Fog Harps: Elastocapillarity, Droplet Dynamics, and Optimization

Kowalski, Nicholas Gerald

Fog Harps: Elastocapillarity, Droplet Dynamics, and Optimization

dc.contributor.author	Kowalski, Nicholas Gerald	en
dc.contributor.committeechair	Boreyko, Jonathan B.	en
dc.contributor.committeemember	Cheng, Jiangtao	en
dc.contributor.committeemember	Shahab, Shima	en
dc.contributor.department	Mechanical Engineering	en
dc.date.accessioned	2022-11-10T07:00:12Z	en
dc.date.available	2022-11-10T07:00:12Z	en
dc.date.issued	2021-05-18	en
dc.description.abstract	Fog harvesting is emerging as a promising means to ease the water shortage crisis in arid regions of the world with ample fog. The current state-of-the-art for fog harvesting is mesh netting, which is accessible yet struggles from a dual constraint: a course mesh lets most microscopic fog droplets pass through it, while a fine mesh clogs. In recent years, fog harps have been gaining attention as a superior alternative to meshes, bypassing these inherent constraints. In this work, we expand upon previous fog harp research with a focus on optimization. First, we analyze wire tangling in a harp due to capillary forces, resulting in a mathematical model that is able to predict when wire tangling will occur. Second, we systematically vary three key parameters of a fog harp (wire material, center-to-center wire pitch, and wire length), arriving at an optimal combination. Finally, we develop a numerical model to describe the dynamics of a fog droplet sliding down a harp wire while coalescing with others littered along it. By applying all knowledge acquired through these studies, the next generation of fog harps will push the performance ceiling of practical fog harvesters higher than ever.	en
dc.description.abstractgeneral	The human population continues to grow, and with it the demand for fresh water. This need has caused many to turn to unconventional sources of water, including fog (the suspension of microscopic liquid water droplets in the air). Fog harvesters already exist in arid regions of the world as mesh nets, but suffer dual constraints from their grid-like structure: course meshes fail to capture most fog droplets passing through, while fine meshes get clogged. To bypass these inherent limits, we turn to nature for a solution. It has been observed that California redwood trees are able to effectively collect fog on their straight leaf needles, dripping droplets to the roots below. Inspired by this, we fabricate a device called a fog harp, which removes the impeding horizontal wires of meshes to effectively capture and slide droplets down its vertical wires. In this work, we expand upon previous fog harp research by investigating ways to optimize its water collection efficiency. First, we develop a mathematical model to describe the tangling of harp wires due to merging droplets on adjacent wires pulling them together. Second, we systematically vary three key parameters of the fog harp (wire material, center-to-center wire spacing, and wire length) to arrive at the optimal combination. Finally, we develop a model to describe the dynamics of droplets sliding down harp wires while merging with others littered along it. These studies will raise the performance ceiling of fog harps and push them to real-world applications.	en
dc.description.degree	Master of Science	en
dc.format.medium	ETD	en
dc.identifier.other	vt_gsexam:30603	en
dc.identifier.uri	http://hdl.handle.net/10919/112551	en
dc.publisher	Virginia Tech	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	fog harvesting	en
dc.subject	fog harp	en
dc.subject	wire tangling	en
dc.subject	droplet	en
dc.subject	elastocapillary	en
dc.title	Fog Harps: Elastocapillarity, Droplet Dynamics, and Optimization	en
dc.type	Thesis	en
thesis.degree.discipline	Mechanical Engineering	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	masters	en
thesis.degree.name	Master of Science	en