Simulation of fluid mixing in the small intestine

Abstract

There are many gastrointestinal diseases, such as Crohn’s disease, which can be treated effectively with topical, localized medicine delivered to the intestinal wall through the gastrointestinal tract by the use of a targeted drug delivery capsule. The success of such a delivery method is contingent on the properties of the fluid flow near the delivery site; specifically, how well-mixed the medicine will be in the chyme so that it can act on the intestinal wall. Pursuant to understanding the mixed state of the chyme, several fluid simulations were performed with ANSYS Fluent, simulating different types of muscular contractions. Fluid particles – which were originally segregated into three sections of the simulated small intestine – were tracked, and simulation results were compared based on how well-distributed the tracked particles were at the end state, using the second moment of distribution. The results of this comparison have revealed that there is little difference between the mixing produced by segmentation in a 3.0 cm diameter small intestine and that produced in a 2.0 cm diameter small intestine. Results have also shown little difference between mixing produced when the segmentation contractions vary qualitatively in any of several ways. There is, however, some difference between distribution produced by segmentation contractions and peristaltic, or propulsive, contractions. This work could be further pursued with more simulations; of different types of contractions, of contraction patterns with different properties, and with simulations with more comprehensive particle tracking. It would also be straightforward to incorporate analysis of the large intestine into the study.