Investigation of eddy diffusivity and heat transfer coefficient for free-falling turbulent liquid films subjected to sensible heating

Computational modeling of turbulent evaporating falling films

“…After a steady film is formed, it is observed that a 0.2-s period is sufficient to provide repeatable heat transfer values as explained in a recent study by Mascarenhas and Mudawar [22] involving turbulent falling films subjected to sensible heating. Fig.…”

“…8 compares the average eddy diffusivity profile across the film at an axial location of x = 0.75 m from the inlet of the heated length determined from the computational model with the Mudawar and El-Masri profile for three different cases. The average profile is obtained by averaging eddy diffusivity profiles for different subintervals within a period of a single dominant wave, as explained by Mascarenhas and Mudawar [22] for turbulent falling films subjected to sensible heating. Notice that, like the empirical profile, the computed eddy diffusivity is zero both at the wall and the film interface.…”

Experimental and computational investigation of interfacial shear along a wavy two-phase interface

“…7 shows the time-averaged eddy diffusivity profiles across the water layer for different Re l and Re g values. Notice that the turbulence is completely suppressed at the interface because of surface tension effects as suggested in [1], and the eddy diffusivity profile has a broader span and different slope near the interface as compared to falling films [2]. It is also seen that, for most of the cases considered, peak eddy diffusivity is nearly constant, but the eddy diffusivity profiles are more distinct at high y + values.…”

“…However, these models are further complicated by interfacial traits that are not easily predicted. The interfacial wave structure and interfacial dampening of turbulent eddies have been the focus of considerable study [1][2][3]. These, in turn, influence interfacial velocity and temperature gradient, key ingredients in the development of relations for interfacial mass transfer, shear and heat flux found in theoretical two-phase flow models.…”

Flow Characteristics of the Vertical Turbulent Falling Film at High Reynolds Numbers

“…Generally, the mean thickness data of falling films obviously deviate from the Nusselt relation when Re l ≥ 400 . In the actual application, a high Re l is usually required to achieve a high heat transfer coefficient . However, a few studies has been carried on turbulent falling liquid films, and even the flow behavior of turbulent falling films is rarely investigated due to the limitation of previous measurement methods.…”