A novel dynamic contact angle model of lattice Boltzmann method for water droplet impact on proton exchange membrane fuel cell channel surface

Abstract

To predict water behavior accurately and explore water droplet impact on a proton exchange membrane fuel cell channel surface, a novel dynamic contact angle model was introduced. A two-dimensional model of water droplet impact was established via the lattice Boltzmann method, and it was validated.Influences of equilibrium contact angle, sliding angle, lateral velocity, and longitudinal velocity were all explored. The results reveal that when droplet impact the channel surface, it appears in three states: spreading, rebounding, and moving. The model can capture the water-air interface accurately. When the droplet impacts a hydrophobic wall, the droplet jumps up after rebounding, and eventually returns to its original shape. When the equilibrium contact angle increases, the spread factor gradually decreases, and the droplet keeps moving on the wall. With the increase of sliding angle, the spread factor gradually decreases, and the height of the droplet rebound also increases. The lateral velocity can cause the front end of the droplet to be elongated. As longitudinal velocity increases, spread factor increases, and relative distance gradually decreases. Novelty Statement• A novel dynamic contact angle model is introduced.• A two-dimensional model of water droplet impact is established.• Influences of equilibrium contact angle, sliding angle, and velocity are explored.• The model can capture the water-air interface accurately.channel, dynamic contact angle model, lattice Boltzmann method, proton exchange membrane fuel cell, water droplet impact | INTRODUCTIONWater management in proton exchange membrane fuel cell (PEMFC) is crucial to the performance and lifetime of a PEMFC. 1,2 For example, if water is accumulated in PEMFC, leading to flooding, gas cannot enter PEMFC. If there are less water in it, its performance deteriorates. 3,4 It is therefore important to predict water behavior in PEMFC. 5,6 Much research on the simulation of water behavior has already been carried out. Li et al 7 explored droplet behavior