Show simple item record

dc.contributor.advisorHu, David L.
dc.contributor.authorYang, Patricia
dc.date.accessioned2018-05-31T18:17:02Z
dc.date.available2018-05-31T18:17:02Z
dc.date.created2018-05
dc.date.issued2018-04-23
dc.date.submittedMay 2018
dc.identifier.urihttp://hdl.handle.net/1853/59937
dc.description.abstractThe intake of food and water and its excretion is a hallmark of all life forms. However, the mechanics dictating efficient transport of wastes from the body remains poorly understood. In this thesis, we investigate the transport of urine and feces in over 40 species of mammals. We employ a combination of urine and feces collections at Zoo Atlanta and theoretical models based on those collections. We pay particular attention to the governing principles for reducing energy, time, and applied force. We discover that the urethra serves as a siphon to accelerate urine flow by gravity, enabling the urinary system to be enlarged by a factor of 3,600 without compromising its function. As a result, large mammals such as elephants urinate in the same duration of 21 seconds as their smaller counterparts, such as cats. Our model clarifies the contributions of bladder pressure and gravity as a function of body size. The ability to excrete materials quickly regardless of body size is also exhibited in defecation, which lasts an average of 12 seconds. We measure the defecation speeds of mammals and the mucus evaporation on feces. Larger animals have thicker mucus layers that enable them to release more feces in the same time as smaller animals. Lastly, we present experiments and theory regarding the rhythmic motions within the small intestine of rats. We show that the frequency of motion is higher farther from the stomach. We rationalize this motion based on the higher occurrence of bubbles that lower the density of gut content and thus increase the resonant frequency of the intestine. This thesis sheds light on optimal transport strategies in soft tissue and provides a design principle of scalable hydrodynamic systems.
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherGeorgia Institute of Technology
dc.subjectUrology
dc.subjectAllometry
dc.subjectScaling
dc.subjectBernoulli's principle
dc.subjectFeces
dc.subjectLubrication
dc.subjectMucus
dc.subjectSegmental contraction
dc.subjectIntestinal mobility
dc.subjectThrust
dc.subjectBackground flow
dc.titleHydrodynamics of urination and digestion
dc.typeDissertation
dc.description.degreePh.D.
dc.contributor.departmentMechanical Engineering
thesis.degree.levelDoctoral
dc.contributor.committeeMemberAlexeev, Alexander
dc.contributor.committeeMemberKu, David
dc.contributor.committeeMemberDixon, Brandon
dc.contributor.committeeMemberFenton, Flavio
dc.date.updated2018-05-31T18:17:02Z


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record