A5101434539- Fluid Dynamics and Turbulent Flows
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Particle Dynamics in Fluid Flows
- Stellar, planetary, and galactic studies
- Geophysics and Sensor Technology
- Oceanographic and Atmospheric Processes
- Seismic Waves and Analysis
- Meteorological Phenomena and Simulations
- Complex Systems and Time Series Analysis
- Aerodynamics and Fluid Dynamics Research
- Tropical and Extratropical Cyclones Research
- Cognitive Science and Education Research
- Topology Optimization in Engineering
- Reservoir Engineering and Simulation Methods
- Fluid Dynamics and Vibration Analysis
- Vehicle Noise and Vibration Control
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- Lattice Boltzmann Simulation Studies
- Tribology and Lubrication Engineering
- Simulation Techniques and Applications
- Material Dynamics and Properties
University of California, Berkeley
2008-2021
National Energy Research Scientific Computing Center
2021
Machine learning (ML) provides novel and powerful ways of accurately efficiently recognizing complex patterns, emulating nonlinear dynamics, predicting the spatio-temporal evolution weather climate processes. Off-the-shelf ML models, however, do not necessarily obey fundamental governing laws physical systems, nor they generalize well to scenarios on which have been trained. We survey systematic approaches incorporating physics domain knowledge into models distill these broad categories....
There is considerable interest in hydrodynamic instabilities dead zones of protoplanetary disks as a mechanism for driving angular momentum transport and source particle-trapping vortices to mix chondrules incubate planetesimal formation. We present simulations with pseudo-spectral anelastic code the compressible Athena, showing that stably stratified flows shearing, rotating box are violently unstable produce space-filling, sustained turbulence dominated by large Rossby numbers order...
A previously unknown instability creates space-filling lattices of 3D vortices in linearly stable, rotating, stratified shear flows. The starts from an easily excited critical layer. layer intensifies by drawing energy the background and rolls up into that excite new layers vortices. self-similarly replicate to create turbulent persist for all time. This self-replication occurs Couette flows dead zones protoplanetary disks where it can destabilize Keplerian
ABSTRACT In Zombie Vortex Instability (ZVI), perturbations excite critical layers in stratified, rotating shear flow (as protoplanetary disks (PPDs)), causing them to generate vortex layers, which roll up into anticyclonic zombie vortices and cyclonic sheets. The process is self-sustaining as perturb new spawning a next generation of vortices. Here, we focus on two issues: the minimum threshold that trigger generation, properties late-time turbulence large small scales. parameter determines...
Two intersecting beams of internal gravity waves will generically create two wave packets by nonlinear interaction. The frequency one packet be the sum and that other difference frequencies beams. In principle, each should form an "X" pattern, or "St. Andrew's cross" consisting four outgoing from point intersection. Here we derive selection rules show most expected are forbidden. These can also applied to reflection a beam boundary.
The linear stability of three-dimensional vortices in rotating, stratified flows has been studied by analysing the non-hydrostatic inviscid Boussinesq equations. We have focused on a widely used model geophysical and astrophysical vortices, which assumes an axisymmetric Gaussian structure for pressure anomalies horizontal vertical directions. For range Rossby numbers ( $-0.5<Ro<0.5$ ) Burger $0.02<Bu<2.3$ relevant to observed long-lived growth rate spatial most unstable...
We show that the “dead” zone of a protoplanetary disk fills with robust 3D vortices from purely hydrodynamic instability. This new instability is not linear and requires weak finite-amplitude initial perturbation. The was seen previously either due to lack numerical spatial resolution, or because many previous simulations ignored vertical gravity had flows constant density. Our family previously-unknown critical layers form in rotating, shearing, vertically stratified like those disks....