Modeling the filtration efficiency of a woven fabric: The role of multiple lengthscales.

IF 2 4区管理学 Q2 BUSINESS, FINANCE

Accounting and Business Research Pub Date : 2022-03-01 DOI:10.1063/5.0074229

Ioatzin Rios de Anda, Jake W Wilkins, Joshua F Robinson, C Patrick Royall, Richard P Sear

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Abstract

During the COVID-19 pandemic, many millions have worn masks made of woven fabric to reduce the risk of transmission of COVID-19. Masks are essentially air filters worn on the face that should filter out as many of the dangerous particles as possible. Here, the dangerous particles are the droplets containing the virus that are exhaled by an infected person. Woven fabric is unlike the material used in standard air filters. Woven fabric consists of fibers twisted together into yarns that are then woven into fabric. There are, therefore, two lengthscales: the diameters of (i) the fiber and (ii) the yarn. Standard air filters have only (i). To understand how woven fabrics filter, we have used confocal microscopy to take three-dimensional images of woven fabric. We then used the image to perform lattice Boltzmann simulations of the air flow through fabric. With this flow field, we calculated the filtration efficiency for particles a micrometer and larger in diameter. In agreement with experimental measurements by others, we found that for particles in this size range, the filtration efficiency is low. For particles with a diameter of 1.5 μm, our estimated efficiency is in the range 2.5%-10%. The low efficiency is due to most of the air flow being channeled through relatively large (tens of micrometers across) inter-yarn pores. So, we conclude that due to the hierarchical structure of woven fabrics, they are expected to filter poorly.

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编织物过滤效率建模：多重长度尺度的作用

在 COVID-19 大流行期间，数百万人戴上了编织物制成的口罩，以降低 COVID-19 的传播风险。口罩本质上是戴在脸上的空气过滤器，应尽可能多地过滤掉危险微粒。这里的危险微粒是指感染者呼出的含有病毒的飞沫。编织物与标准空气过滤器所用的材料不同。编织物由纤维捻成纱线，然后编织成织物。因此有两个长度尺度：(i) 纤维直径和 (ii) 纱线直径。标准的空气过滤器只有（i）。为了了解编织物是如何过滤的，我们使用共聚焦显微镜拍摄了编织物的三维图像。然后，我们利用图像对穿过织物的气流进行晶格玻尔兹曼模拟。通过这个流场，我们计算出了直径为一微米或更大颗粒的过滤效率。与其他人的实验测量结果一致，我们发现对于这个尺寸范围内的颗粒，过滤效率很低。对于直径为 1.5 微米的颗粒，我们估计的过滤效率在 2.5%-10% 之间。效率低的原因是大部分气流通过了相对较大（直径数十微米）的纱线间孔隙。因此，我们得出结论，由于编织物的分层结构，预计其过滤效果较差。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Accounting and Business Research BUSINESS, FINANCE-

CiteScore

3.40

自引率

11.80%

发文量

期刊介绍： Accounting and Business Research publishes papers containing a substantial and original contribution to knowledge. Papers may cover any area of accounting, broadly defined and including corporate governance, auditing and taxation. However the focus must be accounting, rather than (corporate) finance or general management. Authors may take a theoretical or an empirical approach, using either quantitative or qualitative methods. They may aim to contribute to developing and understanding the role of accounting in business. Papers should be rigorous but also written in a way that makes them intelligible to a wide range of academics and, where appropriate, practitioners.