Computational Models of the Fluid Mechanics of the Stomach

In the last 2 decades, the interest in developing computational fluid dynamics (CFD) models of the stomach has grown steadily. This bean-shaped organ plays a key role in our digestive system by chemically and physically processing food before emptying it into the intestines. The stomach walls drive the flow of the contents to achieve mixing, grinding, and emptying of the contents. Most computational models prescribe the motion of the walls and solve for the flow field inside the lumen, but some recent models also incorporate fluid–structure interaction between the muscles and the contents. Some models employ a simplified two-dimensional or axisymmetric geometry, while others use anatomically realistic stomach shapes. The emptying mechanism employed by the model and the inclusion, or lack thereof, of the pylorus further add to the nonconformity among the different models. In this review, we summarise these different CFD models of the stomach available in the literature. A comparison between these models with regard to their complexity, validation, and specificity is presented. While there has been rapid progress in the past few years, computational models are still far behind their other physiological counterparts, such as cardiovascular flows.