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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,513 records · Page 84
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Final Project Report

Most climate models are currently run with grid spacings of around 100km, which, with today’s computing power, allows for long (up to 1000 year) simulations, or ensembles of simulations to explore climate change and variability. However this grid spacing does not resolve important components of the weather/climate system such as atmospheric fronts and mesoscale systems, and ocean boundary currents and eddies. The overall aim of this project has been to look at the effect of these small-scale features on the weather/climate system using a suite of high and low resolution climate models, idealized models and observations. This project was only possible due to the highly scalable aspect of the CAM Spectral Element dynamical core, and the significant resources allocated at Yellowstone and NERSC for which we are grateful.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Research and Development for the Mu2e Extinction Monitor

Mu2e is a planned experiment to search for flavor-violating conversion from a muon to an electron. The experiment will use a pulsed 8 GeV proton beam to produce muons which will then stop in an aluminum target. Mu2e will search for the $\mu^- + Al \rightarrow e^- + Al$ process. For Mu2e, an extinction rate of 10$^{-10}$ is required to reduce the backgrounds to an acceptable level. Extinction is the ratio of the amount of protons striking the production target between beam pulses to the number striking it during the beam pulse. One of the backgrounds, off-target interactions, was simulated using G4beamline and Fermilab's Grid setup to confirm that an extinction rate of 10$^{-10}$ is possible. The extinction level will be measured by the extinction monitor which will include scintillation counters read out by photomultiplier tubes. In order to build a beam time profile, low fake responses (after pulses) are needed in the photomultiplier tubes. This thesis determines the best combination of resistors, voltage, and other components that provide the lowest after pulse rate.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Evaluating the Impact of Ocean Eddies in the Global Marine Carbon Cycle

The ocean plays a crucial role in the Earth’s carbon cycle due to its ability to exchange carbon dioxide (CO2) with the atmosphere, and subsequently store it for long periods of time. Part of this sequestration is due to a mechanism known as the Biological Pump, a process where phytoplankton and autotrophic bacteria convert dissolved CO2 to organic matter via photosynthesis, much of which ends up sinking and can remain in the deep ocean for hundreds or thousands of years. If the strength of the Biological Pump changes due the human-induced increase in atmospheric CO2, it will affect the rate of global warming. Earth System Models (ESMs) are now including ocean biogeochemical processes in order to quantify changes in the global carbon cycle under climate change scenarios by embedding a model that represents ocean chemistry and the dynamics of marine ecosystems within an ocean circulation framework. Due to the increased computational cost of including marine biogeochemistry (BGC), they are typically run with relatively low complexity and coarse horizontal grid resolution. Our project utilizes Institutional Computing power to undertake an ESM simulation using a moderate complexity BGC model (35 constituents) and an increased grid resolution that allows the formation of turbulent mesoscale eddies (30 to 200 km in size) in the ocean. Comparing with low resolution runs will allow us to assess whether standard ESMs are biased in their representation of the carbon cycle due to parameterized effects of sub-grid scale physics.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Evaluating the Impact of Ocean Eddies in the Global Marine Carbon Cycle

The ocean plays a crucial role in the Earth’s carbon cycle due to its ability to exchange carbon dioxide (CO 2 ) with the atmosphere, and subsequently store it for long periods of time. Part of this sequestration is due to a mechanism known as the Biological Pump, a process where phytoplankton and autotrophic bacteria convert dissolved CO 2 to organic matter via photosynthesis, much of which ends up sinking and can remain in the deep ocean for hundreds or thousands of years. If the strength of the Biological Pump changes due the human-induced increase in atmospheric CO 2 , it will affect the rate of global warming. Earth System Models (ESMs) are now including ocean biogeochemical processes in order to quantify changes in the global carbon cycle under climate change scenarios by embedding a model that represents ocean chemistry and the dynamics of marine ecosystems within an ocean circulation framework. Due to the increased computational cost of including marine biogeochemistry (BGC), they are typically run with relatively low complexity and coarse horizontal grid resolution. Our project utilizes Institutional Computing power to undertake an ESM simulation using a moderate complexity BGC model (35 constituents) and an increased grid resolution that allows the formation of turbulent mesoscale eddies (30 to 200 km in size) in the ocean. Comparing with low resolution runs will allow us to assess whether standard ESMs are biased in their representation of the carbon cycle due to parameterized effects of sub-grid scale physics.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Flexible Service Contracting for Risk Management within Integrated Transmission and Distribution Systems

The general objective of our project has been to investigate the ability of Independent Distribution System Operators (IDSOs), functioning as linkage agents for Integrated Transmission and Distribution (ITD) systems, to facilitate the flexible availability and usage of reserve in support of ITD system operations. This general objective is in accordance with Order 2222 of the U.S. Federal Energy Regulatory Commission (FERC), titled “Participation of Distributed Energy Resource Aggregations in Markets Operated by Regional Transmission Organizations and Independent System Operators”. The Final Rule for FERC Order 2222 was issued on September 17, 2020. The primary contribution of our project is that we have formulated an innovative energy management Transactive Energy Design (TES) approach for ITD systems that provides promising support for our project objective. Specifically, we have developed a new type of IDSO-managed TES design for distribution system operations, as well as new types of swing contracts permitting IDSOs to participate in transmission system operations as providers of reserve harnessed from distribution system resources in return for appropriate compensation. Together, these design elements constitute a scalable market-based approach facilitating efficient reserve procurement for ITD system operations from a fuller range of power resources. The efficacy of our approach has been demonstrated by means of detailed conceptual analyses as well as test case simulations. To implement the latter, we have developed the ITD TES Platform V2.0, a computational platform that permits the modeling and software implementation of ITD system operations over time. The Electric Reliability Council of Texas (ERCOT) energy region has been used as the empirical anchor for the development of this platform. Our conceptual and test-case work has been reported in a Wiley/IEEE Press book, two refereed book chapters, and seven refereed journal articles. The key components comprising the ITD TES Platform V2.0 have been released as documented open-source software at online GitHub repositories.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

Tidal Resource Gaps Analysis Technical Report

The tidal resource gaps project was created to address a growing body of evidence that models underpredict tidal current speeds compared to measurements at a number of the top-ranking tidal energy sites. In response, this project compared opportunistic tidal power density measurements from 16 tidal energy hot spot sites with estimates from resource assessment data to identify discrepancies. To improve the accuracy of resource estimates from model data, updated data from eight improved model simulations were obtained. Model improvements included grid refinement, domain coupling, and the use of unstructured or nested grids. New resource estimates were calculated from the updated models, and these data were used to update the tidal hot spots-a list of promising tidal energy sites around the United States.

16 TIDAL AND WAVE POWER↗
DOE OSTI2024

Object-Oriented Controllable High-Resolution Residential Energy (OCHRE) (TM) Model

This presentation describes the OCHRE model as part of NREL's Powered By webinar series. OCHRE is a building energy modeling tool designed to model flexible loads in residential buildings. OCHRE includes detailed models and controls for flexible devices including HVAC equipment, water heaters, electric vehicles, solar PV, and batteries. It is designed to run in co-simulation with custom controllers, aggregators, and grid models.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

Hardware-in-the-Loop Using Electromagnetic Transient Simulation

Digital real time simulators have the capability to run electromagnetic transient simulations in real time. This capability allows users to leverage the hardware-software combination to evaluate controller performance, protection device performance, and power device performance. This has helped many field deployment projects to be successful and be cost-effective. In this talk, we will present current state-of-art, and future of real time electromagnetic transient simulation and its impacts on field deployment.

08 HYDROGEN↗
DOE OSTI2020

Results for Voisin et al. 2020 [Data set]

These data files provide contemporary (2010) bulk electricity grid operations and transmission flow as simulated by PLEXOS and informed by historical and future generation constraints scenarios as informed by historical and future water availability at hydro and thermoelectric plants. Contact: Ana Dyreson , Nathalie Voisin Authors: Nathalie Voisin, Ana Dyreson, Tao Fu, Matt O'Connell, Sean Turner, Tian Zhou, Jordan Macknick

13 HYDRO ENERGY↗
DOE OSTI2022

Kilonova Detectability with Wide-field Instruments

Abstract Kilonovae are ultraviolet, optical, and infrared transients powered by the radioactive decay of heavy elements following a neutron star merger. Joint observations of kilonovae and gravitational waves can offer key constraints on the source of Galactic r -process enrichment, among other astrophysical topics. However, robust constraints on heavy element production require rapid kilonova detection (within ∼1 day of merger) as well as multiwavelength observations across multiple epochs. In this study, we quantify the ability of 13 wide-field-of-view instruments to detect kilonovae, leveraging a large grid of over 900 radiative transfer simulations with 54 viewing angles per simulation. We consider both current and upcoming instruments, collectively spanning the full kilonova spectrum. The Roman Space Telescope has the highest redshift reach of any instrument in the study, observing kilonovae out to z ∼ 1 within the first day post-merger. We demonstrate that BlackGEM, DECam, GOTO, the Vera C. Rubin Observatory’s LSST, ULTRASAT, VISTA, and WINTER can observe some kilonovae out to z ∼ 0.1 (∼475 Mpc), while DDOTI, MeerLICHT, PRIME, Swift/UVOT, and ZTF are confined to more nearby observations. Furthermore, we provide a framework to infer kilonova ejecta properties following nondetections and explore variation in detectability with these ejecta parameters.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1975

Three-dimensional time dependent computation of turbulent flow

The three-dimensional, primitive equations of motion are solved numerically for the case of isotropic box turbulence and the distortion of homogeneous turbulence by irrotational plane strain at large Reynolds numbers. A Gaussian filter is applied to governing equations to define the large scale field. This gives rise to additional second order computed scale stresses (Leonard stresses). The residual stresses are simulated through an eddy viscosity. Uniform grids are used, with a fourth order differencing scheme in space and a second order Adams-Bashforth predictor for explicit time stepping. The results are compared to the experiments and statistical information extracted from the computer generated data.

Kwak, D.↗
NASA NTRS1978

Investigation of models for large-scale meteorological prediction experiments

The feasibility of long-range weather prediction through the use of global general circulation models (GCMs) was investigated. A climate model was developed to simulate the monthly mean state of the atmosphere from real global initial data at the beginning of the month. The model contains the same dynamic and physical ingredients as most numerical weather prediction models and GCMs. The model generates a one-day global simulation on the 8 x 10 grid in four minutes (on an IBM 360/95 computer), so that a 30 day forecast can be executed in two hours. The high speed of the model is achieved mainly at the price of its coarse resolution, which requires certain parameterizations of surface boundary conditions, as well as inherent filtering of smaller-scale features of the initial state.

Spar, J.↗
NASA NTRS1984

Effects of very high turbulence on convective heat transfer

The effects of high-intensity, large-scale turbulence on turbulent boundary-layer heat transfer are studied. Flow fields were produced with turbulence intensities up to 40% and length scales up to several times the boundary layer thickness. In addition, three different types of turbulence will be compared to see whether they have the same effect on the boundary layer. The three are: the far field of a free jet, flow downstream of a grid, and flow downstream of a simulated gas turbine combustor. Each turbulence field will be characterized by several measures: intensity (by component), scale, and spectrum. Heat transfer will be measured on a 2.5 m long, 0.5 m wide flat plate using the energy-balance technique. The same plate will be used in each of the four flow fields; a low-turbulence tunnel for baseline data, and the three flow situations mentioned.

Moffat, R. J.↗
NASA NTRS1987

Numerical simulation of compressible flow around complex two-dimensional cavities

Compressible viscous flow around two-dimensional cavities, that model the midplane flow in and around an airborne telescope cavity, are obtained through numerical simulation. Numerical solutions using the patched grid CSCM scheme for compressible, unsteady flow are presented for the cavities, with and without blowing. The time evolving solutions show interesting flow features. Relevant results for a limited number of problems presented here show the unsteady nature of the flow and its dependence on various parameters such as Reynolds number, the wall conditions, etc. The voluminous data of time evolving flow field solutions are analyzed through movies of the velocity vectors, and contours of other flow variables.

Venkatapathy, Ethiraj↗
NASA NTRS1991

Cost-effective accurate coarse-grid method for highly convective multidimensional unsteady flows

A fundamentally multidimensional convection scheme is described based on vector transient interpolation modeling rewritten in conservative control-volume form. Vector third-order upwinding is used as the basis of the algorithm; this automatically introduces important cross-difference terms that are absent from schemes using component-wise one-dimensional formulas. Third-order phase accuracy is good; this is important for coarse-grid large-eddy or full simulation. Potential overshoots or undershoots are avoided by using a recently developed universal limiter. Higher order accuracy is obtained locally, where needed, by the cost-effective strategy of adaptive stencil expansion in a direction normal to each control-volume face; this is controlled by monitoring the absolute normal gradient and curvature across the face. Higher (than third) order cross-terms do not appear to be needed. Since the wider stencil is used only in isolated narrow regions (near discontinuities), extremely high (in this case, seventh) order accuracy can be achieved for little more than the cost of a globally third-order scheme.

Leonard, B. P.↗
NASA NTRS1992

Numerical methods for the simulation of complex multi-body flows with applications for the integrated Space Shuttle vehicle

This project forms part of the long term computational effort to simulate the time dependent flow over the integrated Space Shuttle vehicle (orbiter, solid rocket boosters (SRB's), external tank (ET), and attach hardware) during its ascent mode for various nominal and abort flight conditions. Due to the limitations of experimental data such as wind tunnel wall effects and the difficulty of safely obtaining valid flight data, numerical simulations are undertaken to supplement the existing data base. This data can then be used to predict the aerodynamic behavior over a wide range of flight conditions. Existing computational results show relatively good overall comparison with experiments but further refinement is required to reduce numerical errors and to obtain finer agreements over a larger parameter space. One of the important goals of this project is to obtain better comparisons between numerical simulations and experiments. In the simulations performed so far, the geometry has been simplified in various ways to reduce the complexity so that useful results can be obtained in a reasonable time frame due to limitations in computer resources. In this project, the finer details of the major components of the Space Shuttle are modeled better by including more complexity in the geometry definition. Smaller components not included in early Space Shuttle simulations will now be modeled and gridded.

Chan, William M.↗
NASA NTRS1991

Multidisciplinary modeling and simulation of a generic hypersonic vehicle

The modeling and simulation of hypersonic vehicles which involve the interaction of a number of major technical disciplines including aerodynamics, structures, heat transfer, propulsion, and control engineering are described. Finite element numerical formulations of individual disciplines including their appropriate integration for multidisciplinary simulation are presented. An efficient unstructured grid generation strategy, evolved by modifying an existing code, is developed.

Gupta, K. K.↗
NASA NTRS1993

Numerical simulation of three-dimensional self-gravitating flow

The three-dimensional flow of a self-gravitating fluid is numerically simulated using a Fourier pseudospectral method with a logarithmic variable formulation. Two cases with zero total angular momentum are studied in detail, a 323 simulation (Run B). Other than the grid size, the primary difference between the two cases are that Run A modeled atomic hydrogen and had considerably more compressible motion initially than Run B, which modeled molecular hydrogen. The numerical results indicate that gravitational collapse can proceed in a variety of ways. In the Run A, collapse led to an elongated tube-like structure, while in the Run B, collapse led to a flatter, disklike structure.

Shebalin, John V.↗