The effect of porosity in a row of barriers on mitigation of flow dynamics and barrier interaction: Flood water in a flume

This study investigates the unsteady hydrodynamic behavior of water interacting with a single horizontal row of barriers in an idealized channel, considering barrier porosity (0.3≤ϕ≤1) and channel slope (0°≤θ≤45°). Using computational fluid dynamics (CFD), fluid–structure interactions are simulated under extreme conditions representative of floods and tsunamis, enabling assessment of barrier performance in mitigating flow impact. The numerical framework captures the evolution of the water interface and flow redirection as the fluid navigates barriers of varying porosity and slope. Pressure and shear forces acting on both the barriers and downstream wall are quantified, and a bivariate polynomial correlation is developed to express these forces continuously as functions of ϕ and θ, facilitating interpolation across the parameter space. Results indicate that increasing porosity generally amplifies both pressure and shear forces, with the most significant pressure jumps occurring between ϕ=0.3–0.4 and ϕ=0.9–1. Pressure forces consistently exceed shear forces. Increasing the slope from 0° to 45° raises pressure forces by nearly fivefold and shear forces by roughly threefold, while flood front run-up and arrival time remain largely unaffected. Furthermore, adding more barriers, particularly at lower porosities, steadily increases the forces experienced. These findings reveal the non-linear interplay between porosity, slope, and barrier arrangement on hydrodynamic loads, providing critical guidance for designing and optimizing barriers in flood mitigation and coastal protection applications.