CFD modeling of mudflow impact on rigid barriers using the Herschel–Bulkley rheology

Abstract

This study employs a Computational Fluid Dynamics (CFD) approach to simulate the dynamics of nonNewtonian mud/debris flows impacting rigid barriers under flume-scale conditions. The flow is modeled using the Herschel–Bulkley rheology to capture both yield stress and shear-thinning behavior characteristics of mud materials. Numerical simulations are performed with OpenFOAM for 12 configurations varying in slope inclination (0◦ –15◦) and barrier position relative to the slope toe. The model is first validated against experimental data, showing good agreement in terms of pressure evolution and velocity profiles. The numerical results reveal that flow behavior is strongly governed by the interplay between gravitational acceleration, yield stress effects, and energy dissipation within the basal shear layer. Increasing the slope angle enhances the conversion of potential to kinetic energy, leading to higher impact velocities, larger runup heights, and greater impact forces. Conversely, increasing the distance between the slope toe and the barrier promotes viscous dissipation, thereby reducing the available impact energy. Notably, for the steepest slope (15◦), the effect of barrier distance becomes minor due to compensation between acceleration and front spreading. These findings provide new insights into energy conversion mechanisms and their implications for the design and placement of protective barriers in mud/debris flow prone areas.