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Henning Struchtrup - One of the best experts on this subject based on the ideXlab platform.

  • ellipsoidal statistical bhatnagar gross krook model with velocity dependent Collision Frequency
    Physics of Fluids, 2005
    Co-Authors: Yingsong Zheng, Henning Struchtrup
    Abstract:

    In this paper, an ellipsoidal statistical (ES) Bhatnagar–Gross–Krook (BGK)-type kinetic model with velocity-dependent Collision Frequency is proposed and further numerically tested for one-dimensional shock waves and planar Couette flow at steady state for hard sphere molecules. In this new kinetic model, a physically meaningful expression for the velocity-dependent Collision Frequency derived from the Boltzmann equation is used, while the important properties for a kinetic model are retained at the same time. This kinetic model can be simplified to the classical ES-BGK model and the BGK model with velocity-dependent Collision Frequency for suitable choices of parameters. The H theorem for this new kinetic model has so far been proven only for small Knudsen numbers. The numerical method used here for kinetic models is based on Mieussens’s discrete velocity model [L. Mieussens, J. Comput. Phys. 162, 429 (2000)]. Computational results from the kinetic models (including the BGK model, the ES-BGK model, the B...

  • Numerical Solutions For The BGK‐Model With Velocity‐Dependent Collision Frequency
    AIP Conference Proceedings, 2003
    Co-Authors: Luc Mieussens, Henning Struchtrup
    Abstract:

    The BGK‐model with velocity dependent Collision Frequency is discussed and applied to Couette flow and the shock structure problem. Thermal conductivity and viscosity are computed from the Chapman‐Enskog method and several velocity‐dependent Collision frequencies are introduced which all give the proper Prandtl number. The models are tested and compared to results from the Direct Simulation Monte Carlo method. The simulations rely on a numerical scheme that ensures positivity of solutions, conservation of moments, and dissipation of entropy. The advantages and disadvantages of the various BGK models are discussed.

  • numerical solutions for the bgk model with velocity dependent Collision Frequency
    RAREFIED GAS DYNAMICS: 23rd International Symposium, 2003
    Co-Authors: Luc Mieussens, Henning Struchtrup
    Abstract:

    The BGK‐model with velocity dependent Collision Frequency is discussed and applied to Couette flow and the shock structure problem. Thermal conductivity and viscosity are computed from the Chapman‐Enskog method and several velocity‐dependent Collision frequencies are introduced which all give the proper Prandtl number. The models are tested and compared to results from the Direct Simulation Monte Carlo method. The simulations rely on a numerical scheme that ensures positivity of solutions, conservation of moments, and dissipation of entropy. The advantages and disadvantages of the various BGK models are discussed.

  • the bgk model with velocity dependent Collision Frequency
    Continuum Mechanics and Thermodynamics, 1997
    Co-Authors: Henning Struchtrup
    Abstract:

    We consider the BGK-model with velocity dependent Collision Frequency. By use of the Chapman-Enskog method we calculate thermal conductivity and viscosity. We show that a simple power law for the Collision Frequency may lead to the proper Prandtl number. Moreover we use Grad’s moment method to calculate thermal conductivity and viscosity. We show that the results of both methods coincide if Grad’s method is based on a large number of moments.

Benjamin A Jorns - One of the best experts on this subject based on the ideXlab platform.

Akira Matsugi - One of the best experts on this subject based on the ideXlab platform.

  • Collision Frequency for Energy Transfer in Unimolecular Reactions
    The journal of physical chemistry. A, 2018
    Co-Authors: Akira Matsugi
    Abstract:

    Pressure dependence of unimolecular reaction rates is governed by the energy transfer in Collisions of reactants with bath gas molecules. Pressure-dependent rate constants can be theoretically determined by solving master equations for unimolecular reactions. In general, master equation formulations describe energy transfer processes using a Collision Frequency and a probability distribution model of the energy transferred per Collision. The present study proposes a novel method for determining the Collision Frequency from the results of classical trajectory calculations. Classical trajectories for Collisions of several polyatomic molecules (ethane, methane, tetrafluoromethane, and cyclohexane) with monatomic colliders (Ar, Kr, and Xe) were calculated on potential energy surfaces described by the third-order density-functional tight-binding method in combination with simple pairwise interaction potentials. Low-order (including non-integer-order) moments of the energy transferred in deactivating Collisions...

Yingjie Ling - One of the best experts on this subject based on the ideXlab platform.

  • Propagation of terahertz electromagnetic wave in plasma with inhomogeneous Collision Frequency
    Physics of Plasmas, 2014
    Co-Authors: Yuan Tian, Yiping Han, Yingjie Ling
    Abstract:

    In this paper, we investigate the absorption spectra of terahertz electromagnetic wave in plasma with inhomogeneous Collision Frequency. Profiles are introduced to describe the non-uniformity of Collision Frequency. It is interesting to find that when the plasma is Collision Frequency inhomogeneous, the absorption spectrum would decreases faster than that in uniform plasma. And the rate of decreasing would be different when the profile changes. Two parameters are set up to predict how the profiles affect the absorption spectra. Furthermore, the effects of electron density are also considered.

Ethan T Dale - One of the best experts on this subject based on the ideXlab platform.