Particle Trajectory in a Bidirectional Vortex Flow

Abstract

In this research particle trajectory in a bidirectional vortex flow has been numerically predicted and the results experimentally validated. Scale analyses of forces show their order of magnitudes and give a criterion to recognize the order of magnitude of exerting forces on the particle. The particle has been assumed to be a rigid sphere. Initial velocity, diameter, density, and position of entering particle are assumed to be known. If the particle length scale is considered not to be comparable with the chamber length and if particle number density is low, then influence of particle on the flow field is negligible and a one-way solution is applicable. The governing equation is converted to a set of nonlinear, coupled, second-order ODE and solved by a numerical scheme. Results show that higher density, larger diameter, and higher initial axial velocity tend to move the particles further in the axial direction. Also, the maximum axial movement of the particle occurs when the initial radial velocity is zero and there is an optimum entrance position that provides a maximum traveling trajectory for particles. Increasing initial z-direction velocity component and density will result in increasing traveling trajectory.

Droplet size and velocity distributions of wave-impact sea spray over a marine vessel

“…where is mass of the droplet, is time, is droplet velocity, is air velocity, is water density, ∀ is droplet volume, is gravity, is drag coefficient, is droplet diameter, is air density, and is added mass force coefficient. The coefficient is assumed to be 0.5 and can be calculated as follows (Dehghani et al 2009):…”

“…When a spray cloud moves, droplets start their movements at their initial positions and finish by impinging on vessel surfaces (Dehghani et al, 2009;Zakrzewski and Lozowski, 1988). The droplet trajectory method, which needs the initial size and velocity distributions, will determine the distribution of the size and velocity of the droplets at every section of the spray cloud, and consequently, the final distribution of the spray flux over the vessel surfaces (Dehghani et al, 2013;Dehghani et al, 2016a).…”