arXiv subjects

P. -Y. Lagrée

Publications and source records attributed to P. -Y. Lagrée.

4 recordsLinked to original sources

arXiv2026

Comparing non-local granular fluid continuum models for silo discharge: Toward clogging prediction

Non-local constitutive theories have received increasing attention in continuum descriptions of granular flows. However, these models have not been systematically compared for silo discharge within a unified numerical framework. We address this gap with two-dimensional finite-volume method (FVM) simulations of silo discharge using the Basilisk platform. We first validate our FVM implementation of the dynamic non-local granular fluidity (NGF) model against the material point method results of Dunatunga & Kamrin (J. Fluid Mech., 2022, 940, A14), obtaining quantitative agreement. Second, we relate the discharge rate $Q$ to the outlet-to-particle size ratio $D/d$ and the non-local amplitude $A$. From the simulated $Q$, we then evaluate the clogging probability $J(D/d, A)$ within the probabilistic framework of Janda et al. (Europhys. Lett. 84 (4), 44002). The predicted $J$ decays exponentially with $D/d$, consistent with the experimental trend of Janda et al. (Europhys. Lett. 84 (4), 44002). Rather than directly predicting flow arrest, our approach captures the continuous probabilistic transition. Finally, within the same numerical framework and using identical values of $A$, we compare several non-local constitutive models, including several linearised variants that we derive. Almost all models predict a reduction in the discharge rate with increasing $A$, yet significant quantitative differences are observed among the models. The results are further classified into groups according to their predicted flow behaviour, revealing close correspondences among certain formulations. Notably, using the non-local amplitudes reported in the literature [Bouzid et al. (Phys. Rev. Lett. 111, 238301), Henann & Kamrin (Proc. Natl Acad. Sci. USA 110(17))] yields near-zero discharge rates. Ill-posed issues are discussed. The implementation of all models is open-sourced and computationally efficient.

cond-mat.soft↗

arXiv2017

Low-Shapiro hydrostatic reconstruction technique for blood flow simulation in large arteries with varying geometrical and mechanical properties

The purpose of this work is to construct a simple, efficient and accurate well-balanced numerical scheme for one-dimensional (1D) blood flow in large arteries with varying geometrical and mechanical properties. As the steady states at rest are not relevant for blood flow, we construct two well-balanced hydrostatic reconstruction techniques designed to preserve low-Shapiro number steady states that may occur in large network simulations. The Shapiro number S h = u/c is the equivalent of the Froude number for shallow water equations and the Mach number for compressible Euler equations. The first is the low-Shapiro hydrostatic reconstruction (HR-LS), which is a simple and efficient method, inspired from the hydrostatic reconstruction technique (HR). The second is the subsonic hydrostatic reconstruction (HR-S), adapted here to blood flow and designed to exactly preserve all subcritical steady states. We systematically compare HR, HR-LS and HR-S in a series of single artery and arterial network numerical tests designed to evaluate their well-balanced and wave-capturing properties. The results indicate that HR is not adapted to compute blood flow in large arteries as it is unable to capture wave reflections and transmissions when large variations of the arteries' geometrical and mechanical properties are considered. On the contrary, HR-S is exactly well-balanced and is the most accurate hydrostatic reconstruction technique. However, HR-LS is able to compute low-Shapiro number steady states as well as wave reflections and transmissions with satisfying accuracy and is simpler and computationally less expensive than HR-S. We therefore recommend using HR-LS for 1D blood flow simulations in large arterial network simulations.

physics.comp-ph↗

arXiv2016

Modeling rain-driven overland flow: empirical versus analytical friction terms in the shallow water approximation

Modeling and simulating overland flow fed by rainfall is a common issue in watershed surface hydrology. Modelers have to choose among various friction models when defining their simulation framework. The purpose of this work is to compare the simulation quality for the Manning, Darcy-Weisbach, and Poiseuille friction models on the simple case of a constant rain on a thin experimental flume. Results show that the usual friction law of Manning is not suitable for this type of flow. The Poiseuille friction model gave the best results both on the flux at the outlet and the velocity and depth profile along the flume. The Darcy-Weisbach model shows good results for laminar flow. Additional testing should be carried out for turbulent cases.

physics.flu-dyn↗

arXiv2013

Continuum simulation of the discharge of the granular silo: a validation test for the mu(I)-visco-plastic flow law

Using both a continuum Navier-Stokes solver, with the mu(I)-flow-law implemented to model the viscous behavior, and the discrete Contact Dynamics algorithm, the discharge of granular silos is simulated in two dimensions from the early stages of the discharge until complete release of the material. In both cases, the Beverloo scaling is recovered. We first do not attempt quantitative comparison, but focus on the qualitative behavior of velocity and pressure at different locations in the flow. A good agreement is obtained in the regions of rapid flows, while areas of slow creep are not entirely captured by the continuum model. The pressure field shows a general good agreement. The evolution of the free surface implies differences, however, the bulk deformation is essentially identical in both approaches. The influence of the parameters of the mu(I)-flow-law is systematically investigated, showing the importance of the dependence on the inertial number I to achieve quantitative agreement between continuum and discrete discharge. The general ability of the continuum model to reproduce qualitatively the granular behavior is found to be very encouraging.

cond-mat.soft↗