Gastric Digestion of Foods: Mathematical Modeling of Flow Field in a Human Stomach

Abstract

Targeted delivery of drugs in different parts of the human gastrointestinal (GI) tract is well studied and applied in the pharmaceutical industry. This chapter includes results from research undertaken to bring the technique of targeted delivery into the food area. In order to predict the fate of a food particle in the GI tract, some important factors must be considered. A good estimate of the transient flow field under the deforming walls of the stomach becomes critical. The mechanical forces generated by peristaltic flow, combined with biochemical reactions, facilitate size reduction of large food particles. Mixing and churning continues until the particles achieve a size less than 2 mm. Then the thick liquid (chyme) is slowly transferred into the duodenum through the pyloric valve. Physical and structural properties and caloric load of career food material become important parameters while predicting its disintegration.

Conducting in vivo experiments for this research in the human GI tract was not possible. Therefore, a three-dimensional mathematical model of the stomach was developed to study flow pattern, and disintegration of food particles. This model represents the shape and size of the human stomach and contraction waves along the walls with respect to time. FLUENT, a computational fluid dynamics (CFD) solver, was utilized to solve wall deformation, flow behavior, and size reduction of larger particles. Recent developments in magnetic resonance imaging (MRI) measurement techniques have allowed visualization of gastric motility. The model presented in this chapter is useful for studying the effects of peristaltic contractions along the walls of the stomach and hydrodynamics of food particles. Based on quantitative information of the flow field and the forces, size reduction of larger food particles was modeled.