CFD of the aerodynamics of fog harp water harvesters

Presenter: Daniel Sam Binu, Aerospace and Ocean Engineering

Authors: D. Binu, J. Kaindu, J. Boreyko, C. Roy

Abstract: The aerodynamics of fog water harvesting is understudied. To address this, we use CFD simulations and an analytical flow model to predict fog harvester performance. We focus on fog harps (vertical wire arrays), as they outperform conventional meshes. We study 9 cases with flow velocities of 0.1, 1.0, and 10.0 m/s and harp widths of 10, 100, and 1000 wires. We quantify flowthrough efficiency (FE) as the ratio of mass flow rate through the harp to that of an unobstructed domain. FE values for 10, 100, and 1000 wires are 10.2%, 16.0%, and 10.0% at 0.1 m/s; 50.0%, 53.5%, and 43.34% at 1.0 m/s; and 64.0%, 74.2%, and 67.2% at 10.0 m/s. From 10 to 100 wires, FE increases by factors of 1.6, 1.1, and 1.2 at 0.1, 1.0, and 10.0 m/s, respectively; increasing to 1000 wires reduces FE by factors of 0.6, 0.8, and 0.9. This non-monotonic trend results from competing effects of increased flow paths and enhanced wake interactions. At constant wire count, increasing velocity significantly improves FE. From 0.1 to 1.0 m/s, FE increases by factors of 5.0, 3.4, and 4.3 for 10, 100, and 1000 wires, respectively; from 1.0 to 10.0 m/s, the corresponding increases are by factors of 1.3, 1.4, and 1.5. Thus, revealing the dominant role of flow velocity in enhancing water collection-not reported previously.