湍流磁普朗特数和磁扩散率猝灭的数值模拟
Turbulent magnetic Prandtl number and magnetic diffusivity quenching from simulations
摘要：
强迫湍流模拟用于确定湍流运动粘度，nu_t，从大尺度速度场的衰减率。同样，湍流磁扩散率eta_t由大尺度磁场的衰减确定。在运动学区域，当磁场较弱时，湍流磁普朗特数nu_t/eta_t约为1。当磁场为非螺旋场时，当磁能和动能变得相当时，eta_t被淬灭。对于螺旋场，猝灭较强，可用动力学猝灭公式描述。
英文摘要：
Forced turbulence simulations are used to determine the turbulent kinematic viscosity, nu_t, from the decay rate of a large scale velocity field. Likewise, the turbulent magnetic diffusivity, eta_t, is determined from the decay of a large scale magnetic field. In the kinematic regime, when the field is weak, the turbulent magnetic Prandtl number, nu_t/eta_t, is about unity. When the field is nonhelical, eta_t is quenched when magnetic and kinetic energies become comparable. For helical fields the quenching is stronger and can be described by a dynamical quenching formula.
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