The Experts below are selected from a list of 122220 Experts worldwide ranked by ideXlab platform
Yutaka Tsuji - One of the best experts on this subject based on the ideXlab platform.
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Direct numerical simulation of Particle dispersion in a turbulent jet considering inter-Particle Collisions
International Journal of Multiphase Flow, 2008Co-Authors: Jie Yan, Yutaka Tsuji, Kun Luo, Jianren Fan, Kefa CenAbstract:Abstract To investigate the behaviour of inter-Particle collision and its effects on Particle dispersion, direct numerical simulation of a three-dimensional two-phase turbulent jet was conducted. The finite volume method and the fractional-step projection algorithm were used to solve the governing equations of the gas phase fluid and the Lagrangian method was applied to trace the Particles. The deterministic hard-sphere model was used to describe the inter-Particle collision. In order to allow an analysis of inter-Particle Collisions independent of the effect of Particles on the flow, two-way coupling was neglected. The inter-Particle collision occurs frequently in the local regions with higher Particle concentration of the flow field. Under the influence of the local accumulation and the turbulent transport effects, the variation of the average inter-Particle collision number with the Stokes number takes on a complex non-linear relationship. The Particle distribution is more uniform as a result of inter-Particle Collisions, and the lateral and the spanwise dispersion of the Particles considering inter-Particle collision also increase. Furthermore, for the case of Particles with the Rosin–Rammler distribution (the medial Particle size is set d 50 = 36.7 μm), the collision number is significantly larger than that of the Particles at the Stokes number of 10, and their effects on calculated results are also more significant.
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large eddy simulation of turbulent gas Particle flow in a vertical channel effect of considering inter Particle Collisions
Journal of Fluid Mechanics, 2001Co-Authors: Yasufumi Yamamoto, M Potthoff, Toshitsugu Tanaka, Takeo Kajishima, Yutaka TsujiAbstract:The interaction between a turbulent gas flow and Particle motion was investigated by numerical simulations of gas–Particle turbulent downward flow in a vertical channel. In particular the effect of inter-Particle collision on the two-phase flow field was investigated. The gas flow field was obtained by large-eddy simulation (LES). Particles were treated by a Lagrangian method, with inter-Particle Collisions calculated by a deterministic method. The spatial resolution for LES of gas–solid two-phase turbulent flow was examined and relations between grid resolution and Stokes number are presented. Profiles of Particle mean velocity, Particle wall-normal fluctuation velocity and number density are flattened as a result of inter-Particle Collisions and these results are in good agreement with experimental measurements. Calculated turbulence attenuation by Particles agrees well with experimental measurements for small Stokes numbers, but not for large Stokes number Particle. The shape and scale of Particle concentrations calculated considering inter-Particle collision are in good agreement with experimental observations.
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Large-eddy simulation of turbulent gas–Particle flow in a vertical channel: effect of considering inter-Particle Collisions
Journal of Fluid Mechanics, 2001Co-Authors: Yasufumi Yamamoto, M Potthoff, Toshitsugu Tanaka, Takeo Kajishima, Yutaka TsujiAbstract:The interaction between a turbulent gas flow and Particle motion was investigated by numerical simulations of gas–Particle turbulent downward flow in a vertical channel. In particular the effect of inter-Particle collision on the two-phase flow field was investigated. The gas flow field was obtained by large-eddy simulation (LES). Particles were treated by a Lagrangian method, with inter-Particle Collisions calculated by a deterministic method. The spatial resolution for LES of gas–solid two-phase turbulent flow was examined and relations between grid resolution and Stokes number are presented. Profiles of Particle mean velocity, Particle wall-normal fluctuation velocity and number density are flattened as a result of inter-Particle Collisions and these results are in good agreement with experimental measurements. Calculated turbulence attenuation by Particles agrees well with experimental measurements for small Stokes numbers, but not for large Stokes number Particle. The shape and scale of Particle concentrations calculated considering inter-Particle collision are in good agreement with experimental observations.
Fengwei Chen - One of the best experts on this subject based on the ideXlab platform.
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Particle Collisions on stringy black hole background
Journal of High Energy Physics, 2010Co-Authors: Shaowen Wei, Yuxiao Liu, Fengwei ChenAbstract:The collision of two Particles in the background of a Sen black hole is studied. With the equations of motion of the Particles, the center-of-mass energy is investigated when the collision takes place at the horizon of a Sen black hole. For an extremal Sen black hole, we find that the center-of-mass energy will be arbitrarily high with two conditions: (1) spin a 6 0 and (2) one of the colliding Particles has the critical angular momentum lc = 2. For a nonextremal Sen black hole, we show that, in order to obtain an unlimited center- of-mass energy, one of the colliding Particles should have the critical angular momentum l ' = 2r+/a (r+ is the radius of the outer horizon for a nonextremal black hole). However, a Particle with the angular momentum l = lcould not approach the black hole from outside of the horizon through free fall, which implies that the collision with arbitrarily high center- of-mass energy could not take place. Thus, there is an upper bound of the center-of-mass energy for the nonextremal black hole. We also obtain the maximal center-of-mass energy for a near-extremal black hole and the result implies that the Planck-scale energy is hard to be approached. Furthermore, we also consider the back-reaction effects. The result shows that, neglecting the gravitational radiation, it has a weak effect on the center-of- mass energy. However, we argue that the maximum allowed center-of-mass energy will be greatly reduced to below the Planck-scale when the gravitational radiation is included.
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Particle Collisions on stringy black hole background
arXiv: High Energy Physics - Theory, 2010Co-Authors: Shaowen Wei, Yuxiao Liu, Fengwei ChenAbstract:The collision of two Particles in the background of a Sen black hole is studied. With the equations of motion of the Particles, the center-of-mass energy is investigated when the collision takes place at the horizon of a Sen black hole. For an extremal Sen black hole, we find that the center-of-mass energy will be arbitrarily high with two conditions: (1) spin $a\neq 0$ and (2) one of the colliding Particles has the critical angular momentum $l_{\text{c}}=2$. For a nonextremal Sen black hole, we show that, in order to obtain an unlimited center-of-mass energy, one of the colliding Particles should have the critical angular momentum $l'_{\text{c}}=2 r_{+}/a$ ($r_{+}$ is the radius of the outer horizon for a nonextremal black hole). However, a Particle with the angular momentum $l=l'_{\text{c}}$ could not approach the black hole from outside of the horizon through free fall, which implies that the collision with arbitrarily high center-of-mass energy could not take place. Thus, there is an upper bound of the center-of-mass energy for the nonextremal black hole. We also obtain the maximal center-of-mass energy for a near-extremal black hole and the result implies that the Planck-scale energy is hard to be approached. Furthermore, we also consider the back-reaction effects. The result shows that, neglecting the gravitational radiation, it has a weak effect on the center-of-mass energy. However, we argue that the maximum allowed center-of-mass energy will be greatly reduced to below the Planck-scale when the gravitational radiation is included.
Yasufumi Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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large eddy simulation of turbulent gas Particle flow in a vertical channel effect of considering inter Particle Collisions
Journal of Fluid Mechanics, 2001Co-Authors: Yasufumi Yamamoto, M Potthoff, Toshitsugu Tanaka, Takeo Kajishima, Yutaka TsujiAbstract:The interaction between a turbulent gas flow and Particle motion was investigated by numerical simulations of gas–Particle turbulent downward flow in a vertical channel. In particular the effect of inter-Particle collision on the two-phase flow field was investigated. The gas flow field was obtained by large-eddy simulation (LES). Particles were treated by a Lagrangian method, with inter-Particle Collisions calculated by a deterministic method. The spatial resolution for LES of gas–solid two-phase turbulent flow was examined and relations between grid resolution and Stokes number are presented. Profiles of Particle mean velocity, Particle wall-normal fluctuation velocity and number density are flattened as a result of inter-Particle Collisions and these results are in good agreement with experimental measurements. Calculated turbulence attenuation by Particles agrees well with experimental measurements for small Stokes numbers, but not for large Stokes number Particle. The shape and scale of Particle concentrations calculated considering inter-Particle collision are in good agreement with experimental observations.
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Large-eddy simulation of turbulent gas–Particle flow in a vertical channel: effect of considering inter-Particle Collisions
Journal of Fluid Mechanics, 2001Co-Authors: Yasufumi Yamamoto, M Potthoff, Toshitsugu Tanaka, Takeo Kajishima, Yutaka TsujiAbstract:The interaction between a turbulent gas flow and Particle motion was investigated by numerical simulations of gas–Particle turbulent downward flow in a vertical channel. In particular the effect of inter-Particle collision on the two-phase flow field was investigated. The gas flow field was obtained by large-eddy simulation (LES). Particles were treated by a Lagrangian method, with inter-Particle Collisions calculated by a deterministic method. The spatial resolution for LES of gas–solid two-phase turbulent flow was examined and relations between grid resolution and Stokes number are presented. Profiles of Particle mean velocity, Particle wall-normal fluctuation velocity and number density are flattened as a result of inter-Particle Collisions and these results are in good agreement with experimental measurements. Calculated turbulence attenuation by Particles agrees well with experimental measurements for small Stokes numbers, but not for large Stokes number Particle. The shape and scale of Particle concentrations calculated considering inter-Particle collision are in good agreement with experimental observations.
Pengming Zhang - One of the best experts on this subject based on the ideXlab platform.
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kinematic surprises in twisted Particle Collisions
Physical Review D, 2020Co-Authors: I P Ivanov, Nikolai Korchagin, Alexandr Pimikov, Pengming ZhangAbstract:``Twisted Particles'' refer to non-plane-wave states of photons, electrons, hadrons, or any other Particles which carry nonzero, adjustable orbital angular momentum with respect to their average propagation direction. Twisted photons and electrons have already been experimentally demonstrated, and one can expect creation of twisted states of other Particles in the future. Such states can be brought in Collisions, offering a completely new degree of freedom in collider experiments and, especially, a novel tool for hadronic physics. We recently showed that $2\ensuremath{\rightarrow}1$ processes with two twisted Particles such as resonance production in twisted ${e}^{+}{e}^{\ensuremath{-}}$ annihilation give access to observables which are difficult or impossible to probe in the usual plane wave Collisions. In this paper, we discuss in detail surprising kinematic features of this process, focusing on spinless Particle annihilation. They include 1) a new dimension in the final momentum space available in twisted annihilation, 2) interference fringes emerging in the cross section as a function of the total energy, and 3) the built-in mass spectrometric capability of this process, that is, simultaneous production and automatic angular separation of several resonances with different masses in monochromatic twisted Particle annihilation experiment running at fixed energy. All these features cannot be obtained in the usual plane wave collision setting.
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kinematic surprises in twisted Particle Collisions
arXiv: High Energy Physics - Phenomenology, 2019Co-Authors: I P Ivanov, Nikolai Korchagin, Alexandr Pimikov, Pengming ZhangAbstract:"Twisted Particles" refer to non-plane-wave states of photons, electrons, hadrons, or any other Particle which carry non-zero, adjustable orbital angular momentum with respect to their average propagation direction. Twisted photons and electrons have already been experimentally demonstrated, and one can expect creation of twisted states of other Particles in future. Such states can be brought in Collisions, offering a completely new degree of freedom in collider experiments and, especially, a novel tool for hadronic physics. We recently showed that $2 \to 1$ processes with two twisted Particles such as resonance production in twisted $e^+e^-$ annihilation give access to observables which are difficult or impossible to probe in the usual plane-wave Collisions. In this paper, we discuss in detail surprising kinematic features of this process, focusing on spinless Particle annihilation. They include (1) a new dimension in the final momentum space available in twisted annihilation, (2) interference fringes emerging in the cross section as a function of the total energy, and (3) the built-in mass spectrometric capability of this process, that is, simultaneous production and automatic angular separation of several resonances with different masses in monochromatic twisted Particle annihilation experiment running at fixed energy. All these features cannot be obtained in the usual plane wave collision setting.
Alexandr Pimikov - One of the best experts on this subject based on the ideXlab platform.
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kinematic surprises in twisted Particle Collisions
Physical Review D, 2020Co-Authors: I P Ivanov, Nikolai Korchagin, Alexandr Pimikov, Pengming ZhangAbstract:``Twisted Particles'' refer to non-plane-wave states of photons, electrons, hadrons, or any other Particles which carry nonzero, adjustable orbital angular momentum with respect to their average propagation direction. Twisted photons and electrons have already been experimentally demonstrated, and one can expect creation of twisted states of other Particles in the future. Such states can be brought in Collisions, offering a completely new degree of freedom in collider experiments and, especially, a novel tool for hadronic physics. We recently showed that $2\ensuremath{\rightarrow}1$ processes with two twisted Particles such as resonance production in twisted ${e}^{+}{e}^{\ensuremath{-}}$ annihilation give access to observables which are difficult or impossible to probe in the usual plane wave Collisions. In this paper, we discuss in detail surprising kinematic features of this process, focusing on spinless Particle annihilation. They include 1) a new dimension in the final momentum space available in twisted annihilation, 2) interference fringes emerging in the cross section as a function of the total energy, and 3) the built-in mass spectrometric capability of this process, that is, simultaneous production and automatic angular separation of several resonances with different masses in monochromatic twisted Particle annihilation experiment running at fixed energy. All these features cannot be obtained in the usual plane wave collision setting.
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kinematic surprises in twisted Particle Collisions
arXiv: High Energy Physics - Phenomenology, 2019Co-Authors: I P Ivanov, Nikolai Korchagin, Alexandr Pimikov, Pengming ZhangAbstract:"Twisted Particles" refer to non-plane-wave states of photons, electrons, hadrons, or any other Particle which carry non-zero, adjustable orbital angular momentum with respect to their average propagation direction. Twisted photons and electrons have already been experimentally demonstrated, and one can expect creation of twisted states of other Particles in future. Such states can be brought in Collisions, offering a completely new degree of freedom in collider experiments and, especially, a novel tool for hadronic physics. We recently showed that $2 \to 1$ processes with two twisted Particles such as resonance production in twisted $e^+e^-$ annihilation give access to observables which are difficult or impossible to probe in the usual plane-wave Collisions. In this paper, we discuss in detail surprising kinematic features of this process, focusing on spinless Particle annihilation. They include (1) a new dimension in the final momentum space available in twisted annihilation, (2) interference fringes emerging in the cross section as a function of the total energy, and (3) the built-in mass spectrometric capability of this process, that is, simultaneous production and automatic angular separation of several resonances with different masses in monochromatic twisted Particle annihilation experiment running at fixed energy. All these features cannot be obtained in the usual plane wave collision setting.