Water-Energy Nexus (Jan 2022)
Numerical simulations of lateral input effect in an open channel to reduce disturbances in the mainstream channel using CFD
Abstract
Today, open channel structure is widely used in agricultural irrigation systems, fish breeding ponds, water purification or transfer systems, and streams. The biggest challenge when designing an open channel is to determine the overall shape of the channel and the connections and proper placement of the inlets and outlets so that the least turbulence and eddies are created in the channel in order to avoid issues such as increasing channel erosion, pressure on the walls, the creation of sludge and sewage due to stagnation of water in the canal, the reduction of water quality, the increase of polluting particles in the water, or even the breakage and deformation of the canal. In addition, parameters such as temperature, particle concentration, pressure, water level, etc. can be controlled inside the channel and are uniform along the channel path. The longer the channel and the more bends it has, the more difficult it is to place the branches. In this research, the uniform flow of fluid inside a channel with a 90° bend has been simulated, and its effective factors have also been studied. By adding lateral branches such to be widely used in various industries, it was proved that could be reduced, the circulation and disturbances generated by inflow by editing the shape of inlets and branches. The effects of circulation reduction on water flow after the bend were assessed and simulated. The flow simulation inside the channel was calculated with computational fluid dynamics; needless to mention that the channel flow had been assumed to be incompressible unsteady, and two-phase. Moreover, the flow was simulated based on the Naiver-Stokes equation and Re Normalization Group (RNG) model. The results showed that increasing the number of system inlets (meantime keeping the inflow and velocity of the inlet fluid constant) and the proper arrangement of each inlet greatly reduces the amount of turbulence in the flow at the inlet; in this case, the water flow gets uniform in a shorter path, and time period; as a result, the effects of sub-branches on the main channel would be negligible.
