The propagation of intense rectangular thermal pulses in superfluid helium is studied numerically using superfluid turbulence hydrodynamics with various equations for vortex line density dynamics. It is shown that the experimental data are most adequately described by the Vinen equation. The impact of the background vortex line density on the dynamics of the pulses at different temperatures of the unperturbed fluid is studied by using the Vinen equation that describes the vortex line density dynamics. It is found that a high background vortex line density leads to a significant change in the pulse shape and overheating of the fluid. At the same values of the heat flux supplied to the heater and the background vortex line density, the temperature perturbations decrease with the increasing temperature of the unperturbed fluid. This is due to changes in the thermodynamic properties of the fluid and the vortex line density dynamics. As the temperature increases, the increase in the vortex line density slows down, as a result of which the fluid temperature perturbations decrease significantly.

中文翻译：

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超流氦中的涡线密度和热脉冲动力学

使用超流湍流流体动力学和各种涡线密度动力学方程，对超流氦中强矩形热脉冲的传播进行了数值研究。结果表明，实验数据最能用 Vinen 方程来描述。利用描述涡线密度动力学的Vinen方程，研究了背景涡线密度对未扰动流体不同温度下脉冲动力学的影响。发现高背景涡线密度导致脉冲形状的显着变化和流体过热。在提供给加热器的热通量和背景涡线密度相同的值下，温度扰动随着未扰动流体温度的升高而减小。这是由于流体的热力学性质和涡线密度动力学发生了变化。随着温度的升高，涡线密度的增加减慢，因此流体温度扰动显着降低。