Japanese/English

Dept. of Mechanical & Aerospace Engineering, School of Engineering, Tohoku University

Fluid Mechanics Lab. (Shigeta Group)

Plasma Fluid Mechanics etc.

Research works

We study high-energy fluid processes such as material fabrication/manufacturing and harmful substance decomposition using plasma over 10,000 K. Because those processes involve complex physical interactions as well as very hot and very bright, they are hardly investigated by conventional methods. We develop innovative methods to "see, observe, diagnose" those invisible phenomena with the purposes of mechanism elucidation and new process creation.


Click the movie to play.

Development of flow simulation method
for high enthalpy plasma - nonionized gas coexisting systems



Simulation of high-enthaply plasma flow such as thermal plasma flow is generally difficult. The entire flow field, in which the plasma at a high temperature and a cold gas at room temperature co-exist, must be treated simultaneously. Widely varied temperatures of 300-12,000 K cause large variations of the transport properties and the density. Meanwhile, the Mach numbers are very small in and around the plasma. When a numerical method for a compressible flow simulation is used for such a flow field, the computation takes an extremely long time to obtain a numerical solution for a practical time scale. Therefore, a thermal plasma is treated as an incompressible flow with the density as a temperatur-edependent variable. This condition, which is severe for numerical flow simulations, usually destabilizes the computation (= the computation easily breaks down). That is why thermal plasma simulations have often used differencing schemes which suppress numerical instability effectively. However, those schemes also suppress the actual physical instability simultaneously. In consequence, the numerical result does not simulate any realistic flow with vortices. On the other hand, schemes suitable for vortex capturing often cause destabilization of computations. Although these two aspects mutually conflict, a new method combining those schemes and algorithm has been long-awaited to simulate vortex motions in and around high-enthalpy plasma flows. A innovative simulation method that acheives both capturing of physical insitability (vortex motions) and numerically-stable long-time computation at the same time was developed successfully.
For example, an experiment visualized that a thermal plasma jet entrained surrounding cold gas by Kelvin-Helmholtz instability, induced many vortices even far from the plasma core, and transited to a turbulent state with vortex breakup about 30 years ago. Nevertheless, such a flow had never been simulated because of the numerically severe conditions. Overcoming the difficulties, the present effort broke through that problem and obtaiend a successful result.

Special thanks to Cyberscience Center, Tohoku University

For more information, see ...
  • Time-Dependent 3-D Simulation of an Argon RF Inductively Coupled Thermal Plasma,
     Plasma Sources Science and Technology, Vol. 21, No. 5, (October, 2012), pp. 055029 (14 pages).
     Masaya Shigeta
  • Three-dimensional flow dynamics of an argon RF plasma with DC jet assistance: a numerical study,
     Journal of Physics D: Applied Physics, Vol. 46, No. 1, (January, 2013) 015401 (12 pages).
     Masaya Shigeta
  • Turbulence modelling of thermal plasma flows,
     Journal of Physics D: Applied Physics, Vol. 49, No. 49, (November, 2016), pp. 493001 (18 pages).
     Masaya Shigeta
  • Numerical Study of Axial Magnetic Effects on a Turbulent Thermal Plasma Jet for Nanopowder Production Using 3D Time-Dependent Simulation,
     Journal of Flow Control, Measurement & Visualization, Vol. 6, (April, 2018), pp. 107-123.
     Masaya Shigeta
  • Modeling and Simulation of a Turbulent-like Thermal Plasma Jet for Nanopowder Production,
     IEEJ Transactions on Electrical and Electronic Engineering, Vol. 14, (January, 2019), pp. 16-28.
     Masaya Shigeta
  • Simulating Turbulent Thermal Plasma Flows for Nanopowder Fabrication,
     Plasma Chemistry and Plasma Processing, Vol. 40, Issue 3, (May, 2020), pp. 775-794.
     Masaya Shigeta

  • Click the movie to play.

    Particle method simulation of molten metal flow & heat transfer
    in welding processes



    The details will be provided soon.

    See also Web Manga (Catoon). FREE ACCESS
  • What is usage of welding process simulation?
     The Japan Welding Engineering Society WE-COM Magazine "Dr. Naniwa's Welding Gatten! R". [in Japanese]
     Story: SHIGETA Masaya, Art: KARANO Tatsuko

    Special thanks to Tanaka Lab. JWRI, Osaka University


    For more information, see ...
  • Numerical Simulation of a Weld Pool Formation in a TIG Welding Using an Incompressible SPH Method,
     quarterly Journal of the Japan Welding Society, Vol. 32, No. 4, (December, 2014), pp. 213-222. [in Japanese]
     Masumi ITO, Seiichiro IZAWA, Yu FUKUNISHI, Masaya Shigeta
  • Numerical Simulation of Joining Process in a TIG Welding System Using Incompressible SPH Method,
     Quarterly Journal of the Japan Welding Society, Vol. 33, No.2, (May, 2015), pp. 32s-38s.
     Masumi Ito, Yu Nishio, Seiichiro Izawa, Yu Fukunishi, and Masaya Shigeta
  • Numerical Simulation of Droplet Transfer with TiO2 Flux Column During Flux Cored Arc Welding by 3D Smoothed Particle Hydrodynamics Method,
     Quarterly Journal of the Japan Welding Society, Vol. 38, No. 2, (May, 2020), pp. 84s-88s.
     Ryo UENO, Hisaya KOMEN, Masaya Shigeta, Manabu TANAKA


  • Click the movie to play.

    Experimental visualization measurements
    for high-temperature manufacturing processes



    The details will be provided soon.

    Special thanks to Tanaka Lab. JWRI, Osaka University

    For more information, see ...
  • Investigation of the bilayer region of metal vapor in a helium tungsten inert gas arc plasma on stainless steel by imaging spectroscopy,
     Journal of Physics D: Applied Physics, Vol. 52, No. 35, (August, 2019), pp. 354003 (9 pages).
     Keigo Tanaka, Masaya Shigeta, Manabu Tanaka, Anthony B. Murphy
  • Visualization of electromagnetic-thermal-fluid phenomena in arc welding,
     Japanese Journal of Applied Physics, Vol. 59, (November, 2019), pp. SA0805 (12 pages).
     Masaya Shigeta, Manabu Tanaka
  • Imaging Spectroscopy for Transient Transport of Chromium Vapor During Helium TIG Welding,
     Quarterly Journal of the Japan Welding Society, Vol. 38, No. 2, (April, 2020), pp. 21s-24s.
     Keigo TANAKA, Masaya Shigeta, Manabu TANAKA, Anthony B. MURPHY
  • Investigation of transient metal vapour transport processes in helium arc welding by imaging spectroscopy,
     Journal of Physics D: Applied Physics, Vol. 53, No. 42, (July, 2020), pp. 425202 (8 pages).
     Keigo Tanaka, Masaya Shigeta, Manabu Tanaka, Anthony B. Murphy

  • Click the movie to play.

    Mathematical formulation & algorithm development
    for nanopowder formation in plasma flows



    Plasma flow is expected as promising fluid that achieves mass-fabrication of nanometer-scale ultrafine particles (nanopowder). However, the physical phenomena are still poorly understood because it is very difficult to observe and measure directly the high-temperature flow field and nanopowder formation progressing in nano-second to milli-second time scales. Deep understanding of the physics is required to fabricate nanopowder desirable for specific purposes. To overcome that problem, we are addressing the mathematical formulations and developing the numerical algorithms.

    Nanoparticles have been anticipated for application in various field.
  • Environmental: Catalysts, Solar panels, Fuel cells
  • Bio/Medical: DNA detection, Drug delivery, Anti-allergic agents
  • Engineering: VLSI, Heat/oxidation resistant electrodes, Next generation high performance magnets
    Efficient and highly-accurate mass-fabrication of nanopowder leads to rapid progress of those fields; in consequence, it will bring many innovations.

    The final objective of this study is to develop a virtual experiment system in computer. This system will analyze the physical phenomena in detail, repeat the virtual experiments at low costs, and overcome the big problem of “high-cost equipment and running” in experimental studies. More innovative control methods of nanopowder synthesis and production of nanopowder with new characteristics will be expected as well.

    Special thanks to Cyberscience Center, Tohoku University

    For more information, see ...
  • Growth model of binary alloy nanopowders for thermal plasma synthesis,
     Journal of Applied Physics, Vol. 108, Issue 4, (August, 2010), pp. 043306 (15 pages).
     Masaya Shigeta and Takayuki Watanabe
  • Simple equations to describe aerosol growth,
     Modelling and Simulation in Materials Science and Engineering, Vol. 20, No. 4, (May, 2012), pp. 045017 (11 pages).
     Valerian A. Nemchinsky and Masaya Shigeta
  • Effect of precursor fraction on silicide nanopowder growth under thermal plasma conditions: a computational study,
     Powder Technology, Vol. 288, (January, 2016), pp. 191-201.
     Masaya Shigeta, Takayuki Watanabe
  • Effect of Saturation Pressure Difference on Metal-Silicide Nanopowder Formation in Thermal Plasma Fabrication,
     Nanomaterials, Vol. 6, (March, 2016), pp. 43 (10 pages).
     Masaya Shigeta, Takayuki Watanabe
  • Numerical Study of Axial Magnetic Effects on a Turbulent Thermal Plasma Jet for Nanopowder Production Using 3D Time-Dependent Simulation,
     Journal of Flow Control, Measurement & Visualization, Vol. 6, (April, 2018), pp. 107-123.
     Masaya Shigeta
  • Modeling and Simulation of a Turbulent-like Thermal Plasma Jet for Nanopowder Production,
     IEEJ Transactions on Electrical and Electronic Engineering, Vol. 14, (January, 2019), pp. 16-28.
     Masaya Shigeta
  • Numerical analysis of correlation between arc plasma fluctuation and nanoparticle growth-transport under atmospheric pressure,
     Nanomaterials, Vol. 9, No. 12, (December, 2019), pp. 1736 (13 pages).
     Masaya Shigeta, Manabu Tanaka, Emanuele Ghedini
  • Simulating Turbulent Thermal Plasma Flows for Nanopowder Fabrication,
     Plasma Chemistry and Plasma Processing, Vol. 40, Issue 3, (May, 2020), pp. 775-794.
     Masaya Shigeta
  • Anisotropic Nd-Fe ultrafine particles with stable and metastable phases prepared by induction thermal plasma,
     Journal of Alloys and Compounds, Vol. 873, No. 25, (August, 2021) pp. 159724 (9 pages).
     Y. Hirayama, M. Shigeta, Z. Liu, N. Yodoshi, A. Hosokawa, K. Takagi
  • Anisotropic Sm-Co nanopowder prepared by induction thermal plasma,
     Journal of Alloys and Compounds, Vol. 882, No. 15, (November, 2021), ppl. 160633 (10 pages).
     Kwangjae Park, Yusuke Hirayama, Masaya Shigeta, Zheng Liu, Makoto Kobashi, Kenta Takagi

  • The following topics are described in Shigeta's personal website.
  • Three-dimensional flow dynamics of a DC-RF hybrid thermal plasma
  • Fundamental problem in numerical simulation of thermal plasmas
  • Simple equations to describe aerosol growth
  • Collective growth of silicide nanoparticles (nanopowder) in thermal plasma synthesis
  • Radio-frequency inductively coupled thermal plasma flow & nanoparticle formation with counterflow cooling
  • Arc plasma dynamics in a TIG welding condition
  • Dynamics of two non-neutral plasma rings in a uniform magnetic field