Date of Award


Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Mathematical Sciences (PhD)

Administrative Home Department

Department of Mathematical Sciences

Advisor 1

Kathleen A Feigl

Advisor 2

Franz X Tanner

Committee Member 1

Alexander Labovsky

Committee Member 2

Song L Yang


Computational models are developed to investigate peristaltic motion in the human gastro-intestinal tract. The peristaltic motion is simulated by means of traveling waves which deform the boundary of the tubes. An axisymmetric tube of uniform diameter is used to model the small intestines, and an axisymmetric conical geometry is developed to model the lower part of the human stomach. The conical geometry represents a simplification of the more complicated three-dimensional models of the human stomach that have been used in other studies. Also, they seeks to reduce computational costs and circumvent difficulties of mesh generation. The computations are performed within the open source CFD environment OpenFOAM. Whenever possible, comparisons are made to the predictions of other geometrical models from the literature to validate our results. First, the transport of fluids via peristaltic motion in a cylindrical or a conical tube is investigated. The effect of fluid, and geometrical parameters on the ow behavior is determined. Of particular interest is the transport efficiency, ow patterns, and strain rates. Second, the mixing characteristics of peristalsis is investigated for the human stomach when the pylorus is closed. Using the axisymmetric conical geometry, the effect of parameters such as wave speed, wave shape, relative occlusion, and fluid viscosity of Newtonian and non-Newtonian fluids on the ow behavior are determined. The focus of these investigations is on the quantification of the retropulsive jet induced at the pylorus, as well as on the induced vorticities between peristaltic waves, both of which contribute to the mixing efficiency. Moreover, particle tracking techniques are used to determine strain rates along particle paths which allows the investigation of stresses experienced by food particles.