*4.1. Pressure Rising*

The flow of biological fluid in peristaltic motion circulating in the human body are investigated in Figures 2–5. The pressure rise was defined as <sup>Δ</sup>*<sup>P</sup>* = <sup>+</sup> <sup>1</sup> <sup>0</sup> *dx*. In Figure 2, it can be seen that by increasing the value of the Eotvos number, the pumping rate rose in the co-pumping region (**Δ***p*<0**,** *Q*>0), whereas the opposite behavior was seen in the retrograde pumping region (**Δ***p*>0**,** *Q*<0), (**Δ***p*<0**,** *Q*<0) and the free pumping region. From Figure <sup>3</sup> it is noticeable that the pumping rate dropped (**Δ***p*<0**,** *Q*>0) in the co-pumping region when we increased the value of the added mass coefficient and the free pumping region (**Δ***p*<0**,** *Q*<0). In the retrograde pumping region (**Δ***p*>0**,** *Q*<0) the opposite behavior was noted. It can be seen in Figure 4, that when we increased the value of Reynolds' number Rbe, the pumping rate rose in the co-pumping region (**Δ***p*-<sup>0</sup>**,** *Q*0). However, the behavior was the opposite in the retrograde pumping region (**Δ***p*>0**,** *Q*<0) and in the free pumping region (**Δ***p*<0**,** *Q*<0). From Figure 5, it is noticeable that there was an upsurge in the pumping rate (**Δ***p*<0**,** *Q*>0) in the co-pumping region by increasing values of slip velocity and free pumping region (**Δ***p*<0**,** *Q*<0). In the retrograde pumping region (**Δ***p*>0**,** *Q*<0) the behavior was quite the opposite.
