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. / Master of Science / 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.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/112551 |
| Date | 18 May 2021 |
| Creators | Kowalski, Nicholas Gerald |
| Contributors | Mechanical Engineering, Boreyko, Jonathan B., Cheng, Jiangtao, Shahab, Shima |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, video/mp4, video/mp4, video/mp4, video/mp4 |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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