Peristaltic transport of a Casson fluid in a finite channel: Application to flows of concentrated fluids in oesophagus

Abstract

This model is targeted to study the swallowing of peristaltically driven food stuff such as jelly, tomato puree, soup, concentrated fruit juices and honey in the aboral direction confined to an oesophagus by modeling it as finite channel. Considering such highly concentrated fluids as Casson fluid in the fully stretched activated state, the dependence of pressure on space and time has been investigated for time averaged flow rate. Pressure distribution has been studied along the oesophageal length for an integral and also a non-integral number of waves at different time instants. Local wall shear stress and the role of yield stress have also been the areas of investigation. Mechanical efficiency of oesophageal pump during the Casson food transportation has been obtained. Reflux limit of perstaltically driven flow of Casson food bolus has also been discussed. The effect of Casson food bolus vis-à-vis Newtonian food bolus has been compared analytically, numerically and computationally from investigation point of view. It is observed that the pressure distribution is even and uneven respectively for the case of integral and non-integral number of waves. It is also concluded that it is not as easy to swallow Casson fluids (such as concentrated jelly, honey, soup, juice, etc.) as Newtonian fluids (such as water). As plug flow region widens, the pressure difference increases, indicating thereby that the averaged flow rate will be less for a Casson fluid. Physically, the oesophagus works more to swallow fluids with high concentration. It is also inferred that such fluids are more prone to reflux. © 2010 World Scientific Publishing Company.