Wavy falling film

Grimley (G10, Gil) used an ultramicroscope technique to determine the velocities of colloidal particles suspended in a falling film of tap water. It was assumed that the particles moved with the local liquid velocity, so that, by observing the velocities of particles at different distances from the wall, a complete velocity profile could be obtained. These results indicated that the velocity did not follow the semiparabolic pattern predicted by Eq. (11) instead, the maximum velocity occurred a short distance below the free surface, while nearer the wall the experimental results were lower than those given by Eq. (11). It was found, however, that the velocity profile approached the theoretical shape when surface-active material was added and the waves were damped out, and, in the light of later results, it seems probable that the discrepancies in the presence of wavy flow are due to the inclusion of the fluctuating wavy velocities near the free surface. 

Shkadov, V. Y., and Sisoev, G. M. (2000b). Wavy falling liquid films theory and computation instead of physical experiment. In Chang, H.-C., ed., lUTAM Symposium on Nonlinear Waves in Multi-Phase Flow, volume 57 of Fluid Mechanics and Its Applications, 1-10. Notre Dame, USA Notre Dame University. 

For simplifying the problem, the simulated object is the liquid-gas contacting falling film with wavy interface as shown in Fig. 8.51. The simulation is on the two-dimensional x-z plane. Xiao [12] established the model equation and give the simulated results as follows. 

Wasden, F. K., and A. E. Dukler, 1989, Insights into the Hydraulic of Free Falling Wavy Films, AIChE J. 35(2) 187-195. (3)... 

Wasden FK, Dukler AE. A numerical study of mass transfer in free-falling wavy films. AIChE 1990 36(9) 1379-1390. 

Mudawar, I., and Houpt, R. A. (1993) Measurement of Mass and Momentum Transport in Wavy-Laminar Falling Liquid Films, International Journal of Heat and Mass Transfer, Vol. 36(17), pp. 4151-4162. 

Yih SM, Chen KY (1982) Gas absorption into wavy and turbulent falling liquid films in a wetted-wall. Chem Eng Commiin 17(1-6) 123-136... 

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