H2020Индивидуална стипендия2019–2021

StratifiedGRANULAR · Modelling of rheologically stratified granular flows by a multi-layer depth-averaged approach

„Хоризонт 2020“ — Действия „Мария Склодовска-Кюри“

Период: 2019-10-01 → 2021-09-30
Финансиране от ЕС: 159 461 €
Участници: 1
Схема: MSCA-IF-EF-ST

Линиите свързват координатора с партньорите.

Накратко на български

Потоците от гранулирани материали, като например каменно-ледените лавини, се анализират чрез нови математически модели за многослойно движение. Разбирането на тези процеси помага за по-добра оценка на рисковете за хората и инфраструктурата.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Modelling of rheologically stratified granular flows by a multi-layer depth-averaged approach

Geophysical granular flows are a major hazard to men and infrastructures. This MSCA project is intended to develop a multi-layer model for describing highly-sheared granular flows characterized by a rheological stratification. The project aims at: (1) overcoming the mathematical issues related to the loss of hyperbolicity; (2) describing the essential physics of granular avalanches, whose rheology is strongly depending on the solid volume fraction. The MSCA researcher developed a well-posed depth-averaged model, where various layers are advected in a dynamically coupled way. The stress and shear-rate tensors are related through the well-established µ(I) rheology. The evolution of the volume fraction is captured by an advection-diffusion transport equation that incorporates a dilatancy law depending on the inertial number. To avoid short-wave instabilities of Hadamard type, a physically-based viscous regularization, using an approximation of the in-plane stress gradients, is proposed. The model has been numerically integrated by a finite volume scheme with a high-resolution lateralized Harten–Lax–van Leer (LHLL) solver. For the comparison with the velocity and volume fraction profiles in steady state, an experimental dataset from the Environmental and Maritime Hydraulics Laboratory (LIDAM) of the University of Salerno (Italy) has been used, where the sidewall velocity profiles have been obtained by granular particle image velocimetry, g-PIV (Sarno et al., Adv. Powder Technol., 2018), and the near-wall volume fraction profiles have been estimated by the stochastic-optical method, SOM (Sarno et al., Granul. Matter, 2016). Additional experimental datasets from the literature have been used to validate the model in the transient state. The objectives of the project have been: (1) development of a multi-layer model for granular flows, where a suitable constitutive law is implemented and the evolution of the volume fraction is consistently considered; (2) taking into account the effects due to irregular topographies; (3) numerical integration of the model; (4) validation of the model through laboratory experiments; (5) broadening the skills of the MSCA researcher in mathematical modelling and computational fluid dynamics; (6) helping the MSCA researcher to develop scientific independence.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

Geophysical granular flows, like rock avalanches and debris flows, represent a serious hazard to life and infrastructures in Europe. Yet their dynamics is still far from being completely understood. Recent experimental investigations on granular flows showed that velocity and solid volume fraction exhibit a stratified pattern along the flow depth. This indicates the superimposition of different rheological regimes. Moreover, non-local rheological theories have been recently proposed for capturing momentum exchanges, driven by the occurrence of force chains.The present multidisciplinary project aims at developing a computationally cost-effective multi-layer depth-averaged model for describing rheologically stratified granular flows. The model, having much lower computational costs than three-dimensional models, will be designed to capture the essential physics of granular flows in the depth-wise direction. To properly take into account the curvature effects due to basal topography, the model equations will be derived in curvilinear coordinates attached to the topography. Moreover, a suitable non-local constitutive law will be incorporated. The resulting equations will be numerically integrated by a proper finite volume scheme, taking into account their main mathematical properties, i.e. non-strict hyperbolicity and non-conservative form. The model validation will be carried out by using a wide experimental data set, previously gathered by the applicant on dry granular flows. The last stage of the project is devoted to extending the multi-layer approach to cases with dense interstitial fluid, so as to allow its application to debris flows.In line with H2020 priorities, especially as regards sustainable human settlements and their resilience to natural hazards due to climate changes, the project has the potential to provide an advanced mathematical-numerical tool for better identifying the hazardous areas associated with avalanches and debris flows.

Оригинален текст от CORDIS (на английски).

Участници

TECHNISCHE UNIVERSITAT DARMSTADT · DarmstadtКоординаторГермания