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arXiv 1404.2181cond-mat.stat-mechphysics.data-an
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扩散控制吸收中的第一入侵者动力学

First Invader Dynamics in Diffusion-Controlled Absorption

S. Redner, Baruch Meerson

摘要:

我们调查的平均时间为最早的粒子击中一个球形吸收体时,一个均匀的气体的自由扩散的粒子密度$ρ$和扩散率$D$是在一个确定性的状态下制备的,最初由一个最小的距离$\ell$从这个吸收体分离。在高密度极限下,第一次吸收时间在一维中与$\frac{\ell^2}{D}\frac{1}{\lnρ\ell}$成比例;我们还得到了三维中的第一次吸收时间。在一维中,我们确定了最接近$k^{\rm th}$的粒子是第一个击中吸收体的粒子的概率。在大的$k$下,该概率衰减为$k^{1/3}\exp(-Ak^{2/3})$,其中$A= 1.93299\ldots$可解析计算。作为推论,$k^{\rm th}$ -最接近粒子的特征命中时间$T_k$与$k^{4/3}$成比例;这对应于超扩散但仍然是亚弹道运动。

英文摘要:

We investigate the average time for the earliest particle to hit a spherical absorber when a homogeneous gas of freely diffusing particles with density $ρ$ and diffusivity $D$ is prepared in a deterministic state and is initially separated by a minimum distance $\ell$ from this absorber. In the high-density limit, this first absorption time scales as $\frac{\ell^2}{D}\frac{1}{\lnρ\ell}$ in one dimension; we also obtain the first absorption time in three dimensions. In one dimension, we determine the probability that the $k^{\rm th}$-closest particle is the first one to hit the absorber. At large $k$, this probability decays as $k^{1/3}\exp(-Ak^{2/3})$, with $A= 1.93299\ldots$ analytically calculable. As a corollary, the characteristic hitting time $T_k$ for the $k^{\rm th}$-closest particle scales as $k^{4/3}$; this corresponds to superdiffusive but still subballistic motion.

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