Numerical simulation on flow characteristics of falling film outside the horizontal tube in low counter-current air flow

In this paper, the VOF (volume of fluid) method was used to simulate the thickness and velocity of the falling film in water-air interface at low counter-current air velocity outside the elliptical tube. The elliptical tube had a long semi-axis of 26mm and a short semi-axis of 13mm. The velocity of the air was 0.1 m/s. The Reynolds (Re) number was chosen as the influence factor and the Re numbers were 90, 225, and 311.7, respectively. The three dimensional simulated results showed that the film thickness and the film velocity increased with the increasing of the Re number. The film increased along the axis direction, and the differences of the film thickness in different axis distance increased with the increasing of the Re number.