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2019 Blue Waters Symposium: Posters

Zachary Andalman

Evanston Township High School and Northwestern University

How does Stellar Spaghetti Circularize?

Abstract: When a star passes too close to a supermassive black hole (BH), the BH's tidal forces rip it apart into a spaghetti-like stream, leading to a tidal disruption event (TDE). In this work, we study the initial post-disruption phase of TDEs in general relativistic hydrodynamics using the code, H-AMR, developed in our group. The high efficiency of H-AMR and the power of the Blue Waters supercomputer GPUs allow us to simulate a TDE with realistic system parameters for the first time: namely, a black-hole-to-star mass ratio of one million and a parabolic stellar trajectory. We show that an accretion disk naturally forms due to the dissipation of orbital energy by compression shocks at the pericenter, with 20% of the infalling material forming the disk. After wrapping around the black hole, the stream intersects with itself. We find that these self-intersections can completely disrupt the stream, an effect seen in a TDE simulation for the first time. In fact, there are five such self-intersection events approximately 12 hours apart. These events have the potential to explain the flaring in the lightcurve of TDE Swift J1644+57 on a similar timescale.

Bryton Anderson

Boise State University

Computational Investigations of Surface Adsorption of Ethane on M1 Catalyst (Mo-V-Nb-Te-O)

Elaad Applebaum

Rutgers University

Looking Out for the Little Guy: A Comprehensive Study of Star Formation in Dwarf Galaxies

Mark Avara

Rochester Institute of Technology

3D-GRMHD Simulations of Binary Black Hole Accretion: Beyond 30 Orbits

Katelyn Barber

University of North Dakota

Characteristics of tropical and midlatitude out-of-cloud convectively-induced turbulence from high resolution convective simulations

Koushik Chatterjee

University of Amsterdam

Simulating a Tilted Black Hole Shadow

Abstract: Black holes are some of the most spectacular laboratories of physics due to the interplay between the strong gravity, matter, and electromagnetic fields. Since the infalling gas remains blissfully unaware of the black hole spin axis till very small distances, misalignment between the accretion disk and the black hole spin axis is likely to be common. For instance, indirect evidence for black hole tilt comes from quasi-periodic variability seen in many black hole accretion systems: such a variability can naturally arise from the Lense-Thirring precession of tilted accretion disks caused by the frame-dragging of spinning black holes. However, is there a way of measuring the disk tilt directly? A promising way of doing so is to observe the black hole shadow with the Event Horizon Telescope (EHT), an Earth-size radio interferometer. However, no first-principles models for the black hole shadow take the disk tilt into account, making it difficult to meaningfully interpret the upcoming EHT observations. Here, we present the first such model, made possible by the power of Blue Waters GPUs. Using our state-of-the-art GPU accelerated general relativistic magnetohydrodynamic code H-AMR, we have simulated tilted disks for a range of tilt angles and ray-traced the results. We discuss the changes that disk tilt introduces in the simulated black hole shadow images and spectra and the possibility of constraining the disk tilt from the highly anticipated EHT results, to be released later this year.

Shanna Chu

Stanford University

Source Processes of Intermediate-Depth Earthquakes

Robert L. Cieri

The University of Utah

Computational fluid dynamics modeling reveals a unique net-unidirectional pulmonary airflow patterns in monitor lizards (Varanidae)

Abigail C. Dommer

University of California San Diego

Microphysical climate-relevant properties of model marine aerosols explored with all-atom molecular dynamics simulations

Abstract: Marine aerosols impact climate by interacting with incoming solar radiation, serving as nuclei for cloud formation and providing interfaces for heterogeneous and multiphase atmospheric chemistry. Individual aerosol particles vary widely in their size, chemical composition, and morphology; however, current single-particle analysis techniques in the laboratory are unable to access the nanosecond to millisecond timescale dynamics within these aerosols, which ultimately control their reactivity, ability to take up water, nucleate ice, and form clouds. Thus, all-atom molecular dynamics (MD) simulations have become potent tools to complement laboratory investigations in the field of atmospheric chemistry.

In this work, the MD engine NAMD is used to model individual aerosol particles at the atomic level, with the goal of understanding how aerosol properties are modulated by particle size, organic mass fraction, and the internal mixing of organic and biological material. Model SSA are generated based on experimentally-determined aerosol lipidomic and proteomic information, ranging in size from 5 to 200 nm in diameter with up to 1x108 atoms. These monolithic system sizes are only accessible with the aid of Blue Waters world-class supercomputing. Model aerosol simulations with atomic resolution permit us to understand how particle size and chemical composition ultimately impact the dynamics and interactions within aerosols at the microscale, including protein and lipid partitioning, diffusion, and water transport across the interface, all of which allow us to make predictions about macroscale aerosol behavior. Variations in lipid and protein concentration are strongly modulated by biochemistry occurring at the ocean surface, which allows us to connect ocean microbiology to aerosol properties. Similarly, the variation in water content reflects the efflorescence and deliquescence of the particle, allowing us to link aerosol properties to relative humidity in the atmosphere.

The Blue Waters allocation awarded us to supplement our work in the NSF-Center for Aerosol Impacts on Chemistry of the Environment (NSF-CAICE) facilitates the integration of cutting-edge research in the laboratory with powerful computational modeling. This integration advances our capacity to accurately model marine aerosols and move us closer to unraveling the chemical complexity of marine aerosols and how it shapes our climate.

Andrew Emerick

Columbia University

Enabling Exascale Astrophysics: Galaxy-Scale Simulations with Enzo-E

Lakshay Gautam

University of Illinois at Urbana-Champaign

Phonon Dispersion calculations of Graphene, Graphite and AB stacked Bi-layer Graphene

Forrest Glines

Michigan State University

Magnetohydrodynamic Simulations of Turbulence in the Compressible Magnetized Taylor-Green Vortex

Alex Gurvich

Northwestern University

GPU Accelerated Time-Dependent Chemistry in the Context of Galaxy Formation with WIND

Joshua Lansford

University of Delaware

Electron Density-Based Machine Learning for Accelerating Quantum Calculations

Hui Li

Yale University

Impact of air-sea coupling on the simulated global tropical cyclone activity in the high-resolution Community Earth System Model (CESM)

Matthew Liska

University of Amsterdam

Pre-Exascale General Relativistic MHD Simulations of Ultra-thin Accretion Disks

Abstract: Luminous active galactic nuclei (AGN) and X-Ray binaries (XRBs) tend to be surrounded by geometrically thin, radiatively cooled accretion disks. According to both theory and observations, these are, in many cases, highly misaligned with the black hole spin axis. In this work we present the first general relativistic magnetohydrodynamic (GRMHD) simulations of very thin (h/r ~ 0.015 - 0.05) accretion disks around rapidly spinning (a ~ 0.9) black holes and tilted by 45-65 degrees. We show that the inner part of a highly tilted, h/r <= 0.03 disk aligns with the black hole spin, as predicted by theoretical work. In line with theory and contrary to previous GRMHD simulations at lower tilts, the inner aligned and outer misaligned disk are separated by a sharp {\it break} in tilt angle accompanied by a sharp drop in density. Especially when the tilt exceeds 60 degrees, frame-dragging by the spinning black hole overpowers disk viscosity, tearing the disk apart -- forming an inner disk that precesses rapidly, surrounded by a slowly precessing outer disk. In the innermost regions, jets precess rapidly with the inner disk, while jets precess slowly further out as they align partially with the outer sub-disk. If the tearing radius can be modeled accurately in future work, emission model independent measurements of black hole spin based on precession driven quasi-periodic oscillations may become possible.

Riccardo Longo

University of Illinois at Urbana-Champaign

Unravelling Nucleon Structure using Petascale Computing Resources

Abstract: Nuclear matter constitutes more than 99% of the mass of visible matter in the universe. Yet understanding the structure of the building blocks of atomic nuclei -protons and neutrons - in terms of their fundamental constituents - quarks and gluons - remains one of the most challenging tasks in particle physics. The dynamics and arrangement of quarks and gluons inside the nucleon are ruled by one of the four fundament interactions, the strong force, and are described within the theoretical approach of Quantum-Chromo-Dynamics (QCD).

The COMPASS experiment at CERN has between 2015 and 2018 collected more than 4 Petabytes of raw experimental data in nuclear collisions. The analysis of these data is pivotal to unravelling the dynamic nucleon structure. Before the physics quantities of interest can be extracted and interpreted, the raw data are converted into spatial hits in the detectors and energy deposits in the calorimeters. Then particle trajectories and momenta are reconstructed. The fast reconstruction and analysis of these data, together with the production of a considerable amount of simulated Monte Carlo data, place significant demands on the computing resources.

Thanks to the petascale resources provided by Blue Waters, COMPASS was able to carry out several data mass productions. The quasi-online processing of the 2018 sample represented one of the highlights of these campaigns. The reconstructed data were promptly analyzed and a preliminary result was made public this April at one of the important international conferences in the field (DIS in Turin, Italy).

An overview of the remarkable results obtained from the 2018 analysis is presented in this poster, giving particular attention to the fastest ever release of COMPASS data.

John McGarigal

University of Arkansas

Performance Analysis and Enhancements for Rayleigh-Taylor Instability Simulations

Lauren Pounds

Mississippi State University

Analyzing the Importance of Model Physics in Simulating Environments Associated with Tornadogenesis Within Tropical Cyclones

Nicole Rosato

Rochester Institute of Technology

Improved Trumpet Initial Lapse and Shift for Binary Black Hole Simulations

Swarnali Sanyal

University of Illinois at Urbana-Champaign

Ozone and PM2.5 exceedance events: How air quality is evolving under changing climate

Abstract: Here we investigate the impact of changing climate on air quality exceedance events in the future, focusing on PM2.5 and O3. The exceedance events give a measure of the impact of air quality on human health. Fully coupled global climate-chemistry model studies are used to simulate the present and two future scenarios using the Blue Waters system. We focus especially on the United States, India and China. The results show that the frequency of exceedance events increases in India for both the climate scenarios, but United States and China show an improvement for lower scenario. We also examine an ideal clean energy scenario, where mid-century fossil fuel emissions are reduced to zero. This study shows that by eliminating fossil fuels, both PM2.5 and O3 concentration reduce by 20 - 60% in high pollution regions.

Micheline Soley

Harvard University

Escaping from an ultracold inferno: computational chemistry at a new frontier in the ultracold KRb dimer reaction

Migle Surblyte

New Jersey Institute of Technology

Using High Performance Computing to Investigate Blood Clot Formation

Ruji Darius Teo

Duke University

Unraveling functional hole hopping pathways in the [4Fe4S]-containing DNA primase

Walter Torres

Duke University

The transport and dynamics of wave-driven reef jets under the influence of stratification and rotation

Samuel H. R. Whitman

University of Colorado Boulder

Simulation of Bluff-Body-Stabilized Flames Using PeleC, a Combustion Code for Exascale Computing