NUMERICAL STUDY ON MIXING AND PUMPING FUNCTIONS GENERATED BY PERISTALSIS IN A ZEBRAFISH INTESTINE
Jinyou Yang, Yuji Shimogonya, Takuji Ishikawa
Tohoku University, Japan
The intestine of zebrafish has been intensively used for investigating various biological phenomena, such as microbial flora, due to its transparency. Despite its biological importance, transport phenomena in the intestine of zebrafish have not been fully clarified. In this study, therefore, a numerical model was developed to explore transport phenomena caused by the peristaltic motion in a larval zebrafish intestine. Geometric data of the larval zebrafish intestine were extracted from Field et al. (2009) at different time after feeding. A model equation to describe contraction over long time was developed from the geometric data. By concurrently calculating the flow field generated by peristaltic motion and long time motion with the software CFX, the mixing and pumping functions were discussed. The results illustrated that the retrograde peristaltic motion mainly contributed to the mixing function of chyme, and that peristaltic mixing became larger than the Brownian mixing when spreading particle was sufficiently large. The anterograde peristaltic motion, on the other hand, mainly contributed to the pumping function. Pressure decrease inside the intestine was generated by the anterograde peristaltic motion, which may reduce the maintenance energy of muscle to propel the chyme in the intestine. These new findings provide better understanding of mixing and pumping functions in the zebrafish intestine.