Numerical simulation of aerodynamics of a standard fog collector

To-day, fog collection is an alternative, actively developed method of obtaining water, which involves both natural and industrial sources of humid air. A fog collection system is based on creating an obstacle to the flow of fog using mesh materials. Moving droplets of water collide with the mesh fibers, stick together and drain into the gutter. For the general characteristics of such systems, the efficiency of aerodynamic collection is the determinant factor. This article is aimed at gaining more fundamental knowledge about the aerodynamic behavior of water aerosols during fog collection. To this end, the authors have developed a computational model of aerodynamics of a standard fog collector, which combines scales differing by four orders of magnitude. Each fiber of the grid is considered separately with an accuracy of 0.1 mm. The collector contains a two-layer grid and is several meters long and wide. The dependences of aerodynamic collection efficiency on the shading coefficient have been obtained and their maximum values have been determined at the speed of the incoming flow of 3-7 m/s. It is shown how the efficiency value will change when the calculation uses the flow velocity before or after passing through the collector or the total pressure. The total pressure difference has precise limits and does not depend on the location of the measurement near the collector. The vector field of flow velocities in the reservoir is calculated, and the angle of incidence of the flow is analyzed across the entire surface of the grid. At a dimensionless distance between the mesh layers of 50 or more, the efficiency of aerodynamic collection remains constant, and the velocity vector is equally directed relative to the surface of the layers. In this case, the air flow is perpendicular to the second layer of the mesh in the center of the standard fog collector, and nearby its edge it maintains the angle of incidence on the first layer.