Article
Computer Science, Interdisciplinary Applications
Mohammad Nikooei, Clarence Edward Choi
Summary: This study proposes a new approach to model the effects of deposition in flow-type landslides. By simulating the flow-normal accelerations during the deposition process, a deposition model that considers the initial aspect ratio and slope angle of the debris is developed and implemented into engineering simulations. The new model improves predictions of flow distance and duration, and overcomes limitations of traditional models. This research is important for improving the delineation of flow-type landslides in mountainous regions.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Andrea Pasqua, Alessandro Leonardi, Marina Pirulli
Summary: Continuum-based numerical models, including depth-averaged (DA) models and three-dimensional (3D) models, are widely used to simulate debris flows and predict key parameters for designing mitigation structures. This study aims to couple a DA model and a 3D model (DA-3D) to analyze flow-structure interaction. The transition from one model to the other requires the outputs of the DA model to become inputs of the 3D model. The successful coupling of the two models is validated through numerical simulations and experimental results.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Mechanics
Mohamed Arif Mohamed, David Wood, Bing Feng Ng
Summary: In this study, an activated curvature production term was considered to describe turbulent flow over two-dimensional hills. The new term, referred to as the SR modification, depends on the difference between strain rate and rotation. It was compared to different turbulence models, and the Kato-Launder model showed the best overall predictions for various flow properties. The SR model was slightly less accurate but uniquely predicted flow separation and re-attachment in specific locations.
Article
Mechanics
A. Ahmadi, I Karimfazli
Summary: The study assesses the impact of viscosity regularization in predicting transient flows of viscoplastic fluids. It finds that common methods of evaluating solution errors can overestimate the accuracy of viscosity regularization results, especially when flow conditions approach the motionless state. The accuracy of bi-viscosity regularization in predicting unyielded regions is also quantified, disproving the convergence of numerical estimates using yield stress contours.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2021)
Article
Mathematics, Applied
E. D. Fernandez-Nieto, J. Garres-Diaz, P. Vigneaux
Summary: Starting from the Navier-Stokes equation, we derive two shallow water multilayer models for yield stress fluids, taking into account normal stress contributions. A specific numerical scheme is designed to accurately solve the transitions between yielded and unyielded (or pseudoplug) zones. Numerical simulations agree well with physical experiments, allowing for a comparative study with other shallow water and lubrication models.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2023)
Article
Geochemistry & Geophysics
Gabriele Lanzafame, Pier Paolo Giacomoni, Federico Casetta, Lucia Mancini, Gianluca Iezzi, Massimo Coltorti, Carmelo Ferlito
Summary: Understanding lava flow dynamics during major effusive events is crucial in volcanic areas with a high risk of lava invasion. This study investigates the 1669 eruption of Mount Etna volcano and reconstructs the degassing, crystallization, and rheological history of the magma and lavas. The results indicate that a combination of factors, including lava tunneling, delayed crystal nucleation and growth, and the presence of deformed bubbles, maintained the high fluidity of the melt suspension, allowing the flow to reach considerable distances from the vent. Accurate real-time petrological characterization is essential for reliable viscosity modeling and predicting lava flow direction.
JOURNAL OF PETROLOGY
(2022)
Article
Computer Science, Interdisciplinary Applications
Clarence Edward Choi, Mohammad Nikooei
Summary: Ploughing is a mechanism where a geophysical flow pushes sediments along its path, increasing its flow length. However, the physics of ploughing has been missing in hazard assessment tools due to the difficulties of simulating the competing effects of erosion and deposition. In this study, 2D non-depth-averaged (non-DA) simulations are used to understand the physics of ploughing, and a closure model is developed and implemented into a depth-averaged (DA) framework for practical simulations.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Engineering, Mechanical
Bojie Hong, Changli Hu, Haojie Xing
Summary: The objective of this study is to propose a modified method for the cavitation model and turbulence model, accounting for the influence of vortex motion on unsteady cavitating flows. A function of the ratio of strain rate tensor and rotation rate tensor is introduced into the Zwart cavitation model and the SST gamma-Re-theta t turbulence model respectively. The modified method is applied to simulate the unsteady cloud cavitating flow around Clark-Y hydrofoil and evaluated by the experimental data. The results show that the modified model can better capture the unsteady process of the cloud cavity, especially the fully developed attached cavity and the large-scale cloud shedding behaviors. These benefit from the increase of turbulent dissipation rate per unit energy and the evaporation rate of the modified method. In addition, the lift coefficient fluctuation in time and the time-averaged u-velocity profiles predicted by the modified model are better agreement with the experimental results.
ACTA MECHANICA SINICA
(2023)
Article
Thermodynamics
Pierre-Alexandre Masset, Florent Duchaine, Antoine Pestre, Laurent Selle
Summary: This study uses 3D Pore-Level Direct Numerical Simulations to investigate the combustion process in porous burners, comparing the results with a 1D volume-averaged model and discussing the discrepancies in burning rate, profiles, and reaction rates. It is found that preheating, wrinkling, and wall quenching are the main factors driving the global burning rate. Additionally, a new closure for reaction rates based on flamelet assumption is proposed, which eliminates the unwanted effect of hydrodynamic dispersion on burning rate.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Woochan Seok, Sang Bong Lee, Shin Hyung Rhee
Summary: In this study, modified formulations of the PANS model were suggested to accurately predict secondary flow by resolving the anisotropy of turbulence. The modified mPANS models showed improved predictions of secondary vortex and streamwise velocity component compared to the original PANS results by decreasing the modeled turbulent kinetic energy, demonstrating the effectiveness of the modifications.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
H. Rahmani, S. M. Taghavi
Summary: Via numerical computations, we study the behavior of a viscoplastic fluid in plane Poiseuille flow with a superhydrophobic groovy lower wall. We focus on the thin channel limit and use the Bingham model to quantify the viscoplastic rheological behavior. The effects of various parameters on flow velocity fields, unyielded plug zones, effective slip lengths, and friction factors are analyzed.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2023)
Article
Engineering, Aerospace
Gustavo Luiz Olichevis Halila, Anil Yildirim, Charles A. Mader, Krzysztof J. Fidkowski, Joaquim R. R. A. Martins
Summary: Inclusion of transition to turbulence effects in computational fluid dynamics simulations can enhance accuracy but may lead to convergence difficulties.
Article
Mechanics
Hani Nami Alahmadi, Shailesh Naire
Summary: This study theoretically investigates the draining and thinning of vertically aligned thick liquid films. It focuses on the influence of non-Newtonian and viscoplastic effects on the process and reveals that the film's properties have a stronger impact on the thinning rate compared to gravity.
Article
Engineering, Chemical
Hongmei Lyu, Dirk Lucas, Roland Rzehak, Fabian Schlegel
Summary: This study focuses on the limitations of the standard Euler-Euler model when the bubble diameter exceeds the size of a computational cell, and proposes a particle-center-averaging method to address the inconsistency. The results demonstrate that the particle-center-averaging method can restore the consistency of bubble forces and provide mesh-independent solutions, making it suitable for bubbly flow simulation.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Geosciences, Multidisciplinary
W. Sun, X. Meng, Y. Wang, S. S. Hsiau, Z. You
Summary: This paper presents a depth-averaged theory for studying submarine landslides and related water waves. The theory considers both a pure fluid regime and a mixture regime of grains and fluid, separated by an interface. The established theory consists of five coupled conservation equations, which accurately describe the behavior of particles in underwater collapse experiments and the profiles of free-surface waves. The computed results are in good agreement with previous experimental findings.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)