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Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

Description: The TSTC project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of our approach is direct numerical simulation (DNS) featuring highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level si… more
Date: February 2, 2009
Creator: Im, Hong G.; Trouve, Arnaud; Rutland, Christopher J. & Chen, Jacqueline H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Extended model for Richtmyer-Meshkov mix

Description: We examine four Richtmyer-Meshkov (RM) experiments on shock-generated turbulent mix and find them to be in good agreement with our earlier simple model in which the growth rate h of the mixing layer following a shock or reshock is constant and given by 2{alpha}A{Delta}v, independent of initial conditions h{sub 0}. Here A is the Atwood number ({rho}{sub B}-{rho}{sub A})/({rho}{sub B} + {rho}{sub A}), {rho}{sub A,B} are the densities of the two fluids, {Delta}V is the jump in velocity induced by … more
Date: November 18, 2009
Creator: Mikaelian, K O
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Plasma Simulation Using Gyrokinetic-Gyrofluid Hybrid Models

Description: We are developing kinetic ion models for the simulation of extended MHD phenomena. The model they have developed uses full Lorentz force ions, and either drift-kinetic or gyro-kinetic electrons. Quasi-neutrality is assumed and the displacement current is neglected. They are also studying alpha particle driven Toroidal Alfven Eigenmodes (TAE) in the GEM gyrokinetic code [Chen 07]. The basic kinetic ion MHD model was recently reported in an invited talk given by Dan Barnes at the 2007 American Ph… more
Date: April 9, 2009
Creator: Parker, Scott
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Statistics of particle concentration in free-surface turbulence

Description: Particles on the surface of an incompressible fluid maintained in a turbulent steady-state cluster into spatio-temporally complex flow structures. We experimentally study the statistics of particle concentration n(r, t) over various coarse-grained scales r' in the inertial range. Another control parameter is the Taylor Microscale Reynolds number Re{sub {lambda}}. The focus is on the steady state probability density function {Pi}(n{sub r}). Attention is also given to the variance {sigma}{sup 2}(… more
Date: January 1, 2009
Creator: Bandi, Mahesh M; Larkin, J & Goldburg, W
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Plasma Equilibrium in a Magnetic Field with Stochastic Regions

Description: The nature of plasma equilibrium in a magnetic field with stochastic regions is examined. It is shown that the magnetic differential equation that determines the equilibrium Pfirsch-Schluter currents can be cast in a form similar to various nonlinear equations for a turbulent plasma, allowing application of the mathematical methods of statistical turbulence theory. An analytically tractable model, previously studied in the context of resonance-broadening theory, is applied with particular atten… more
Date: April 23, 2009
Creator: Reiman, J.A. Krommes and Allan H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Sherwood/APS 2006 Conference

Description: The International Sherwood Theory Meeting is a yearly meeting that focuses on the theory of magnetically confined fusion plasmas. There are many topics of common interest in fusion plasma systems and space and astrophysical plasmas. These common topics include such key topics as magnetic reconnection, the dynamo, turbulence and transport and particle heating and acceleration. One of the major participants of the April APS meeting is the APS Division of Astrophysics (DAP). The goal of having the… more
Date: July 28, 2009
Creator: Drake, James F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Computational Fluid Dynamic Analysis of the VHTR Lower Plenum Standard Problem

Description: The United States Department of Energy is promoting the resurgence of nuclear power in the U. S. for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The DOE project is called the next generation nuclear plant (NGNP) and is based on a Generation IV reactor concept called the very high temperature reactor (VHTR), which will use helium as the coolant at temperatures ranging from … more
Date: July 1, 2009
Creator: Johnson, Richard W. & Schultz, Richard R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Astrophysical Gyrokinetics: Kinetic and Fluid Turbulent Cascades In Magentized Weakly Collisional Plasmas

Description: This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulentmotions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are … more
Date: April 23, 2009
Creator: A.A. Schekochihin, S.C. Cowley, W. Dorland, G.W. Hammett, G.G. Howes, E. Quataert, and T. Tatsuno
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames

Description: This paper presents topology-based methods to robustly extract, analyze, and track features defined as subsets of isosurfaces. First, we demonstrate how features identified by thresholding isosurfaces can be defined in terms of the Morse complex. Second, we present a specialized hierarchy that encodes the feature segmentation independent of the threshold while still providing a flexible multi-resolution representation. Third, for a given parameter selection we create detailed tracking graphs re… more
Date: June 1, 2009
Creator: Bremer, Peer-Timo; Weber, Gunther; Pascucci, Valerio; Day, Marc & Bell, John
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Electron Gyro-scale Fluctuation Measurements in National Spherical Torus Experiment H-mode Plasmas

Description: A collective scattering system has measured electron gyro-scale fluctuations in National Spherical Torus Experiment (NSTX) H-mode plasmas to investigate electron temperature gradient (ETG) turbulence. Observations and results pertaining to fluctuation measurements in ETGstable regimes, the toroidal field scaling of fluctuation amplitudes, the relation between between fluctuation amplitudes and transport quantities, and fluctuation magnitudes and k-spectra are presented. Collectively, the measur… more
Date: August 10, 2009
Creator: Smith, D. R.; Lee, W.; Mazzucato, E.; Park, H. K.; Bell, R. E.; Domier, C. W. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Comment on Turbulent Equipartition Theory of Toroidal Momentum Pinch

Description: This response demonstrates that the comment by Peeters et al. contains an incorrect and misleading interpretation of our paper [Hahm et al., Phys. Plasmas 15, 055902 (2008)] regarding the density gradient dependence of momentum pinch and the turbulent equipartition (TEP) theory.
Date: March 12, 2009
Creator: T.S. Hahm, P.H. Diamond, O.D. Gurcan, and G. Rewoldt
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Momentum Transport in Electron-Dominated Spherical Torus Plasmas

Description: The National Spherical Torus Experiment (NSTX) operates between 0.35 and 0.55 T, which, when coupled to up to 7 MW of neutral beam injection, leads to central rotation velocities in excess of 300 km/s and ExB shearing rates up to 1 MHz. This level of ExB shear can be up to a factor of five greater than typical linear growth rates of long-wavelength ion (e.g., ITG) modes, at least partially suppressing these instabilities. Evidence for this turbulence suppression is that the inferred diffusive i… more
Date: February 24, 2009
Creator: Kaye, S. M.; Solomon, W.; Bell, R. E.; LeBlanc, B. P.; Levinton, F.; Menard, J. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Computational Fluid Dynamics Analyses on Very High Temperature Reactor Air Ingress

Description: A preliminary computational fluid dynamics (CFD) analysis was performed to understand density-gradient-induced stratified flow in a Very High Temperature Reactor (VHTR) air-ingress accident. Various parameters were taken into consideration, including turbulence model, core temperature, initial air mole-fraction, and flow resistance in the core. The gas turbine modular helium reactor (GT-MHR) 600 MWt was selected as the reference reactor and it was simplified to be 2-D geometry in modeling. The … more
Date: July 1, 2009
Creator: Oh, Chang H; Kim, Eung S.; Schultz, Richard; Petti, David & Kang, Hyung S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Joint physical and numerical modeling of water distribution networks.

Description: This report summarizes the experimental and modeling effort undertaken to understand solute mixing in a water distribution network conducted during the last year of a 3-year project. The experimental effort involves measurement of extent of mixing within different configurations of pipe networks, measurement of dynamic mixing in a single mixing tank, and measurement of dynamic solute mixing in a combined network-tank configuration. High resolution analysis of turbulence mixing is carried out vi… more
Date: January 1, 2009
Creator: Zimmerman, Adam; O'Hern, Timothy John; Orear, Leslie Jr.; Kajder, Karen C.; Webb, Stephen Walter; Cappelle, Malynda A. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Geometry Dependence of Stellarator Turbulence

Description: Using the nonlinear gyrokinetic code package GENE/GIST, we study the turbulent transport in a broad family of stellarator designs, to understand the geometry-dependence of the microturbulence. By using a set of flux tubes on a given flux surface, we construct a picture of the 2D structure of the microturbulence over that surface, and relate this to relevant geometric quantities, such as the curvature, local shear, and effective potential in the Schrodinger-like equation governing linear drift m… more
Date: August 10, 2009
Creator: H.E. Mynick, P. Xanthopoulos and A.H. Boozer
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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EXAMINATION OF A PROPOSED VALIDATION DATA SET USING CFD CALCULATIONS

Description: The United States Department of Energy is promoting the resurgence of nuclear power in the U. S. for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The DOE project is called the next generation nuclear plant (NGNP) and is based on a Generation IV reactor concept called the very high temperature reactor (VHTR), which will use helium as the coolant at temperatures ranging from … more
Date: August 1, 2009
Creator: Johnson, Richard W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Studies of Flows in Plasmas

Description: Note a pdf document "DOE-flow-final-report' should be attached. If it somehow is not please notify Walter Gekelman (gekelman@physics.ucla.edu) who will e mail it directly
Date: March 7, 2009
Creator: Gekelman, Walter; Morales, George & Maggs, James
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Study of Turbulent Fluctuations Driven by the Electron Temperature Gradient in the National Spherical Torus Experiment

Description: Various theories and numerical simulations support the conjecture that the ubiquitous problem of anomalous electron transport in tokamaks may arise from a short-scale turbulence driven by the electron temperature gradient. To check whether this turbulence is present in plasmas of the National Spherical Torus Experiment (NSTX), measurements of turbulent fluctuations were performed with coherent scattering of electromagnetic waves. Results from plasmas heated by high harmonic fast waves (HHFW) sh… more
Date: March 26, 2009
Creator: Mazzucato, E.; Bell, R. E.; Ethier, S.; Hosea, J. C.; Kaye, S. M.; LeBlanc, B. P. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Comparison of Scrape-off Layer Turbulence in Alcator C-Mod with Three Dimensional Gyrofluid Computations

Description: This paper describes quantitative comparisons between turbulence measured in the scrape-off layer (SOL) of Alcator C-Mod [S. Scott, A. Bader, M. Bakhtiari et al., Nucl. Fusion 47, S598 (2007)] and three dimensional computations using electromagnetic gyrofluid equations in a two-dimensional tokamak geometry. These comparisons were made for the outer midplane SOL for a set of inner-wall limited, near-circular Ohmic plasmas. The B field and plasma density were varied to assess gyroradius and colli… more
Date: September 1, 2009
Creator: S.J. Zweben, B.D. Scott, J.L. Terry, B. LaBombard, J.W. Hughes, and D.P. Stotler
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Theory of Fine-scale Zonal Flow Generation From Trapped Electron Mode Turbulence

Description: Most existing zonal flow generation theory has been developed with a usual assumption of qrρθ¡ << 1 (qr is the radial wave number of zonal flow, and ρθ¡ is the ion poloidal gyrora- dius). However, recent nonlinear gyrokinetic simulations of trapped electron mode (TEM) turbulence exhibit a relatively short radial scale of the zonal flows with qrρθ¡ ~ 1 [Z. Lin et al., IAEA-CN/TH/P2-8 (2006); D. Ernst et al., Phys. Plasmas 16, 055906 (2009)]. This work reports an extension of zonal flow growth ca… more
Date: June 11, 2009
Creator: Hahm, Lu Wang and T.S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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