发表机构
Indian Institute of Science Education and Research Mohali（印度科学教育研究所莫哈利分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过求解可压缩涨落流体动力学问题，发现热布朗粒子有效温度在声波波长与粒子半径相当时出现声学凹陷，其位置由$a\omega/c$决定，深度由粘性-声学衰减长度控制，表明可压缩性可降低动力学噪声温度。
AI 中文摘要
热布朗粒子受非均匀加热溶剂的热涨落驱动，因此遵循具有频率依赖有效温度的涨落-耗散关系。现有理论假设溶剂不可压缩。我们证明，有限声速在动力学区域内定性改变该有效温度。通过求解加热球体的可压缩涨落流体动力学问题，我们发现当声波波长与粒子半径相当时，有效噪声温度出现显著的声学凹陷。该凹陷的产生是因为弱衰减的纵模在耗散前将机械能带离加热表面，从而使耗散被温度场中较冷区域加权。其位置由$a\omega/c=\mathcal{O}(1)$决定，而其深度由无量纲的粘性-声学衰减长度$a_c/a$控制。该结果在热布朗运动中识别出一个声学窗口，在此窗口中，可压缩性降低而非升高动力学噪声温度。
英文摘要
A hot Brownian particle is driven by thermal fluctuations from a nonuniformly heated solvent and therefore obeys a fluctuation-dissipation relation with a frequency-dependent effective temperature. Existing theories assume an incompressible solvent. We show that finite sound speed qualitatively changes this effective temperature in the kinetic regime. Solving the compressible fluctuating-hydrodynamic problem for a heated sphere, we find that the effective noise temperature develops a pronounced acoustic dip when the sound wavelength becomes comparable to the particle radius. The dip occurs because weakly attenuated longitudinal modes carry mechanical energy away from the heated surface before it is dissipated, so that the dissipation is weighted by colder regions of the temperature field. Its position is set by $aω/c=\mathcal{O}(1)$, while its depth is controlled by the dimensionless viscous-acoustic attenuation length $a_c/a$. The result identifies an acoustic window in hot Brownian motion in which compressibility lowers, rather than raises, the kinetic noise temperature.
