuation along the shear layer and the intensity of resulting Mach waves becomes smaller.
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The Computational Mechanics Conference, 2013(26) "1909-1"-"1909-3", Nov 2, 2013
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Jets, wakes and separated flows : proceedings of International Conference on Jets, Wakes and Separated Flows, ICJWSF, 2013(4) "1137-1"-"1137-6", Sep 16, 2013Large-eddy simulations of a separated flow over NACA0006, NACA0012 and NACA0015 airfoils, which are controlled by a DBD plasma actuator, are conducted to investigate the effect of an airfoil configuration on separation control. Reynolds number is 63,000 for all cases. In these simulations, the position and operation conditions of a DBD plasma actuator are varied as the simulation parameters. The most effective position for separation suppression is near the separation point for all airfoils. The burst frequency with 6 is more effective than 1 to increase the lift-drag ratio in present conditions. The effect of separation control becomes smaller for the cases with larger reverse flow region, and the development of this region significantly influence on the control. Strouhal number based on the momentum thickness is almost the same value in each airfoil case. These values of the burst frequency 6 cases are similar to effective Strouhal number suggested in the past study.
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Jets, wakes and separated flows : proceedings of International Conference on Jets, Wakes and Separated Flows, ICJWSF, 2013(4) "1049-1"-"1049-5", Sep 16, 2013In this study, flow and acoustic fields of a transitional supersonic free jet are investigated. Compressible Navier-Stokes equations are solved by a high-order compact scheme for investigating the effects of inflow shear layer characteristics. The Mach and Reynolds numbers are set to 2.1 and 70,000, respectively. Three different jets with different shear layer thickness are analysed, and the shear layer thickness effects are discussed. With increasing the shear layer, the turbulent fluctuation along the shear layer becomes larger and resulting Mach wave radiation becomes stronger.
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Mechanical Engineering Congress, Japan, 2013 "W121002-1"-"W121002-5", Sep 8, 2013In this study, multiobjective design exploration for a rocket launch site is conducted using evolutionary computation with large eddy simulation to understand the acoustic characteristics associated with various launch sites and find design information such as trade-off relation among design objectives. The launch site is described by curved surface. The flat plate inclined with 45 degree is considered as the reference configuration. The objective functions of multiobjective aero-acoustic design optimization are, 1) minimization of averaged sound pressure level near the payload fairing, 2) minimization of maximum pressure on the curved surface of the rocket launch site, and 3) minimization of the change of the curved surface from the reference configuration. The total number of evaluation in multiobjective evolutionary computation is 2500. The analysis of non-dominated solutions clearly show that there are various trade-off relations and correlations among the objective functions.
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Mechanical Engineering Congress, Japan, 2013 "S052034-1"-"S052034-5", Sep 8, 2013To understand the effects of working parameters of the DBD plasma actuator, investigation with a Multi-Objective Design Exploration(MODE) framework is performed. Experiments with a NACA 0015 airfoil fixed to the stall angle of 12 degrees are conducted at Reynolds number of 63,000. The optimization objectives are to maximize the lift coefficient C_l and minimize the power consumption P. The design variables consist of input power parameters. Despite the small population size, an approximate Pareto-optimal front is found. In the objective function space, a region where there exists a linear relationship between C_l and P is found. After a threshold value, the value of C_l seems to saturate. This paper concentrates on this linear region of the objective function space. We use numerical simulation results with similar parameters to several Pareto-optimal experiment cases to compliment our discussion.
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日本機械学会年次大会講演論文集(CD-ROM), 2013 ROMBUNNO.S052043, Sep 7, 2013
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日本機械学会流体工学部門講演会講演論文集(CD-ROM), 91st ROMBUNNO.G0405, 2013
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The Proceedings of Mechanical Engineering Congress, Japan, 2013 _S052036-1-_S052036-5, 2013Large-eddy simulations of the separated flow over NACA0006, NACA0012 and NACA0015 airfoils, which are controlled by a DBD plasma actuator, are conducted to investigate the effect of airfoil configuration on separation control. In these simulations, position and operation conditions of a DBD plasma actuator, such as the burst frequency, the degree of induced flow, are varied as simulation parameters. It is clarified that the control effects are different from each airfoil even if same numerical parameters are used. Effective position of actuator is near separation point to suppress the separation for all airfoils. The effects of separation control become smaller for cases with larger separation regions, and the separation development significantly influence on the control.
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Fluids engineering conference ..., 2012 525-526, Nov 16, 2012Induced flow fields by a dielectric barrier discharge (DBD) plasma actuator installed on a flat plate in quiescent flow are analyzed numerically. The produced airflow resulting from a simple sine waveform and burst modulations is discussed. The correlation between the operating mode of DBD plasma actuator and the resulting flow: fields generated in temporal and average domains is presented. The generated flow resulting from a simple sine waveform is quasi-steady and fluctuates with base frequency of actuation. On the other hand, the induced flow structure by the burst modulations is unsteady and shows the dependency of actuation modes in terms of instantaneous sense
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The Computational Mechanics Conference, 2012(25) 16-18, Oct 6, 2012One of the techniques for the discretization of time metrics and the Jacobian is to rewrite their analytical expression into conservative forms. In this research, we give the geometrical interpretation for discretized conservative metrics evaluated by any higher-order finite difference method.
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Mechanical Engineering Congress, Japan, 2011 "S055032-1"-"S055032-2", Sep 11, 2011The dielectric barrier electric discharge plasma actuator is expected as a new technology which can make the design of an aerofoil etc. unnecessary. The boundary layer control might be able to be performed by induced velocity in the boundary layer as an effect of the dielectric substance barrier electrical discharge plasma actuator. Moreover, it also turns out that the control effectiveness increases by repeating ON and OFF of the applied voltage, which is called burst. In this study, separation control on an airfoil by a plasma actuator was performed, and its control effectiveness was evaluated. This paper showed the effective mechanism of burst control by PIV.
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2009(19) 542-547, Oct 28, 2009Aerodynamic characteristics of reusable observation vehicle are computationally investigated under subsonic and supersonic flows using the RANS (Reynolds-averaged Navier-Stokes) simulations. The initial investigation for the concept design is done with the light optimization using the light CFD. The results show that the simulations using coarse grid estimate the axial force coefficient and the lift to drag ratio accurately except some cases. The results indicate the correlation between the supersonic lift to drag ratio and the axial force coefficient. The results show the correlation between the y-coordinate of the design variable and the volume. The required knowledge for the concept design in the near future is obtained.
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Proceedings of the conference on computational engineering and science, 13(1) 431-434, May 19, 2008
Books and Other Publications
31-
Cambridge University Press, Apr, 2015
Presentations
1066-
AJK FED2023(ASME-JSME-KSME Joint Fluids Engineering Conference), Jul 9, 2023
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AJK FED2023(ASME-JSME-KSME Joint Fluids Engineering Conference), Jul 9, 2023
Professional Memberships
11Works
20Research Projects
28-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2018 - Mar, 2021
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Nov, 2017 - Mar, 2019
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萌芽的課題研究, ポスト「京」で重点的に取り組むべき社会的・科学的課題に関するアプリケーション開発・研究開発, Aug, 2016 - Mar, 2019
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科学研究費補助金基盤A, 日本学術振興会, Apr, 2015 - Mar, 2018
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2012 - Mar, 2015