A5079801182- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Fluid Dynamics and Turbulent Flows
- Geomagnetism and Paleomagnetism Studies
- Oceanographic and Atmospheric Processes
- Stellar, planetary, and galactic studies
- Meteorological Phenomena and Simulations
- Geophysics and Gravity Measurements
- Advanced Thermodynamics and Statistical Mechanics
- Astrophysics and Star Formation Studies
- Spectroscopy and Quantum Chemical Studies
- Numerical methods for differential equations
- Ocean Waves and Remote Sensing
- Computational Fluid Dynamics and Aerodynamics
- Quantum, superfluid, helium dynamics
- Ionosphere and magnetosphere dynamics
- Nanofluid Flow and Heat Transfer
- Micro and Nano Robotics
- Methane Hydrates and Related Phenomena
- Astronomy and Astrophysical Research
- Advanced Numerical Methods in Computational Mathematics
- Tropical and Extratropical Cyclones Research
- History and Developments in Astronomy
- Electromagnetic Scattering and Analysis
- Advanced Data Storage Technologies
Massachusetts Institute of Technology
2015-2025
Flatiron Health (United States)
2019-2024
Flatiron Institute
2019-2024
Cornell University
2022
Simons Foundation
2019-2020
IIT@MIT
2018
University of California, Santa Barbara
2014-2015
Search for Extraterrestrial Intelligence
2010-2012
University of California, Berkeley
2010-2012
United States Department of Commerce
1980
This paper describes Dedalus, an open-source Python code for simulating partial differential equations from all areas of physics. Dedalus translates plain-text into efficient and parallelized solvers using global spectral methods. Here the authors detail numerical methods enabling this translation describe code's design implementation. They also illustrate its capabilities with diverse examples, including optical network dynamics, magnetized shocks in plasmas, large-scale oceanic flows, low...
We describe the vision, user interface, governing equations, and numerical methods that underpin new ocean modeling software called ``Oceananigans''. Oceananigans is being developed by Climate Modeling Alliance as part of a larger project to build trainable climate model with quantifiable uncertainty. argue status popular, capable system realizes vision for accelerating progress in Earth balances demands accuracy performance, needed state-of-the-art science, against accessibility, which...
Abstract We describe CATKE, a parameterization for fluxes associated with small‐scale or “microscale” ocean turbulent mixing on scales between 1 and 100 m. CATKE uses downgradient formulation that depends prognostic kinetic energy (TKE) variable diagnostic length scale includes dynamic convective adjustment (CA) component. With its length, predicts not just the depth spanned by plumes but also characteristic timescale, an important aspect of convection captured simpler static CA schemes. As...
The nonlinear evolution of the Kelvin-Helmholtz instability is a popular test for code verification. To date, most problems discussed in literature are ill-posed: they do not converge to any single solution with increasing resolution. This precludes comparisons among different codes and severely limits utility as problem. lack reference has led various authors assert accuracy their simulations based on ad-hoc proxies, e.g., existence small-scale structures. paper proposes well-posed smooth...
Abstract The magnetic dynamo cycle of the Sun features a distinct pattern: propagating region sunspot emergence appears around 30° latitude and vanishes near equator every 11 years (ref. 1 ). Moreover, longitudinal flows called torsional oscillations closely shadow migration, undoubtedly sharing common cause 2 . Contrary to theories suggesting deep origins these phenomena, helioseismology pinpoints low-latitude outer 5–10% Sun, near-surface shear layer 3,4 Within this zone, inwardly...
Water's density maximum at 4°C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable convection below 4°C, but stably stratified above 4°C. We present numerical simulations of a waterlike fluid near its in two-dimensional domain. successfully model the damping waves using linear theory, provided we do not take weak limit typically used literature. To isolate physical mechanism exciting waves, use spectral code dedalus run...
Bowman et al. (2019) reported low-frequency photometric variability in 164 O- and B-type stars observed with K2 TESS. They interpret these motions as internal gravity waves, which could be excited stochastically by convection the cores of stars. The detection waves massive would help distinguish between convective or radiative cores, determine core size, provide important constraints on star structure evolution. In this work, we study observational signature generated convection. We...
Massive stars die in catastrophic explosions that seed the interstellar medium with heavy elements and produce neutron black holes. Predictions of explosion's character remnant mass depend on models star's evolutionary history. Models massive star interiors can be empirically constrained by asteroseismic observations gravity wave oscillations. Recent photometric reveal a ubiquitous red noise signal main sequence stars; hypothesized source this is waves driven core convection. We present...
Aims. In this paper we present the first on-sky results with fibered aperture masking instrument FIRST. Its principle relies on combination of spatial filtering and using single-mode fibers, a novel technique that is aimed at high dynamic range imaging angular resolution.
Asteroseismology probes the interiors of stars by studying oscillation modes at a star's surface. Although pulsation spectra are well understood for solar-like oscillators, substantial fraction red giant observed Kepler exhibit abnormally low-amplitude dipole modes. Fuller et al. (2015) suggests this effect is produced strong core magnetic fields that scatter internal gravity waves (IGWs) into higher multipole IGWs or waves. In paper, we study interaction with field to test mechanism. We...
This paper presents a method for accurate and efficient computations on scalar, vector tensor fields in three-dimensional spherical polar coordinates. The uses spin-weighted harmonics the angular directions rescaled Jacobi polynomials radial direction. For 2-sphere, allow automating calculations fashion as similar to Fourier series possible. Derivative operators act wavenumber multiplication set of spectral coefficients. After transforming directions, orthogonal rotations put radially...
Recent experiments demonstrate the importance of substrate curvature for actively forced fluid dynamics. Yet, covariant formulation and analysis continuum models nonequilibrium flows on curved surfaces still poses theoretical challenges. Here, we introduce study a generalized Navier-Stokes model driven by active stresses in nonplanar geometries. The analytical tractability theory is demonstrated through exact stationary solutions case spherical bubble geometry. Direct numerical simulations...
Thermal conduction is an important energy transfer and damping mechanism in astrophysical flows. Fourier's law - the heat flux proportional to negative temperature gradient, leading diffusion a well-known empirical model of thermal conduction. However, entropy has emerged as alternative model, despite not ensuring monotonicity entropy. This paper investigates differences between for both linear internal gravity waves weakly nonlinear convection. In addition simulating two models with fully...
ABSTRACT It has been proposed that mixing induced by convective overshoot can disrupt the inward propagation of carbon deflagrations in super-asymptotic giant branch stars. To test this theory, we study an idealized model convectively bounded flames with 3D hydrodynamic simulations Boussinesq equations using pseudo-spectral code Dedalus. Because flame timescale is much longer than convection timescale, approximate as fixed space, and only consider its effects on buoyancy fluid. By evolving a...
We present a simulation code which can solve broad range of partial differential equations in full sphere. The expands tensorial variables spectral series spin-weighted spherical harmonics the angular directions and scaled Jacobi polynomial basis radial direction, as described Vasil et al. (2018; hereafter, Part-I). Nonlinear terms are calculated by transforming from coefficients to value each quantity on physical grid, where it is easy calculate products perform other local operations....
M-dwarf stars below a certain mass are convective from their cores to photospheres. These fully objects extremely numerous, very magnetically active, and the likely hosts of many exoplanets. Here we study, for first time, dynamo action in simulations stratified, rotating stars. Importantly, use new techniques capture correct full ball geometry down center star. We find surprising states these systems, with global-scale mean fields confined strongly single hemisphere, contrast prior stellar...
We discuss the use of systematic ‘a posteriori’ calibration in development complicated (but theory-based) parameterizations. With calibration, model error is assessed using results forward simulations, thereby incorporating numerical error, stability, model-specific implementation details,  and alleviating need for explicit data all parameterized components. show how illuminates parameterization trade-off between reductions bias, producing better predictions, and...