Garrett, Joel Frederick2021-01-082021-01-082021-01-07vt_gsexam:27773http://hdl.handle.net/10919/101784In this dissertation, we examine how advective and diffusive flows are created in the insect respiratory system, using a combination of direct biological studies and computational fluid dynamics simulations. The insect respiratory system differs significantly from the vertebrate respiratory system. While mammals use oxygen-carrying molecules such as hemoglobin, insects do not, favoring the direct delivery of oxygen to the tissues. An insect must balance advective flow with diffusive flux in order to sustain the appropriate oxygen concentrations at the tissue level. To better understand flow creation mechanisms, we studied the Madagascar hissing cockroach. In Chapter One, we used x-ray imaging to identify how tracheal tube compression, spiracular valving, and abdominal pumping coordinate to produce unidirectional flow during active respiration. In Chapter Two, we altered the environmental conditions by exposing the animals to various levels of hypoxia and hyperoxia, then examined how they changed their respiratory behaviors. In Chapter Three, we used our previous findings to construct a simulated insect respiratory system to parametrically study the effects of network geometry and valve timing on the creation of unidirectional advective flow and diffusive flux. These results can be used to inform future studies of the insect respiratory system, as well as act as the basis for bio-inspired microfluidic devices.ETDIn CopyrightmicrofluidicsentomologyengineeringSimulationDissertation