HUGE DIRECT NUMERICAL SIMULATION OF TURBULENT COMBUSTION - TOWARD PERFECT SIMULATION OF IC ENGINE -

Tanahashi, Mamoru,Seo, Takehiko,Sato, Makoto,Tsunemi, Akihiko,Miyauchi, Toshio Korea Society of Computational Fluids Engineering 2008 한국전산유체공학회지 Vol.13 No.4

Current state and perspective of DNS of turbulence and turbulent combustion are discussed with feature trend of the fastest supercomputer in the world. Based on the perspective of DNS of turbulent combustion, possibility of perfect simulations of IC engine is shown. In 2020, the perfect simulation will be realized with 30 billion grid points by 1EXAFlops supercomputer, which requires 4 months CPU time. The CPU time will be reduced to about 4 days if several developments were achieved in the current fundamental researches. To shorten CPU time required for DNS of turbulent combustion, two numerical methods are introduced to full-explicit full-compressible DNS code. One is compact finite difference filter to reduce spatial resolution requirements and numerical oscillations in small scales, and another is well-known point-implicit scheme to avoid quite small time integration of the order of nanosecond for fully explicit DNS. Availability and accuracy of these numerical methods have been confirmed carefully for auto-ignition, planar laminar flame and turbulent premixed flames. To realize DNS of IC engine with realistic kinetic mechanism, several DNS of elemental combustion process in IC engines has been conducted.

A NOTE ON ∗-PARANORMAL OPERATORS AND RELATED CLASSES OF OPERATORS

Tanahashi, Kotoro,Uchiyama, Atsushi Korean Mathematical Society 2014 대한수학회보 Vol.51 No.2

We shall show that the Riesz idempotent $E_{\lambda}$ of every *-paranormal operator T on a complex Hilbert space H with respect to each isolated point ${\lambda}$ of its spectrum ${\sigma}(T)$ is self-adjoint and satisfies $E_{\lambda}\mathcal{H}=ker(T-{\lambda})= ker(T-{\lambda})^*$. Moreover, Weyl's theorem holds for *-paranormal operators and more general for operators T satisfying the norm condition $||Tx||^n{\leq}||T^nx||\,||x||^{n-1}$ for all $x{\in}\mathcal{H}$. Finally, for this more general class of operators we find a sufficient condition such that $E_{\lambda}\mathcal{H}=ker(T-{\lambda})= ker(T-{\lambda})^*$ holds.

A NOTE ON *-PARANORMAL OPERATORS AND RELATED CLASSES OF OPERATORS

Kotaro Tanahashi,Atsushi Uchiyama 대한수학회 2014 대한수학회보 Vol.51 No.2

We shall show that the Riesz idempotent E of every ∗- paranormal operator T on a complex Hilbert space H with respect to each isolated point of its spectrum (T) is self-adjoint and satisfies EH = ker(T − ) = ker(T − )∗. Moreover, Weyl’s theorem holds for ∗-paranormal operators and more general for operators T satisfying the norm condition ∥Tx∥n ≤ ∥Tnx∥kx∥n−1 for all x ∈ H. Finally, for this more general class of operators we find a sufficient condition such that EH = ker(T − ) = ker(T − )∗ holds. We shall show that the Riesz idempotent E of every ∗- paranormal operator T on a complex Hilbert space H with respect to each isolated point of its spectrum (T) is self-adjoint and satisfies EH = ker(T − ) = ker(T − )∗. Moreover, Weyl’s theorem holds for ∗-paranormal operators and more general for operators T satisfying the norm condition ∥Tx∥n ≤ ∥Tnx∥∥x∥n−1 for all x ∈ H. Finally, for this more general class of operators we find a sufficient condition such that EH = ker(T − ) = ker(T − )∗ holds.

Huge Direct Numerical Simulation of Turbulent Combustion

Mamoru Tanahashi 한국전산유체공학회 2008 한국전산유체공학회 학술대회논문집 Vol.2008 No.3

Huge Direct Numerical Simulation of Turbulent Combustion

Mamoru Tanahashi 한국전산유체공학회 2008 한국전산유체공학회 학술대회논문집 Vol.2008 No.-

Current state and perspective of DNS of turbulence and turbulent combustion are discussed with feature trend of the fastest supercomputer in the world. Based on the perspective of DNS of turbulent combustion, possibility of perfect simulations of IC engine is shown. In 2020, the perfect simulation will be realized with 30 billion grid points by IEXAFlops supercomputer, which requires 4 months CPU time. The CPU time will be reduced to about 4 days if several developments were achieved in the current fundamental researches. To shorten CPU time required for DNS of turbulent combustion, two numerical methods are introduced to full-explicit full-compressible DNS code. One is compact finite difference filter to reduce spatial resolution requirements and numerical oscillations in small scales, and another is well-known point-implicit scheme to avoid quite small time integration of the order of nanosecond for fully explicit DNS. Availability and accuracy of these numerical methods have been confirmed carefully for auto-ignition, planar laminar flame and turbulent premixed flames. To realize DNS of IC engine with realistic kinetic mechanism, several DNS of elemental combustion process in IC engines has been conducted.

DNS of Turbulent Combustion toward Perfect Simulation of IC Engine

Mamoru Tanahashi 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.39

Current state and perspective of DNS of turbulence and turbulent combustion are discussed with feature trend of the fastest supercomputer in the world. Based on the perspective of DNS of turbulent combustion, possibility of perfect simulations of IC engine is shown. In 2020, the perfect simulation will be realized with 30 billion grid points by 1 EXAFlops supercomputer, which requires 4 months CPU time. The CPU time will be reduced to about 4 days if several developments were achieved in the current fundamental researches. To shorten CPU time required for DNS of turbulent combustion, two numerical methods are introduced to full-explicit full-compressible DNS code. One is compact finite difference filter to reduce spatial resolution requirements and numerical oscillations in small scales, and another is well-known point-implicit scheme to avoid quite small time integration of the order of nanosecond for fully explicit DNS. Availability and accuracy of these numerical methods have been confirmed carefully for auto-ignition, planar laminar flame and turbulent premixed flames. To realize DNS of IC engine with realistic kinetic mechanism, several DNS of elemental combustion process in IC engines has been conducted.

DNS and Combined Laser Diagnostics of Turbulent Premixed Flame

Mamoru Tanahashi,Masayasu Shimura,Toshio Miyauchi 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.38

With the developments of computer technologies, three-dimensional direct numerical simulations (DNS) of turbulent combustion have been realized with a detailed or reduced kinetic mechanism. The 3D DNS gives detailed information about turbulent flames, while there are few experimental techniques which have high accuracy enough to compare with DNS. In this paper, after showing summary of recent DNS of turbulent premixed flames, newly-developed laser diagnostics are presented. Simultaneous CH-OH planar laser induced fluorescence (PLIF) and stereoscopic particle image velocimetry (PIV) are used to investigate the local flame structure of the turbulent premixed flames. From CH-OH PLIF and PIV measurements, flame fronts are identified, and the curvature of the flame front and the tangential strain rate at the flame front are evaluated. The experimental results are compared with 3D DNS of hydrogen-air and methane-air turbulent premixed flames. The flame displacement speeds in turbulent premixed flames have been measured directly by the CH double-pulsed PLIF. Since the time interval of the successive CH PLIF can be selected arbitrarily, both of the large scale dynamics and local displacement of the flame front can be obtained. As an application of laser diagnostics for development of high-efficient and low-emission combustors, reconstruction of 3D flame structure is shown by using multiple-plane OH PLIF.

Effects of Manual Acupuncture at GB34 on Carbon tetrachloride-induced Acute Liver Injury in Rats

Nobuyuki Tanahashi,Juri Shikami,Misao Yoneda,Torao Ishida 사단법인약침학회 2011 Journal of Acupuncture & Meridian Studies Vol.4 No.4

Manual acupuncture at Yanglingquan (GB34) is reported to have a beneficial effect on chronic liver damage. We, therefore, studied the effect of manual acupuncture at GB34 on acute liver damage. Rats were administered carbon tetrachloride (CCl₄) or olive oil, and direct manual acupuncture was subsequently performed at GB34 or at a sham point (a nonacupoint). In rats administered with CCl₄, the serum levels of aspartate aminotransferase and alanine aminotransferase, the total cholesterol concentration, and the levels of hepatic thiobarbituric-acid-reactive substances were suppressed by acupuncture at GB34 when compared with acupuncture at the sham point. By contrast, there was little histological difference in the liver between acupuncture at GB34 and that at the sham point in rats administered with CCl₄. These results suggest that manual acupuncture at GB34 tends to improve acute liver damage but is not sufficient by itself to completely resolve the hepatic injury.

HUGE DIRECT NUMERICAL SIMULATION OF TURBULENT COMBUSTION

Mamoru Tanahashi,Takehiko Seo,Makoto Sato,Akihiko Tsunemi,Toshio Miyauchi 한국전산유체공학회 2008 한국전산유체공학회지 Vol.13 No.4

Current state and perspective of DNS of turbulence and turbulent combustion are discussed with feature trend of the fastest supercomputer in the world. Based on the perspective of DNS of turbulent combustion, possibility of perfect simulations of IC engine is shown. In 2020, the perfect simulation will be realized with 30 billion grid points by 1 EXAFlops supercomputer, which requires 4 months CPU time. The CPU time will be reduced to about 4 days if several developments were achieved in the current fundamental researches. To shorten CPU time required for DNS of turbulent combustion, two numerical methods are introduced to full-explicit full-compressible DNS code. One is compact finite difference filter to reduce spatial resolution requirements and numerical oscillations in small scales, and another is well-known point-implicit scheme to avoid quite small time integration of the order of nanosecond for fully explicit DNS. A vailability and accuracy of these numerical methods have been confirmed carefully for auto-ignition, planar laminar flame and turbulent premixed flames. To realize DNS of IC engine with realistic kinetic mechanism, several DNS of elemental combustion process in IC engines has been conducted.

A SYSTEMIC OUTLOOK OF CREATIVE TOURISM

T. Keisei Tanahashi 세계문화관광학회 2009 Conference Proceedings Vol.10 No.0

Creative tourism distinguishes itself from cultural tourism in two ways. One is its objective, which is to cater for individuals’ cultural interest, and the other is the active involvement of tourists in preparation as well as cultural activities and events for tourism. Thus, development of creative tourism much depends on the initiatives and entrepre neurship of local tourism operators, instead of travel agencies who promote mass tourism. Communal involvement in creative tourism helps in preserving its valuable cultural assets and traditions, and also enhances sustainable economic development, even in communities that lack resources or potentials for industrial development. However, such communal efforts cannot succeed without integration into the national design and system for tourism development. Three developmental issues are critical for its success. They are: (a) communication between individual tourists and destination localities, (b) societal espousal of cross-cultural or inter-cultural education and experience, and (c) societal fabric for promotion of hospitality. This paper elucidates some prospects and pitfalls for viable systemic development of creative tourism.