Modeling droplet collision dynamic for Lagrangian simulation of impinging spray under high ambient pressures using an improved approach

Spray-to-spray impingement under ambient pressures of 10–60 atm was investigated numerically and experimentally, with particular interest in illustrating the influence of droplet collision dynamic on the spray characteristic. Specially, an improved approach for collision probability prediction was proposed by taking into account the initial size and distance of colliding droplets. The numerical simulations show our approach accounts for the collisions among droplets located in the different computational cells, hence producing substantial independence of computational cell size and total parcel number. The improved approach was subsequently implemented with a recently proposed pressure-dependent collision outcome model to simulate the impinging spray characteristics, the results were compared to the widely-used O'Rourke’s and Estrade et al.’s models. By implementing the improved approach with the pressure-dependent collision outcome model, our numerical simulations successfully reproduce the tendency that droplet bouncing is promoted with increasing ambient pressure, which has been fully recognized in the previous experimental and theoretical studies, however, rarely reflected in previous numerical works. Spray microcosmic characteristic was further discussed based on the numerical simulations.