Four idealized direct numerical simulations are performed to examine the dynamics arising from the superposition of a monochromatic gravity wave (GW) and sinusoidal linear and rotary fine structure in the velocity field. These simulations are motivated by the ubiquity of such multiscale superpositions throughout the atmosphere. Three simulations explore the effects of linear fine structure alig...

The unsteady, incompressible Navier-Stokes equations are used for the direct numerical simulation (DNS) of spatially evolving disturbances in a threedimensional (3-D) attachment-line boundary layer. Two-dimensional (2-D) disturbances are introduced either by forcing at the in ow or by harmonic-source generators at the wall; 3-D disturbances are introduced by harmonic-source generators at the wa...

Instabilities in solids and structures are ubiquitous across all length and time scales, and engineering design principles have commonly aimed at preventing instability. However, over the past two decades, engineering mechanics has undergone a paradigm shift, away from avoiding instability and toward taking advantage thereof. At the core of all instabilities—both at the microstructural scale in...

The objective of this contribution is to establish a computational framework to study growth-induced instabilities. The common approach towards growth-induced instabilities is to decompose the deformationmultiplicatively into its growth and elastic part. Recently, this concept has been employed in computations of growing continua and has proven to be extremely useful to better understand the ma...

The electron beam which IS accelerated in the SLAC two-mile accelerator exhibits both transverse and longitudinal interactions with the disk-loaded waveguide, The transverse interactions include such effects as rf steering caused by field asymmetries which exist in the couplers, and beam breakup, The latter is a growing instability which occurs above a given current threshold and deflects the b...

In [2], F.Linares, G.Ponce, J-C.Saut have proved that a non-fully dispersive Zakharov system arising in the study of Laser-plasma interaction, is locally well posed in the whole space, for fields vanishing at infinity. Here we show that in the periodic case, seen as a model for fields non-vanishing at infinity, the system develops strong instabilities of Hadamard’s type, implying that the Cauch...

The main goal of this paper is to prove that if the energymomentum (or energy-Casimir) method predicts formal instability of a relative equilibrium in a Hamiltonian system with symmetry, then with the addition of dissipation, the relative equilibrium becomes spectrally and hence linearly and nonlinearly unstable. The energy-momentum method assumes that one is in the context of a mechanical syst...

Machine studies have been conducted in the SPS to better characterise the transverse instabilities observed on the LHC beam by the beam induced electron cloud. Most of the observations have been performed at injection energy. Different beam configurations have been considered as a function of their availability from the injectors. The results of these observations (bunch centroid motion, head-t...

In the hydrodynamic description of ferronematics there are various dynamic magnetic-field effects, linear in the field strength, that are negligible in usual nematics, but can play a role in ferronematics. Here, we investigate theoretically the influence of these new terms on the thermal convection (Rayleigh-Bénard) and the viscous fingering (Saffman-Taylor) instability in ferronematics in the ...

A defining property of massive stars is the dominant, dynamical role played by radiation throughout the stellar interior, atmosphere, and wind. Associated with this radiation hydrodynamics are several distinct kinds of instabilities that can lead to convection in both core and envelope, clumping in atmosphere and wind outflow, and perhaps even the dramatic mass loss outbursts associated with Lu...