Wave behavior in horizontal annular air–water flow

Estimation of the radioactive aerosols capture in accidental sequences of nuclear power plants

“…Swanson [Schubring, 2008] found that the gas friction velocity was equal to the wave celerity for his databank. The gas friction velocity is defined as follows being  w the wall shear stress.…”

“…Hundreds of interfacial wave behavior studies have been carried out by different authors in both vertical and horizontal flows. All of them refer to the existence of two types of waves, the first one have small amplitudes compared with the liquid film thickness, move at low velocities, their lifetime is short, they usually do not occupy the whole tube circumference and do not appear to carry mass [Hewitt and Govan, 1990;Schubring, 2008;Alekseenko 2008Alekseenko & 2009. The second type of waves have a longer lifespan, their amplitudes are usually several times the liquid film thickness and carry mass along the tube [Hanratty and Hershman, 1961;Asali and Hanratty, 1993;Schubring, 2008;Alekseenko 2008Alekseenko & 2009.…”

“…All of them refer to the existence of two types of waves, the first one have small amplitudes compared with the liquid film thickness, move at low velocities, their lifetime is short, they usually do not occupy the whole tube circumference and do not appear to carry mass [Hewitt and Govan, 1990;Schubring, 2008;Alekseenko 2008Alekseenko & 2009. The second type of waves have a longer lifespan, their amplitudes are usually several times the liquid film thickness and carry mass along the tube [Hanratty and Hershman, 1961;Asali and Hanratty, 1993;Schubring, 2008;Alekseenko 2008Alekseenko & 2009. For vertical tubes, in the order of 6 cm or smaller, the liquid film is uniformly distributed around the tube circumference , and the disturbance waves appear circumferentially coherent [Hall-Taylor, 1963;Hewitt and Lovegrove, 1969;Asali and Hanratty, 1993] and symmetrical [Hewitt and Hall-Taylor, 1970;Ohba and Nagae, 1993].…”

Avaliação Da Pressão Dinâmica No Modelo De Dois Fluidos Unidimensional Aplicado Ao Escoamento Anular Vertical

“…De acordo com diversos autores (Paras & Karabelas, 1991;Schubring & Shedd, 2008;Farias et al, 2012;Zhao et al, 2013;Berna et al, 2014)é assumido que dois tipos de ondas podem existir na superfície do filme de líquido: as de grande amplitude ou disturbance waves e as de baixas amplitudes ou ripples. Sekoguchi & Takeishi (1989) apresentaram imagens de ondas de grande amplitude, enfatizando que para o escoamento vertical ascendente, suas características se distribuem uniformemente ao longo da circunferência do duto.…”

“…Belt et al (2010), por outro lado, argumentam que a rugosidade efetiva da interface líquido-gás pode ser considerada proporcionalà altura da onda, e que não há evidência física para a incorporação do Reynolds do gás na expressão. Schubring & Shedd (2008) realizaram experimentos para medir a velocidade e frequência das ondas e determinaram que as ondas de grande amplitude se movimentam numa velocidade maior do que a superfície do líquido, com uma frequência menor, enquanto que as ondas menores se movimentam com menor velocidade, com baixas amplitudes e maior frequência. Devidoà forte turbulência do gás, as ondas de baixa amplitude encontram-se sempre presentes na superfície do filme.…”