Institut für Theoretische Physik II: Weiche Materie, Heinrich, Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany.
University of Lille, UGSF CNRS UMR8576, 59000, Lille, France.
Eur Phys J E Soft Matter. 2022 Mar 1;45(3):18. doi: 10.1140/epje/s10189-022-00176-4.
We discuss the dynamics of a Brownian particle under the influence of a spatially periodic noise strength in one dimension using analytical theory and computer simulations. In the absence of a deterministic force, the Langevin equation can be integrated formally exactly. We determine the short- and long-time behaviour of the mean displacement (MD) and mean-squared displacement (MSD). In particular, we find a very slow dynamics for the mean displacement, scaling as [Formula: see text] with time t. Placed under an additional external periodic force near the critical tilt value we compute the stationary current obtained from the corresponding Fokker-Planck equation and identify an essential singularity if the minimum of the noise strength is zero. Finally, in order to further elucidate the effect of the random periodic driving on the diffusion process, we introduce a phase factor in the spatial noise with respect to the external periodic force and identify the value of the phase shift for which the random force exerts its strongest effect on the long-time drift velocity and diffusion coefficient.
我们使用解析理论和计算机模拟讨论了一维空间中受空间周期性噪声强度影响的布朗粒子的动力学。在没有确定力的情况下,朗之万方程可以进行形式上的精确积分。我们确定了平均位移(MD)和均方位移(MSD)的短时间和长时间行为。特别是,我们发现平均位移的动力学非常缓慢,与时间 t 呈[公式:见文本]比例。在接近临界倾斜值的外加周期性力的作用下,我们从相应的福克-普朗克方程中计算出得到的稳态电流,并确定了如果噪声强度的最小值为零,则存在本质奇点。最后,为了进一步阐明随机周期性驱动对扩散过程的影响,我们在空间噪声中引入相对于外部周期性力的相位因子,并确定相位移动的值,在此值下随机力对长时间漂移速度和扩散系数的影响最大。