Biofluid dynamics of digestion in the stomach: Insights from computational modeling*

The stomach is responsible for mixing, grinding, sieving, and chemically breaking down food. The peristaltic motion of the stomach walls combines with the secreted gastric enzymes to physically and chemically breakdown the ingested food. However, experimental investigation of these phenomenon is very challenging and cost intensive. In this study, we present a computational model of the stomach to simulate the digestion of a meal with solid and liquid components. The enzyme pepsin is secreted from the stomach walls and acts on the dissolved protein. The solid food particles move and dissolve under the action of the surrounding fluid motion, gravity, and drag forces. The mixing of the contents, the hydrolysis of the meal, and the emptying from the stomach are quantified for a healthy stomach, as well as for conditions with reduced stomach motility. The findings demonstrate the potential of computational approach in this field. They generate new insights into gastric digestion and show its effect under variations in wall motion caused by disease and dysfunction.