Motivated by the fact that the drying time of respiratory droplets is related to the spread of COVID-19 [R. Bhardwaj and A. Agrawal, “Likelihood of survival of coronavirus in a respiratory droplet deposited on a solid surface,” Phys. Fluids 32, 061704, (2020)], we analyze the drying time of droplets ejected from a COVID-19 infected subject on surfaces of personal protection equipment (PPE), such as a face mask, of different wettabilities. We report the ratio of drying time of the droplet on an ideal superhydrophobic surface (contact angle, θ → 180°) to an ideal hydrophilic surface (θ → 0°) and the ratio of the maximum to minimum drying time of the droplet on the surfaces with different contact angles. The drying time is found to be maximum if θ = 148°, while the aforementioned ratios are 4.6 and 4.8, respectively. These ratios are independent of the droplet initial volume, ambient temperature, relative humidity, and thermophysical properties of the droplet and water vapor. We briefly examine the change in drying time in the presence of impurities on the surface. Besides being of fundamental interest, the analysis provides insights that are useful while designing the PPE to tackle the present pandemic.

中文翻译：

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调整表面润湿性以减少呼吸道飞沫感染 COVID-19 的机会并提高个人防护设备的有效性


其动机是呼吸道飞沫的干燥时间与 COVID-19 的传播有关 [R. Bhardwaj 和 A. Agrawal，“冠状病毒在沉积在固体表面的呼吸道飞沫中的存活可能性”，Phys。 Fluids 32, 061704, (2020)]，我们分析了从 COVID-19 感染者喷出的液滴在不同润湿性的个人防护装备 (PPE)（例如口罩）表面上的干燥时间。我们报告了理想超疏水表面（接触角，θ → 180°）上的液滴与理想亲水表面（θ → 0°）上的液滴干燥时间之比，以及液滴在理想超疏水表面（接触角，θ → 180°）上的干燥时间的最大与最小之比。具有不同接触角的表面。当θ=148°时，干燥时间最大，而上述比率分别为4.6和4.8。这些比率与液滴初始体积、环境温度、相对湿度以及液滴和水蒸气的热物理性质无关。我们简要检查表面存在杂质时干燥时间的变化。除了具有根本意义之外，该分析还提供了在设计个人防护装备以应对当前流行病时有用的见解。