论文标题
细胞流中的植物：从增强的分散到阻塞
Phoresis in cellular flows: from enhanced dispersion to blockage
论文作者
论文摘要
在本文中，我们从数值上研究了胶体在施加的平均盐梯度存在下胶体在二维细胞流中的分散。由于额外的标量，胶体不完全遵循欧拉流场，而是（小）超速性，与盐梯度成正比，$ \ mathbf {v} _ \ mathrm {dp} =α\ nabla s $，其中$α$是$α$是Phoretic常数和$ $ $ $ $ $ $ $ $。我们研究了胶体的均匀分布的解散，以及它们的长期平均速度$ \ mathbf {v_m} $以及有效的扩散率$ d_ \ mathrm {eff} $受Phoretic漂移的影响。我们观察到胶体动力学的两个机制，具体取决于阻塞标准$ r =αgl/\ sqrt {4 d_cd_s} $，其中$ g $是平均盐梯度振幅，$ l $流量的长度和$ d_c $和$ d_c $ and $ d_s $ d_s $ d_s $ d_s $ d_s $ d_s $ d_s $ d_s $ d_s $ d_s $ colloids and salt colloids and Salt。当$ r <1 $时，平均速度可以通过$ v_m \ proptoαg\ sqrt {pe_s} $，$ pe_s $是盐péclet编号。当$ r> 1 $时，由于流动漂移而引起的可压缩效应是如此之强，以至于沿抑制细胞向细胞运输的分离菌会耗尽胶体的耗竭。
In this article, we study numerically the dispersion of colloids in a two-dimensional cellular flow in the presence of an imposed mean salt gradient. Owing to the additional scalar, the colloids do not follow exactly the Eulerian flow field, but have a (small) extra-velocity proportional to the salt gradient, $\mathbf{v}_\mathrm{dp}=α\nabla S$, where $α$ is the phoretic constant and $S$ the salt concentration. We study the demixing of an homogenous distribution of colloids and how their long-term mean velocity $\mathbf{V_m}$ and effective diffusivity $D_\mathrm{eff}$ are influenced by the phoretic drift. We observe two regimes of colloids dynamics depending on a blockage criterion $R=αG L/\sqrt{4 D_cD_s}$, where $G$ is the mean salt gradient amplitude, $L$ the length scale of the flow and $D_c$ and $D_s$ the molecular diffusivities of colloids and salt. When $R<1$, the mean velocity is strongly enhanced with $V_m \propto αG \sqrt{Pe_s}$, $Pe_s$ being the salt Péclet number. When $R> 1$, the compressibility effect due to the phoretic drift is so strong that a depletion of colloids occurs along the separatrices inhibiting cell-to-cell transport.
