Department of Physics and ITST, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
Phys Rev Lett. 2011 Jun 17;106(24):244502. doi: 10.1103/PhysRevLett.106.244502. Epub 2011 Jun 15.
We report data for nonequilibrium density fluctuations in a layer of liquid CS(2) subjected to temperature gradients on Earth and in a satellite. The structure factor S(q) was measured using a calibrated shadowgraph. Upon removing gravity, S(q) increased dramatically at small wave vector, until the fluctuations generated by thermal noise were limited only by the 3 mm sample thickness. The results agree with theory to within a few percent on Earth and are ∼14% below theory in microgravity, demonstrating that the use of equilibrium Langevin forces is appropriate in this nonequilibrium situation.
我们报告了在地球和卫星上的温度梯度下，一层液态 CS(2)中的非平衡密度涨落的数据。使用校准的阴影图测量了结构因子 S(q)。在消除重力后，在小波矢处 S(q)急剧增加，直到由热噪声产生的涨落仅受 3mm 样品厚度的限制。结果与地球表面的理论值相差几个百分点，在微重力下与理论值相差约 14%，这表明在这种非平衡情况下，平衡朗之万力的使用是合适的。
