76th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 19–21, 2023;
Washington, DC
Session X35: Multiphase Flows: General III
8:00 AM–10:36 AM,
Tuesday, November 21, 2023
Room: 202A
Chair: Olivier Coutier-Delgosha, Graduate Advisor
Abstract: X35.00003 : Exploring Aerosol-Gas Dynamics in Fluidic Oscillator Ventilation
8:26 AM–8:39 AM
Abstract
Presenter:
Ryan S Learn
(Liberty University)
Authors:
Ryan S Learn
(Liberty University)
Wayne Strasser
(Liberty University)
The reality of infectious disease and the threat of biological and chemical weapons—all of which can cause respiratory depression or failure—have become more apparent in the wake of COVID-19. Battlefield resuscitation and pre-hospital care utilize a bag valve mask (BVM) to provide positive pressure ventilation for patients with inadequate breaths, though this tool is not ideal due to its inconsistency and heavy resource load. A fluidic logic oscillating ventilator (FLOV) is a pocket-sized device that achieves the same goal while self-sustaining within safe breathing parameters. The source of energy is a constant motive flow passing through a constricting nozzle and further into a region of expansion. "Searching vortices" form due to instabilities in this expansion field and they "pick" a direction for aiming the bulk flow. This results in a natural oscillation between the patient and exhaust. This technology holds great potential in pre-hospital care if droplets are introduced to the flow, as aerosol inhalation therapy can be used to administer many life-saving medications. Investigations were conducted to learn the gas' effects on droplets (feed-forward) and the droplets' effects on the carrier gas (feedback) in compressible transitional flows. While feed-forward is expected and will affect the exit aerosol distribution, it is the feedback effect that might result in unintended negative consequences in FLOV performance. Variables such as droplet size, flow rate, and numerical parameters were considered. It was found that there was a threshold of droplet size below which the droplets did not modify the vortices, but the feedback threshold was affected by droplet concentration. We aim to produce a "safety" map to help users define a safe operating range for administering treatment via the FLOV.