A CFD model for investigating the dynamics of liquid gastric contents in human-stomach induced by gastric motility

摘要

The stomach is essential for food digestion, however, its operation is highly complicated while its mechanism is still not fully understood. Muscular movements of the stomach wall play critical roles in the human digestive process. They enhance the mixing of ingested foods with the gastric juice secreted from the stomach wall. A computational fluid dynamics (CFD) model is developed in this study to better understand the flow dynamics in the process of mixing liquid foods with the gastric juice. The gastric juice secretion is modeled as sources of mass and hydrogen ions continually added into the stomach lumen. Gastric emptying rates of different foods are determined according to their calorie content. The numerical results show that the terminal antral contraction (TAC) can considerably increase the kinetic energy in the stomach. The TAC creates retropulsive "jets" and reduces the pH of liquid gastric contents. The mixing efficiency of liquid gastric contents and gastric juice is low, which takes about 40-50 min to approach an acidic environment with a pH of 1.6 inside the stomach lumen. Our simulation results show that the density difference in food/stomach-juice has significant effects on the dynamic spatial distribution of gastric pH. The study shows that the developed model is a helpful tool for better understanding the digestion process in human-stomach.