NEW APPROACH IN MODELING PERISTALTIC TRANSPORT OF NON-NEWTONIAN FLUID

Transporting content in most biological systems is done through peristaltic transport phenomenon, examples of which include urine transport from kidney to bladder, swallowing of food through esophagus, the movement of chyme in small intestine, lymph transport in the lymphatic vessels, and in the vasomotion of small blood vessels such as arterioles. The present investigation simulated a transient peristaltic transport by developing a model based on fluid-solid interaction (FSI) method. The conduit in which peristaltic flow occurred was assumed to be axisymmetric. The propagating wave was simulated by prescribing a set of displacements, along the radial direction, on the wall. Both fluid and solid domains underwent large deformations as load applied. Due to large deformations, the adaptive discretization was considered. The ADINA 8.5 software, as finite element analytical software, was applied to study peristaltic transport. The results indicated that the present numerical method can properly introduce the features of the flow. The obtained results reveal that as amplitude ratio increases, axial velocity will increase, resulting in an increase in volume flux. Volume flux fluctuates through the passage of time in a cycle and along a wavelength. An increase in index of non-Newtonian fluid results in a decrease in velocity and increase in wall shear stress. It is observed that by increasing the amplitude of propagating wave, reflux will be increased; meanwhile, peristalsis works as a more efficient pumping process against the pressure applied as a boundary condition. The discussion on reflux according to its physiological importance seems to be helpful, thus the net displacement of the fluid particles after the transit of a single wave was calculated.