Whitfield Carl A, Marenduzzo Davide, Voituriez Raphaël, Hawkins Rhoda J
Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, S3 7RH, Sheffield, UK,
Eur Phys J E Soft Matter. 2014 Feb;37(2):8. doi: 10.1140/epje/i2014-14008-3. Epub 2014 Feb 18.
We present a continuum level analytical model of a droplet of active contractile fluid consisting of filaments and motors. We calculate the steady state flows that result from a splayed polarisation of the filaments. We account for interaction with the external medium by imposing a viscous friction at the fixed droplet boundary. We then show that the droplet has non-zero force dipole and quadrupole moments, the latter of which is essential for self-propelled motion of the droplet at low Reynolds' number. Therefore, this calculation describes a simple mechanism for the motility of a droplet of active contractile fluid embedded in a three-dimensional environment, which is relevant to cell migration in confinement (for example, embedded within a gel or tissue). Our analytical results predict how the system depends on various parameters such as the effective friction coefficient, the phenomenological activity parameter and the splay of the imposed polarisation.
我们提出了一个由细丝和马达组成的活性收缩流体微滴的连续介质水平分析模型。我们计算了细丝呈扇形极化所产生的稳态流动。通过在固定的微滴边界施加粘性摩擦来考虑与外部介质的相互作用。然后我们表明，该微滴具有非零的力偶极矩和四极矩，其中后者对于微滴在低雷诺数下的自推进运动至关重要。因此，该计算描述了嵌入三维环境中的活性收缩流体微滴运动的一种简单机制，这与受限环境中的细胞迁移（例如，嵌入凝胶或组织中）相关。我们的分析结果预测了该系统如何依赖于各种参数，如有效摩擦系数、唯象活性参数和外加极化的扇形程度。
