SPH-Based Numerical Study of the Impact of Mudflows on Obstacles

Abstract

In this work, we study the impact of a transient free-surface flow of viscoplastic fluid on a rigid obstacle. This study is conducted numerically using the SPH (Smoothed Particle Hydrodynamics) method, and the Herschel-Bulkley rheological model. The SPH code and its specific adaptations to our needs are presented. The capacity of the code to meet the requirements of our objectives is validated on classic benchmarks. The virtual experiment setup is presented. The local characteristics of the flow near the obstacle, the length of the dead-zone of fluid at rest which forms upstream of the obstacle and the shape of the pressure signal applied to the obstacle are analyzed with reference to the inclination angle and Froude number of the incident flow. This analysis highlights the existence of two impact regimes referred to as the dead-zone and jet impact regimes respectively with a transition occurring for values of the Froude number about 1.3 to 1.5. These values are coherent with previous experimental studies.

Numerical investigation on the role of check dams with bottom outlets in debris flow mobility by 2D SPH

“…The Herschel-Bulkley model has been widely used to describe the flow behavior of viscous debris flows [16][17][18] . In the Herschel-Bulkley model, the norm of deviatoric viscous stress tensor τ can be expresses as: where τ y is the yield stress, K is the consistency index, N is the power law exponent, and γ = (2S : S) 1/2 is the second invariant of the rate-of-strain tensor.…”

Towards debris flows simulation using SPH : Internal behaviour of viscous flows and mixtures

“…Albaba et al, 2015;Poudyal et al, 2019, among others) and the latter focusing on internal dynamics within the flow (e.g. Laigle & Labbe, 2017;Leonardi et al, 2014, among others). Due to their destructive nature, it is not possible to measure directly within the flow, and experimental small-scale facilities cannot fully understand how debris flow propagate and maintain their dynamics, due to scale effects.…”

“…The rheology of the models can be fitted to observation to recover macroscopic features of the flow. Time-independent rheological constitutive models have proven to be effective to model debris flows when the volumetric fractions of silts and clay is sufficient and local discontinuities, segregation and concentration heterogeneity can be neglected (Ancey, 2003;Laigle & Labbe, 2017). As a first approximation, muddy debrisflows can be studied at the macroscopic scale by considering a homogenous flow of a Newtonian viscous fluid (Han et al, 2014) or of a more complex material such as a Herschel-Bulkley fluid (Coussot & Meunier, 1996;Chambon et al, 2011).…”

Pressure evaluation during dam break using weakly compressible SPH

“…Some works presenting numerical solution of freesurface flows using SPH have also been published. These which dealt with dynamics of the flow are for example Colagrossi and Landrini [6], Ferrari et al [7], and Laigle and Labbe [8]. All these authors compared their results with experimental data published by Zhou et al [9].…”