Droplet spreading on chemically heterogeneous substrates.
Droplet spreading on chemically heterogeneous substrates.
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DOI：
10.1103/physreve.84.036305
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发表时间：
2011-09
期刊：
影响因子：
--
通讯作者：
R. Vellingiri;N. Savva;S. Kalliadasis
中科院分区：
文献类型：
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作者：
R. Vellingiri;N. Savva;S. Kalliadasis
考虑二维液滴在化学异质衬底上的扩散动力学。假设小斜率和强表面张力效应，斯托克斯方程的长波展开产生液滴厚度的单一演化方程。通过假设液-固界面处存在滑移，消除了接触线奇异性。基材的化学性质通过微观接触角的局部变化来并入，其作为控制方程中的边界条件出现。通过渐近匹配的流量在大部分的液滴的接触线附近的流量，我们得到一组耦合的常微分方程的位置的两个液滴前。我们验证我们的匹配过程的有效性，通过比较的解决方案的常微分方程与解决方案的完整的控制方程。液滴动力学通过相平面分析详细检查。一些有趣的功能，不存在于化学均匀的基板被发现，如存在多个平衡，钉扎的液滴前端在本地化的化学功能，和液滴前端表现出粘滑行为的可能性。
Consider the spreading dynamics of a two-dimensional droplet over chemically heterogeneous substrates. Assuming small slopes and strong surface tension effects, a long-wave expansion of the Stokes equations yields a single evolution equation for the droplet thickness. The contact line singularity is removed by assuming slip at the liquid-solid interface. The chemical nature of the substrate is incorporated by local variations in the microscopic contact angle, which appear as boundary conditions in the governing equation. By asymptotically matching the flow in the bulk of the droplet with the flow in the vicinity of the contact lines, we obtain a set of coupled ordinary differential equations for the locations of the two droplet fronts. We verify the validity of our matching procedure by comparing the solutions of the ordinary differential equations with solutions of the full governing equation. The droplet dynamics is examined in detail via a phase-plane analysis. A number of interesting features that are not present in chemically homogeneous substrates are found, such as the existence of multiple equilibria, the pinning of the droplet fronts at localized chemical features, and the possibility for the droplet fronts to exhibit a stick-slip behavior.