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14, 484 p. 23 cm

14, 484 p. 23 cm

14, 484 p. 23 cm

The goal of this project has been to advance the state-of-the-art in performing fluid-structure interaction (FSI) simulations of parachute systems. This capability is being used by the Army to evaluate the dynamic behavior of new and existing airdrop systems. Airdrop systems have traditionally been designed using semi-empirical methods supplemented by extensive testing, which is time consuming and expensive. Computer simulation provides a cost effective alternative to this approach. FSI simulations of airdrop systems require coupling of computational structural and fluid dynamics models. These simulations are very computationally intensive and therefore parallel computational methods are essential. Specifics objectives addressed under this project focused on both the structural mechanics and parallel requirements; the required fluid dynamics component has been performed collaboratively at Rice University under a separate effort. The project accomplishments are classified into the following three general areas that are described in detail in this report: 1. Development of parallel structural algorithms required for FSI simulations 2. Development of new structural mechanics theory for modeling airdrop systems 3. Performance of large-scale computer simulations of Army airdrop systems

The goal of this project has been to advance the state-of-the-art in performing fluid-structure interaction (FSI) simulations of parachute systems. This capability is being used by the Army to evaluate the dynamic behavior of new and existing airdrop systems. Airdrop systems have traditionally been designed using semi-empirical methods supplemented by extensive testing, which is time consuming and expensive. Computer simulation provides a cost effective alternative to this approach. FSI simulations of airdrop systems require coupling of computational structural and fluid dynamics models. These simulations are very computationally intensive and therefore parallel computational methods are essential. Specifics objectives addressed under this project focused on both the structural mechanics and parallel requirements; the required fluid dynamics component has been performed collaboratively at Rice University under a separate effort. The project accomplishments are classified into the following three general areas that are described in detail in this report: 1. Development of parallel structural algorithms required for FSI simulations 2. Development of new structural mechanics theory for modeling airdrop systems 3. Performance of large-scale computer simulations of Army airdrop systems

The Two-phase Flow, Fluid Stability and Dynamics Workshop was held on May 15, 2003 in Cleveland, Ohio to define a coherent scientific research plan and roadmap that addresses the multiphase fluid problems associated with NASA s technology development program. The workshop participants, from academia, industry and government, prioritized various multiphase issues and generated a research plan and roadmap to resolve them. This report presents a prioritization of the various multiphase flow and fluid stability phenomena related primarily to power, propulsion, fluid and thermal management and advanced life support; and a plan to address these issues in a logical and timely fashion using analysis, ground-based and space-flight experiments.

The Two-phase Flow, Fluid Stability and Dynamics Workshop was held on May 15, 2003 in Cleveland, Ohio to define a coherent scientific research plan and roadmap that addresses the multiphase fluid problems associated with NASA s technology development program. The workshop participants, from academia, industry and government, prioritized various multiphase issues and generated a research plan and roadmap to resolve them. This report presents a prioritization of the various multiphase flow and fluid stability phenomena related primarily to power, propulsion, fluid and thermal management and advanced life support; and a plan to address these issues in a logical and timely fashion using analysis, ground-based and space-flight experiments.

x, 308 p. 23 cm

Book digitized by Google from the library of the University of Michigan and uploaded to the Internet Archive by user tpb.

Book digitized by Google from the library of the University of Michigan and uploaded to the Internet Archive by user tpb.

This item represents a case in PACER, the U.S. Government's website for federal case data. If you wish to see the entire case, please consult PACER directly.

The NASA Glenn Research Center, the U.S. Department of Energy, and the Stirling Technology Company (STC) are developing a highly efficient, long-life, free-piston Stirling convertor for use as an advanced spacecraft power system for future NASA missions, including deep-space and Mars surface applications. As part of this development, four structural dynamic test programs were recently performed on Stirling Technology Demonstration Convertors (TDC's) that were designed and built by STC under contract to the Department of Energy. This testing was performed in Glenn's Structural Dynamics Laboratory and Microgravity Emissions Laboratory. The first test program, in November and December 1999, demonstrated that the Stirling TDC could withstand the harsh random vibration experienced during a typical spacecraft launch and survive with no structural damage or functional power performance degradation. This was a critical step in enabling the use of Stirling convertors for future spacecraft power systems. The most severe test was a 12.3grms random vibration test, with test durations of 3 min per axis. The random vibration test levels were chosen to simulate, with margin, the maximum anticipated launch vibration conditions. The Microgravity Emissions Laboratory is typically used to measure the dynamics produced by operating space experiments and the resulting impact to the International Space Station's microgravity environment. For the second Stirling dynamic test program, performed in January 2001, the Microgravity Emissions Laboratory was used to characterize the structure-borne disturbances produced by the normal operation of a pair of Stirling convertors. The forces and moments produced by the normal operation of a Stirling system must be recognized and controlled, if necessary, so that other nearby spacecraft components, such as cameras, are not adversely affected. The Stirling convertor pair emitted relatively benign tonal forces at its operational frequency and associated harmonics. Therefore, Stirling power systems will not disturb spacecraft science experiments if minimal appropriate mounting efforts are made. The third test program, performed in February and May 2001, resulted in a modal characterization of a Stirling convertor. Since the deflection of the TDC piston rod, under vibration excitation, was of particular interest, the outer pressure shell was removed to allow access to the rod. Through this testing, the Stirling TDC's natural frequencies and modes were identified. This knowledge advanced our understanding of the successful 1999 vibration test and may be utilized to optimize the output power of future Stirling designs. The fourth test program, in April 2001, was conducted to characterize the structural response of a pair of Stirling convertors, as a function of their mounting interface stiffness. The test results provide guidance for the Stirling power package interface design. Properly designed, the interface may lead to increased structural capability and power performance beyond what was demonstrated in the successful 1999 vibration test. Dynamic testing performed to date at Glenn has shown that the Stirling convertors can withstand liftoff random vibration environments and meet "good neighbor" vibratory emission requirements. Furthermore, the future utilization of the information obtained during the tests will allow the corporation selected to be the Stirling system integrator to optimize their convertor and system interfaces designs. Glenn's Thermo-Mechanical Systems Branch provides Stirling technology expertise under a Space Act Agreement with the Department of Energy. Additional vibration testing by Glenn's Structural Systems Dynamics Branch is planned to continue to demonstrate the Stirling power system's vibration capability as its technology and flight system designs progress.

The report summarizes the advanced design program in the mechanical engineering department at Vanderbilt University for the academic years 1994-1995 and 1995-1996. Approximately 100 students participated in the two years of the subject grant funding. The NASA-oriented design projects that were selected included lightweight hydrogen propellant tank for the reusable launch vehicle, a thermal barrier coating test facility, a piezoelectric motor for space antenna control, and a lightweight satellite for automated materials processing. The NASA supported advanced design program (ADP) has been a success and a number of graduates are working in aerospace and are doing design.

The report summarizes the advanced design program in the mechanical engineering department at Vanderbilt University for the academic years 1994-1995 and 1995-1996. Approximately 100 students participated in the two years of the subject grant funding. The NASA-oriented design projects that were selected included lightweight hydrogen propellant tank for the reusable launch vehicle, a thermal barrier coating test facility, a piezoelectric motor for space antenna control, and a lightweight satellite for automated materials processing. The NASA supported advanced design program (ADP) has been a success and a number of graduates are working in aerospace and are doing design.

Because of the inherent nonlinearity, most �uid-dynamical problems must be solved by either analytical approximations or by numerical computations. In this chapter we shall �rs texplain the lubrication approximation, with applications to the �ow of thin layers. Attention will then be turned to the slow �ow past a sphere and a cylinder. Application to the environmental problem of aerols will be brie�y discussed. Lastly the slow withdrawal of �uid from a straiti�ed reservoir into a sink will be analyzed.

Because of the inherent nonlinearity, most �uid-dynamical problems must be solved by either analytical approximations or by numerical computations. In this chapter we shall �rs texplain the lubrication approximation, with applications to the �ow of thin layers. Attention will then be turned to the slow �ow past a sphere and a cylinder. Application to the environmental problem of aerols will be brie�y discussed. Lastly the slow withdrawal of �uid from a straiti�ed reservoir into a sink will be analyzed.

This item represents a case in PACER, the U.S. Government's website for federal case data. If you wish to see the entire case, please consult PACER directly.

xi,431p. :

Computational gas dynamics has become a prominent research field both in astrophysics and cosmology. In the first part of this review we intend to briefly describe several of the numerical methods used in this field, discuss their range of application and present strategies for converting conditionally-stable numerical methods into unconditionally-stable solution procedures. The underlying aim of the conversion is to enhance the robustness and unification of numerical methods and subsequently enlarge their range of applications considerably. In the second part Fabian Heitsch presents and discusses the implementation of a time-explicit MHD Boltzmann solver.

Computational gas dynamics has become a prominent research field both in astrophysics and cosmology. In the first part of this review we intend to briefly describe several of the numerical methods used in this field, discuss their range of application and present strategies for converting conditionally-stable numerical methods into unconditionally-stable solution procedures. The underlying aim of the conversion is to enhance the robustness and unification of numerical methods and subsequently enlarge their range of applications considerably. In the second part Fabian Heitsch presents and discusses the implementation of a time-explicit MHD Boltzmann solver.

Computational gas dynamics has become a prominent research field both in astrophysics and cosmology. In the first part of this review we intend to briefly describe several of the numerical methods used in this field, discuss their range of application and present strategies for converting conditionally-stable numerical methods into unconditionally-stable solution procedures. The underlying aim of the conversion is to enhance the robustness and unification of numerical methods and subsequently enlarge their range of applications considerably. In the second part Fabian Heitsch presents and discusses the implementation of a time-explicit MHD Boltzmann solver.

This report evaluates both the hardware and software of the Texas Instruments Advanced Scientific Computer (TIASC) at the Naval Research Laboratory in terms of their applicability to numerical fluid dynamics calculations. DTNSRDC users access this computer via an on-site Remote Job Entry Terminal. The 'pipelined' central processor of the TIASC has been found particularly valuable in numerical fluid dynamics work, especially when combined with the graphics capabilities available at DTNSRDC. Several examples of fluid dynamics problems which were successfully solved using the TIASC are given. (Author)

This report evaluates both the hardware and software of the Texas Instruments Advanced Scientific Computer (TIASC) at the Naval Research Laboratory in terms of their applicability to numerical fluid dynamics calculations. DTNSRDC users access this computer via an on-site Remote Job Entry Terminal. The 'pipelined' central processor of the TIASC has been found particularly valuable in numerical fluid dynamics work, especially when combined with the graphics capabilities available at DTNSRDC. Several examples of fluid dynamics problems which were successfully solved using the TIASC are given. (Author)

285 p. 24 cm

With a general pressure gradient the boundary layer equations can be solved by a variety of modern numerical means. An alternative which can still be employed to simplify calculations is the momentum integral method of Karman. We explain this method for a transient boundary layer along the x-axis forced by an unsteady pressure gradient outside. This pressure gradient can be due to some unsteady and nonuniform �ow such as waves or gust.

With a general pressure gradient the boundary layer equations can be solved by a variety of modern numerical means. An alternative which can still be employed to simplify calculations is the momentum integral method of Karman. We explain this method for a transient boundary layer along the x-axis forced by an unsteady pressure gradient outside. This pressure gradient can be due to some unsteady and nonuniform �ow such as waves or gust.

With a general pressure gradient the boundary layer equations can be solved by a variety of modern numerical means. An alternative which can still be employed to simplify calculations is the momentum integral method of Karman. We explain this method for a transient boundary layer along the x-axis forced by an unsteady pressure gradient outside. This pressure gradient can be due to some unsteady and nonuniform �ow such as waves or gust.

Long term, climatologically significant statistical properties of the atmospheric component of the climate system are examined in an effort to correctly and efficiently incorporate this component into larger models for climate that include oceanic and cryospheric influences and deal realistically with climate replication. The magnetic of the unpredictable (noise) component of long term atmospheric behavior is also studied in order to develop the potential for viable climatological forecasting.

A general presentation of DNA structure, followed by presentation of advanced techniques for DNA studies of structure and dynamics by various contributors.

A general presentation of DNA structure, followed by presentation of advanced techniques for DNA studies of structure and dynamics by various contributors.

-an experimental and computational study of the fluid dynamics of dense cooling air-mists; direct numerical simulations of compressible vortex flow problems; fluid dynamics of gas-solid fluidized beds; fuel jet in cross flow-experimental study of spray characteristics; influence of horizontal temperature gradients on convective instabilities with geophysical interest; internal flows driven by wall-normal injection; modelling of turbulent premixed and partially premixed combustion; multiscale window interaction and localized nonlinear hydrodynamic stability analysis; stability investigation of combustion chambers with LES; turbulent boundary layer models-theory and applications; unitary qubit lattice gas representation of 2d and 3d quantum turbulence-

-an experimental and computational study of the fluid dynamics of dense cooling air-mists; direct numerical simulations of compressible vortex flow problems; fluid dynamics of gas-solid fluidized beds; fuel jet in cross flow-experimental study of spray characteristics; influence of horizontal temperature gradients on convective instabilities with geophysical interest; internal flows driven by wall-normal injection; modelling of turbulent premixed and partially premixed combustion; multiscale window interaction and localized nonlinear hydrodynamic stability analysis; stability investigation of combustion chambers with LES; turbulent boundary layer models-theory and applications; unitary qubit lattice gas representation of 2d and 3d quantum turbulence-

Book digitized by Google and uploaded to the Internet Archive by user tpb.

Book digitized by Google and uploaded to the Internet Archive by user tpb.

Book digitized by Google and uploaded to the Internet Archive by user tpb.

Book digitized by Google and uploaded to the Internet Archive by user tpb.

Book digitized by Google and uploaded to the Internet Archive by user tpb.

Book digitized by Google and uploaded to the Internet Archive by user tpb.

Book digitized by Google and uploaded to the Internet Archive by user tpb.

We analyze heartbeat interval recordings from two independent databases: (a) 19 healthy young (avg. age 25.7 years) and 16 healthy elderly subjects (avg. age 73.8 years) during 2h under resting conditions from the Fantasia database; and (b) 29 healthy elderly subjects (avg. age 75.9 years) during $\approx{}8$h of sleep from the SHHS database, and the same subjects recorded 5 years later. We quantify: (1) The average heart rate ; (2) the SD $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ of the heartbeat intervals RR and their increments $\Delta{}RR$; (3) the long-range correlations in RR as measured by the scaling exponent $\alpha_{RR}$ using the Detrended Fluctuation Analysis; (4) fractal linear and nonlinear properties as represented by the scaling exponents $\alpha^{sign}$ and $\alpha^{mag}$ for the time series of the sign and magnitude of $\Delta{}RR$; (5) the nonlinear fractal dimension $D(k)$ of $RR$ using the Fractal Dimension Analysis. We find: (1) No significant difference in $\left$ (P>0.05); (2) a significant difference in $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ for the Fantasia groups (P 0.5); (3) no significant change in the fractal measures $\alpha_{RR}$ (P>0.15), $\alpha^{sign}$ (P>0.2), $\alpha^{mag}$ (P>0.3), and D(k) with age. Our findings do not support the hypothesis that fractal linear and nonlinear characteristics of heartbeat dynamics break down with advanced age in healthy subjects. While our results indeed show a reduced SD of heartbeat fluctuations with advanced age, the inherent temporal fractal and nonlinear organization of these fluctuations remains stable.

We analyze heartbeat interval recordings from two independent databases: (a) 19 healthy young (avg. age 25.7 years) and 16 healthy elderly subjects (avg. age 73.8 years) during 2h under resting conditions from the Fantasia database; and (b) 29 healthy elderly subjects (avg. age 75.9 years) during $\approx{}8$h of sleep from the SHHS database, and the same subjects recorded 5 years later. We quantify: (1) The average heart rate ; (2) the SD $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ of the heartbeat intervals RR and their increments $\Delta{}RR$; (3) the long-range correlations in RR as measured by the scaling exponent $\alpha_{RR}$ using the Detrended Fluctuation Analysis; (4) fractal linear and nonlinear properties as represented by the scaling exponents $\alpha^{sign}$ and $\alpha^{mag}$ for the time series of the sign and magnitude of $\Delta{}RR$; (5) the nonlinear fractal dimension $D(k)$ of $RR$ using the Fractal Dimension Analysis. We find: (1) No significant difference in $\left$ (P>0.05); (2) a significant difference in $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ for the Fantasia groups (P 0.5); (3) no significant change in the fractal measures $\alpha_{RR}$ (P>0.15), $\alpha^{sign}$ (P>0.2), $\alpha^{mag}$ (P>0.3), and D(k) with age. Our findings do not support the hypothesis that fractal linear and nonlinear characteristics of heartbeat dynamics break down with advanced age in healthy subjects. While our results indeed show a reduced SD of heartbeat fluctuations with advanced age, the inherent temporal fractal and nonlinear organization of these fluctuations remains stable.

We analyze heartbeat interval recordings from two independent databases: (a) 19 healthy young (avg. age 25.7 years) and 16 healthy elderly subjects (avg. age 73.8 years) during 2h under resting conditions from the Fantasia database; and (b) 29 healthy elderly subjects (avg. age 75.9 years) during $\approx{}8$h of sleep from the SHHS database, and the same subjects recorded 5 years later. We quantify: (1) The average heart rate ; (2) the SD $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ of the heartbeat intervals RR and their increments $\Delta{}RR$; (3) the long-range correlations in RR as measured by the scaling exponent $\alpha_{RR}$ using the Detrended Fluctuation Analysis; (4) fractal linear and nonlinear properties as represented by the scaling exponents $\alpha^{sign}$ and $\alpha^{mag}$ for the time series of the sign and magnitude of $\Delta{}RR$; (5) the nonlinear fractal dimension $D(k)$ of $RR$ using the Fractal Dimension Analysis. We find: (1) No significant difference in $\left$ (P>0.05); (2) a significant difference in $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ for the Fantasia groups (P 0.5); (3) no significant change in the fractal measures $\alpha_{RR}$ (P>0.15), $\alpha^{sign}$ (P>0.2), $\alpha^{mag}$ (P>0.3), and D(k) with age. Our findings do not support the hypothesis that fractal linear and nonlinear characteristics of heartbeat dynamics break down with advanced age in healthy subjects. While our results indeed show a reduced SD of heartbeat fluctuations with advanced age, the inherent temporal fractal and nonlinear organization of these fluctuations remains stable.

We analyze heartbeat interval recordings from two independent databases: (a) 19 healthy young (avg. age 25.7 years) and 16 healthy elderly subjects (avg. age 73.8 years) during 2h under resting conditions from the Fantasia database; and (b) 29 healthy elderly subjects (avg. age 75.9 years) during $\approx{}8$h of sleep from the SHHS database, and the same subjects recorded 5 years later. We quantify: (1) The average heart rate ; (2) the SD $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ of the heartbeat intervals RR and their increments $\Delta{}RR$; (3) the long-range correlations in RR as measured by the scaling exponent $\alpha_{RR}$ using the Detrended Fluctuation Analysis; (4) fractal linear and nonlinear properties as represented by the scaling exponents $\alpha^{sign}$ and $\alpha^{mag}$ for the time series of the sign and magnitude of $\Delta{}RR$; (5) the nonlinear fractal dimension $D(k)$ of $RR$ using the Fractal Dimension Analysis. We find: (1) No significant difference in $\left$ (P>0.05); (2) a significant difference in $\sigma_{RR}$ and $\sigma_{\Delta{}RR}$ for the Fantasia groups (P 0.5); (3) no significant change in the fractal measures $\alpha_{RR}$ (P>0.15), $\alpha^{sign}$ (P>0.2), $\alpha^{mag}$ (P>0.3), and D(k) with age. Our findings do not support the hypothesis that fractal linear and nonlinear characteristics of heartbeat dynamics break down with advanced age in healthy subjects. While our results indeed show a reduced SD of heartbeat fluctuations with advanced age, the inherent temporal fractal and nonlinear organization of these fluctuations remains stable.

This grant provided for the demonstration of coupled controls, body dynamics, and fluids computations in a workstation cluster environment; and an investigation of the impact of peer-peer communication on flow solver performance and robustness. The findings of these investigations were documented in the conference articles.The attached publication, 'Towards Distributed Fluids/Controls Simulations', documents the solution and scaling of the coupled Navier-Stokes, Euler rigid-body dynamics, and state feedback control equations for a two-dimensional canard-wing. The poor scaling shown was due to serialized grid connectivity computation and Ethernet bandwidth limits. The scaling of a peer-to-peer communication flow code on an IBM SP-2 was also shown. The scaling of the code on the switched fabric-linked nodes was good, with a 2.4 percent loss due to communication of intergrid boundary point information. The code performance on 30 worker nodes was 1.7 (mu)s/point/iteration, or a factor of three over a Cray C-90 head. The attached paper, 'Nonlinear Fluid Computations in a Distributed Environment', documents the effect of several computational rate enhancing methods on convergence. For the cases shown, the highest throughput was achieved using boundary updates at each step, with the manager process performing communication tasks only. Constrained domain decomposition of the implicit fluid equations did not degrade the convergence rate or final solution. The scaling of a coupled body/fluid dynamics problem on an Ethernet-linked cluster was also shown.

The construction of a large test facility has been proposed for simulating the blast and thermal environment resulting from nuclear explosions. This facility would be used to test the survivability and vulnerability of military equipment such as trucks, tanks and helicopters in a simulated thermal and blast environment, and to perform research into nuclear blast phenomenology. The proposed advanced design concepts, heating of driver gas and fast-acting throat valves for wave shaping, are described and the results of CFD studies to advance these new technical concepts fro simulating decaying blast waves are reported. Keywords: Computational fluid dynamics; Large blast wave simulators; Thermal simulators; CFD design studies; Blast wave simulation; LB/TS Design.

The construction of a large test facility has been proposed for simulating the blast and thermal environment resulting from nuclear explosions. This facility would be used to test the survivability and vulnerability of military equipment such as trucks, tanks and helicopters in a simulated thermal and blast environment, and to perform research into nuclear blast phenomenology. The proposed advanced design concepts, heating of driver gas and fast-acting throat valves for wave shaping, are described and the results of CFD studies to advance these new technical concepts fro simulating decaying blast waves are reported. Keywords: Computational fluid dynamics; Large blast wave simulators; Thermal simulators; CFD design studies; Blast wave simulation; LB/TS Design.