Publication

An intercomparison of subgrid models for large-eddy simulation of katabatic flows

Publications associées (21)

Physics-Informed Machine Learning for Modeling and Control of Dynamical Systems

Colin Neil Jones, Melanie Nicole Zeilinger, Xuan Truong Nghiem, Roland Schwan

Physics-informed machine learning (PIML) is a set of methods and tools that systematically integrate machine learning (ML) algorithms with physical constraints and abstract mathematical models developed in scientific and engineering domains. As opposed to ...

IEEE2023

Identifying invariant solutions of wall-bounded three-dimensional shear flows using robust adjoint-based variational techniques

Tobias Schneider, Omid Ashtari

Invariant solutions of the Navier-Stokes equations play an important role in the spatiotemporally chaotic dynamics of turbulent shear flows. Despite the significance of these solutions, their identification remains a computational challenge, rendering many ...

Cambridge University Press2023

Anomaly-free scale symmetry and gravity

Mikhail Chapochnikov, Anna Tokareva

In this Letter, we address the question of whether the conformal invariance can be considered as a global symmetry of a theory of fundamental interactions. To describe Nature, this theory must contain a mechanism of spontaneous breaking of the scale symmet ...

ELSEVIER2023

Invariant solutions underlying small- and large-scale structures in turbulent boundary layers

Sajjad Azimi

Flows of gases and liquids interacting with solid objects are often turbulent within a thin boundary layer. As energy dissipation and momentum transfer are dominated by the boundary layer dynamics, many engineering applications can benefit from an improved ...

EPFL2020

Atomistic modeling of the solid-liquid interface of metals and alloys

Edoardo Baldi

Solidification is a phase transformation of utmost importance in material science, for it largely controls materials' microstructure on which a wide range of mechanical properties depends. Almost every human artifact undergoes a transformation that leads t ...

EPFL2020

A structural test for the conformal invariance of the critical 3d Ising model

João Miguel Augusto Penedones Fernandes, Pierre Mathieu Yvernay

How can a renormalization group fixed point be scale invariant without being conformal? Polchinski (1988) showed that this may happen if the theory contains a virial current a non-conserved vector operator of dimension exactly (d - 1), whose divergence exp ...

Springer Nature2019

Adaptive numerical method algorithms for nonlinear viscous and bilinear oil damper models subjected to dynamic loading

Dimitrios Lignos

Adaptive numerical method algorithms are presented for the numerical simulation of the hysteretic behaviour of nonlinear viscous and bilinear oil dampers within a finite element program for nonlinear dynamic analysis of frame structures under earthquake ex ...

2018

Intercomparison of Terrain-Following Coordinate Transformation and Immersed Boundary Methods for Large-Eddy Simulation of Wind Fields over Complex Terrain

Jiannong Fang, Fernando Porté Agel

Accurate modeling of complex terrain, especially steep terrain, in the simulation of wind fields remains a challenge. It is well known that the terrain-following coordinate transformation method (TFCT) generally used in atmospheric flow simulations is rest ...

2016

Poincaré, Scale and Conformal Symmetries : Gauge Perspective and Cosmological Ramifications

Georgios Karananas

Symmetries are omnipresent and play a fundamental role in the description of Nature. Thanks to them, we have at our disposal nontrivial selection rules that dictate how a theory should be constructed. This thesis, which is naturally divided into two parts, ...

EPFL2016

Control of agent swarms in random environments

Guillaume Adrien Sartoretti

The collective dynamic behavior of large groups of interacting autonomous agents (swarms) have inspired much research in both fundamental and engineering sciences. It is now widely acknowledged that the intrinsic nonlinearities due to mutual interactions c ...

EPFL2016

Elastocapillary coalescence of plates and pillars

Tobias Schneider, Ji Hyun Kim

When a fluid-immersed array of supported plates or pillars is dried, evaporation leads to the formation of menisci on the tips of the plates or pillars that bring them together to form complex patterns. Building on prior experimental observations, we use a ...

Royal Soc2015

Turbulent scale resolving modelling of rotating stall in low-pressure steam turbines operated under low volume flow conditions

Peter Ott, Benjamin Megerle, Ivan William McBean

Non-synchronous excitation under low volume operation is a major risk to the mechanical integrity of last stage moving blades (LSMBs) in low-pressure (LP) steam turbines. These vibrations are often induced by a rotating aerodynamic instability similar to r ...

2015

From Scale Invariance to Lorentz Symmetry

Sergey Sibiryakov

It is shown that a unitary translationally invariant field theory in 1 + 1 dimensions, satisfying isotropic scale invariance, standard assumptions about the spectrum of states and operators, and the requirement that signals propagate with finite velocity, ...

Amer Physical Soc2014

Evolution and selection of river networks: Statics, dynamics, and complexity

Andrea Rinaldo, Amos Maritan

Moving from the exact result that drainage network configurations minimizing total energy dissipation are stationary solutions of the general equation describing landscape evolution, we review the static properties and the dynamic origins of the scale-inva ...

National Academy of Sciences2014

On the Development of a Dynamic Non-linear Closure for Large-Eddy Simulation of the Atmospheric Boundary Layer

Fernando Porté Agel, Hao Lu

A dynamic procedure is developed to compute the model coefficients in the recently introduced modulated gradient models for both momentum and scalar fluxes. The magnitudes of the subgrid-scale (SGS) stress and the SGS flux are estimated using the local equ ...

Springer2014

Spontaneously broken conformal symmetry: dealing with the trace anomaly

Mikhail Chapochnikov, Alexander Monin, Roberta Armillis

The majority of renormalizable field theories possessing the scale invariance at the classical level exhibits the trace anomaly once quantum corrections are taken into account. This leads to the breaking of scale and conformal invariance. At the same time ...

Springer Nature2013

Evaluation of subgrid-scale models in large-eddy simulation of flow past a two-dimensional block

Fernando Porté Agel, Wai Chi Cheng

Large-eddy simulations of flow past a two-dimensional (2D) block were performed to evaluate four sub-grid-scale (SGS) models: (i) the traditional Smagorinsky model, (ii) the Lagrangian dynamic model, (iii) the Lagrangian scale-dependent dynamic model, and ...

Elsevier2013

Dynamics of the head of gravity currents

Mário Jorge Rodrigues Pereira Da Franca, Helena Isabel Dos Santos Nogueira, Claudia Adduce

The present work experimentally investigates the dynamics of unsteady gravity currents produced by lock-release of a saline mixture into a fresh water tank. Seven different experimental runs were performed by varying the density of the salinemixture in the ...

Springer Verlag2013

The Effect of Scale on the Applicability of Taylor’s Frozen Turbulence Hypothesis in the Atmospheric Boundary Layer

Valentin Simeonov, Martin Froidevaux, Nikki Vercauteren, Marc Parlange, Chad Higgins, Caitlin Ellen Barry

Taylor’s frozen turbulence hypothesis is the central assumption invoked in most experiments designed to investigate turbulence physics with time resolving sensors. It is also frequently used in theoretical discussions when linking Lagrangian to Eulerian fl ...

2012

Large-Eddy Simulation of Stably-Stratified Flow Over a Steep Hill

Fernando Porté Agel

Large-eddy simulation (LES) is used to simulate stably-stratified turbulent boundary-layer flow over a steep two-dimensional hill. To parametrise the subgrid-scale (SGS) fluxes of heat and momentum, three different types of SGS models are tested: (a) the S ...

Springer Netherlands2011