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Concept

Pitchfork bifurcation

Publications associées (24)

From thin plates to Ahmed bodies: linear and weakly nonlinear stability of rectangular prisms

Edouard Boujo, Giuseppe Antonio Zampogna

We study the stability of laminar wakes past three-dimensional rectangular prisms. The width-to-height ratio is set to W/H = 1.2, while the length-to-height ratio 1/6 < L/H < 3 covers a wide range of geometries from thin plates to elongated Ahmed bodies. F ...

Cambridge University Press2023

From coating flow patterns to porous body wake dynamics via multiscale models

Pier Giuseppe Ledda

Multiscale phenomena are involved in countless problems in fluid mechanics. Coating flows are known to exhibit a broad variety of patterns, such as wine tears in a glass and dripping of fresh paint applied on a wall. Coating flows are typically modeled und ...

EPFL2022

The effects of Prandtl number on the nonlinear dynamics of Kelvin-Helmholtz instability in two dimensions

Jeremy Peter Parker

It is known that the pitchfork bifurcation of Kelvin-Helmholtz instability occurring at minimum gradient Richardson number Ri(m) similar or equal to 1/4 in viscous stratified shear flows can be subcritical or supercritical depending on the value of the Pra ...

Cambridge University Press2021

Learning dynamical systems with bifurcations

Aude Billard, Farshad Khadivar, Ilaria Lauzana

Trajectory planning through dynamical systems (DS) provides robust control for robots and has found numerous applications from locomotion to manipulation. However, to date, DS for controlling rhythmic patterns are distinct from DS used to control point to ...

Elsevier2021

Global bifurcation at isolated singular points of the Hadamard derivative

Charles Stuart

Consider F is an element of C(RxX,Y) such that F(lambda, 0) = 0 for all lambda is an element of R, where X and Y are Banach spaces. Bifurcation from the line Rx{0} of trivial solutions is investigated in cases where F(lambda, center dot ) need not be Frech ...

2021

Receptor-induced transient responses in cells with oscillatory actin dynamics

Jose Negrete Jr

Living cells adjust their sensing and migratory machinery in response to changes in their environment. In this work, we show that cells of the social amoeba Dictyostelium discoideum modulate the dynamical state of their actin cytoskeleton in response to an ...

AMER PHYSICAL SOC2020

Qualitative properties and global bifurcation of solutions for a singular boundary value problem

Charles Stuart

This paper deals with a singular, nonlinear Sturm-Liouville problem of the form {A(x)u'(x)}'+ lambda u (x) = f (x, u(x), u'(x)) on (0,1) where A is positive on (0,1] but decays quadratically to zero as x approaches zero. This is the lowest level of degener ...

2020

Programmable Multistable Mechanisms: Design, modeling, characterization and applications

Mohamed Gamal Abdelrahman Ahmed Zanaty

Multistable Mechanisms are mechanical devices having more than one stable state. Since these mechanisms can maintain different deformations with zero force, they are advantageous for low power environments such as wristwatches and medical devices. In this ...

EPFL2018

Bifurcation Dynamics of a Particle-Encapsulating Droplet in Shear Flow

François Gallaire, Lailai Zhu

To understand the behavior of composite fluid particles such as nucleated cells and double emulsions in flow, we study a finite-size particle encapsulated in a deforming droplet under shear flow as a model system. In addition to its concentric particle-dro ...

American Physical Society2017

Dynamical Behavior and Stability Analysis of Hydromechanical Gates

Paolo Perona, Fabian Alexander Bernhard

This study revisits the stability of hydromechanical gates for upstream water surface regulation, also known as AMIL gates. AMIL gates are used in irrigation canals, where they are often installed in series. From the regulation perspective, instabilities a ...

American Society of Civil Engineers2017

Higher-order continuation method for the rigid-body kinematic design of compliant mechanisms

Simon Nessim Henein, Lennart Rubbert

Compliant mechanisms are of great interest in precision engineering. In this paper we propose a higher order continuation method to help their rigid-body kinematic design. The method helps to investigate the choice of a mechanism configuration through the ...

2017

Bifurcation points of a singular boundary-value problem on (0,1)

Charles Stuart

Following earlier work on some special cases [17,11] and on the analogous problem in higher dimensions [10,20], we make a more thorough investigation of the bifurcation points for a nonlinear boundary value problem of the form -{A(x)u' (x)}'.= f (lambda, x ...

Academic Press Inc Elsevier Science2016

Pushing amplitude equations far from threshold: application to the supercritical Hopf bifurcation in the cylinder wake

François Gallaire, Edouard Boujo, Philippe Meliga, Vladislav Mantic Lugo

The purpose of this review article is to push amplitude equations as far as possible from threshold. We focus on the Stuart-Landau amplitude equation describing the supercritical Hopf bifurcation of the flow in the wake of a cylinder for critical Reynolds ...

Iop Publishing Ltd2016

Fiber connectivity and bifurcation diagrams of almost toric integrable systems

Tudor Ratiu

We describe the bifurcation diagrams of almost toric integrable Hamiltonian systems on a four dimensional symplectic manifold M, not necessarily compact. We prove that, under a weak assumption, the connectivity of the fibers of the induced singular Lagrang ...

Int Press Boston, Inc2015

The temporal patterns of disease severity and prevalence in schistosomiasis

Andrea Rinaldo, Lorenzo Mari

Schistosomiasis is one of the most widespread public health problems in the world. In this work, we introduce an eco-epidemiological model for its transmission and dynamics with the purpose of explaining both intra-and inter-annual fluctuations of disease ...

American Institute of Physics2015

A self-consistent model for the saturation dynamics of the vortex shedding around the mean flow in the unstable cylinder wake

François Gallaire, Vladislav Mantic Lugo

The supercritical instability leading to the Benard-von Karman vortex street in a cylinder wake is a well known example of supercritical Hopf bifurcation: the steady solution becomes linearly unstable and saturates into a periodic limit cycle. Nonetheless, ...

Amer Inst Physics2015

The motion of a 2D pendulum in a channel subjected to an incoming flow

François Gallaire, Andrea Fani

The flow around a tethered cylinder subjected to an incoming flow transverse to its main axis and confined in a channel is investigated by means of global stability analysis of the full coupled body-fluid problem. When the cylinder is strongly confined (ra ...

Cambridge University Press2015

Exact soliton-like probability measures for interacting jump processes

Max-Olivier Hongler

The cooperative dynamics of a 1-D collection of Markov jump, interacting stochastic processes is studied via a mean-field (MF) approach. In the time-asymptotic regime, the resulting nonlinear master equation is analytically solved. The nonlinearity compens ...

2015

Heuristic strategies for the approximation of stability factors in quadratically nonlinear parametrized PDEs

Andrea Manzoni, Federico Negri

In this paper we present some heuristic strategies to compute rapid and reliable approximations to stability factors in nonlinear, inf-sup stable parametrized PDEs. The efficient evaluation of these quantities is crucial for the rapid construction of a pos ...

Springer Verlag2015

Bifurcation without Frechet differentiability at the trivial solution

Charles Stuart

Criteria for the bifurcation of small solutions of an equation F(lambda,u) = 0 from a line {(lambda,0): lambda is an element of R} of trivial solutions are usually based on properties of the DuF(lambda,0) at the trivial solutions, where the partial derivat ...

Wiley-Blackwell2015