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. 2020 Jun 22;10:10102. doi: 10.1038/s41598-020-66887-w

Figure 1.

Figure 1

Mechanism of forward transport (pumping) driven by peristalsis in fluids and solids. (a) The movement of fluid (the dots represent fluid particles) driven by peristaltic compression of the walls of a 2D tube. The fluid movement in this figure is calculated using the Navier-Stokes equation with zero traction (pressure) at the two ends of the tube. (b) The pressure field in the tube in the deformed state. The fluid is displaced by the moving walls and this creates high pressure at the neck of wall movement. The pressure difference is same for retrograde and anterograde flow. However, the resistance is large posterior to the site of contraction. Compared to anterograde flow, retrograde flow needs the fluid to flow through a narrower tube. This results in a greater anterograde flow (magenta dots in a) compared to retrograde flow (green dots in a). (c) The movement of a solid bolus (yellow ellipse) driven by peristaltic motion of the walls of a 2D tube. The contact forces between the moving walls and the solid bolus are responsible for forward transport. The position of the solid bolus with respect to the dotted lines shows that the solid is moved forward. (a) was generated with MATLAB 2019b(https://www.mathworks.com/products/matlab.html). (b) was generated with COMSOL Multiphysics 5.4 (http://comsol.com). (c) was drawn in Adobe Illustrator 23.0(https://www.adobe.com/products/illustrator.html).