Un innovativo modello multistrato a concentrazione variabile per le valanghe granulari

Articolo selezionato come Featured e Scilight Article da parte dell'American Institute of Physics

Articolo selezionato come Featured e Scilight Article da parte dell'American Institute of Physics

L'articolo, "A well-posed multilayer model for granular avalanches: Comparisons with laboratory experiments", recentemente pubblicato su Physics of Fluids è stato selezionato come Featured e Scilight Article da parte dell'American Institute of Physics a riconoscimento dell’elevato impatto scientifico. Lo studio, svoltosi nell'ambito del progetto Marie Curie "StratifiedGRANULAR" del dott. Luca Sarno (attualmente ricercatore presso il DICIV), è stato condotto presso la Chair of Fluid Dynamics della TU Darmstadt (Germania). In particolare il lavoro ha riguardato lo sviluppo di un modello multistrato a concentrazione solida variabile per descrivere la dinamica delle valanghe granulari in modo computazionalmente efficiente e numericamente stabile. Il modello è stato validato su un ampio spettro di esperimenti, in parte condotti presso il Laboratorio di Idraulica Ambientale e Marittima del DICIV e presso il Dept. of Hydraulic and Ocean Engineering della NCKU (Taiwan).

L'articolo è disponibile al seguente link: https://doi.org/10.1063/5.0106908.

Il testo dell’articolo divulgativo apparso su AIP Scilight (https://doi.org/10.1063/10.0014866) è riportato di seguito:

"Avalanches and debris flows are typically modeled as flow processes in granular media. Sarno et al. proposed a mathematically well-posed multilayer model for these complex systems and compared computational results from this model to several laboratory experiments.

The model describes the evolution of granular avalanches in a computationally efficient way by using a multilayer approach. The flow domain is discretized into several miscible layers evolving according to a specified rheology. The model also incorporates a dilatancy law to consider the dynamical effects of variable volume fraction.

“This is the latest in a series of contributions about granular flows in the framework of the Marie-Curie project ‘Stratified Granular,’” said author Luca Sarno. “The main goal of the current work is to assess the ability of the proposed multilayer model to practically describe a variety of granular flows.”

Frictional effects of the sidewalls were also included, allowing the investigators to compare computational results from their model to three different experimental scenarios. Specifically, the model results compared favorably with the velocity measurements of unsteady surface flows, dam-break flows in an inclined narrow flume, and steady flows over an erodible bed. In this third investigation, volume fraction measurements were also obtained using a stochastic-optical method and compared to simulations by the model.

“Comparison with various laboratory experiments encompassing different geometries and flow conditions showed that the proposed multilayer model is a reliable and computationally cost-effective tool for practically describing granular flows,” Sarno said.

The authors also suggested that the proposed model is a good alternative to fully three-dimensional models with similar rheologies, especially considering that its mathematical properties ensure the convergence of numerical simulations."

Pubblicato il 21 Novembre 2022