Fluid flow and mass transfer characteristics of water and polyacrylamide solution

The type of fluid, the shape of wavy-walled tube, and the flow field have important impacts on mass transfer. Pressure difference, mass transfer rate, and flow visualization experiments were carried out in wavy-walled tubes of different shapes with purified water and polyacrylamide (PAM) solution for both steady and pulsatile flow. Based on the experimental results, it was found that the effect of mass transfer is enhanced with increasing amplitude of wavy-walled tubes at the same net Reynolds number and that fluid mixing with PAM solution is better than that with water extract for both steady and pulsatile flow. Stable and unstable flow pattern states were found in the wavy-walled tube during a single oscillation cycle. Mass transfer rate and fluid mixing under pulsing flow conditions were better than those under steady flow conditions at the same net Reynolds number, which means that mass transfer was enhanced significantly under pulsatile flow.

Graphical abstractBased on the experimental results, it is found that the effect of mass transfer enhances for increasing the amplitude of wavy-walled tubes at the same net Reynolds number extract for steady and pulsatile flow.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Behaviors of water and PAM aqueous solution are studied in the wavy-walled tubes. ► Fluid mixing and mass transfer rate are enhanced with increasing the tube amplitude. ► PAM aqueous solution can reduce the frictional resistance compared with the water. ► Mass transfer rate is greatly increased for pulsatile flow over steady flow.