Efficient solution of the Euler and Navier-Stokes equations with a vectorized multiple-grid algorithm

A multiple-grid algorithm for use in efficiently obtaining steady solutions to the Euler and Navier-Stokes equations is presented. The convergence of the explicit MacCormack algorithm on a fine grid is accelerated by propagating transients from the domain using a sequence of successively coarser grids. Both the fine and coarse grid schemes are readily vectorizable. The combination of multiple-gridding and vectorization results in substantially reduced computational times for the numerical solution of a wide range of flow problems. Results are presented for subsonic, transonic, and supersonic inviscid flows and for subsonic attached and separated laminar viscous flows. Work reduction factors over a scalar, single-grid algorithm range as high as 76.8

Finite element analysis of inviscid subsonic boattail flow

A finite element code for analysis of inviscid subsonic flows over arbitrary nonlifting planar or axisymmetric bodies is described. The code solves a novel primitive variable formulation of the coupled irrotationality and compressible continuity equations. Results for flow over a cylinder, a sphere, and a NACA 0012 airfoil verify the code. Computed subcritical flows over an axisymmetric boattailed afterbody compare well with finite difference results and experimental data. Interative coupling with an integral turbulent boundary layer code shows strong viscous effects on the inviscid flow. Improvements in code efficiency and extensions to transonic flows are discussed

Axisymmetric Calculations of a Low-Boom Inlet in a Supersonic Wind Tunnel

This paper describes axisymmetric CFD predictions made of a supersonic low-boom inlet with a facility diffuser, cold pipe, and mass flow plug within wind tunnel walls, and compares the CFD calculations with the experimental data. The inlet was designed for use on a small supersonic aircraft that would cruise at Mach 1.6, with a Mach number over the wing of 1.7. The inlet was tested in the 8-ft by 6-ft Supersonic Wind Tunnel at NASA Glenn Research Center in the fall of 2010 to demonstrate the performance and stability of a practical flight design that included a novel bypass duct. The inlet design is discussed here briefly. Prior to the test, CFD calculations were made to predict the performance of the inlet and its associated wind tunnel hardware, and to estimate flow areas needed to throttle the inlet. The calculations were done with the Wind-US CFD code and are described in detail. After the test, comparisons were made between computed and measured shock patterns, total pressure recoveries, and centerline pressures. The results showed that the dual-stream inlet had excellent performance, with capture ratios near one, a peak core total pressure recovery of 96 percent, and a large stable operating range. Predicted core recovery agreed well with the experiment but predicted bypass recovery and maximum capture ratio were high. Calculations of offdesign performance of the inlet along a flight profile agreed well with measurements and previous calculations

The relationship of female physical attractiveness to body fatness

Funding This work was supported by NSFC grant 91431102 from the National Science Foundation of China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Acknowledgements We are grateful to all the participants from all the countries and all the members of Molecular Energetics Group for their help on the investigation and discussion of the results.Peer reviewedPublisher PD

Micro-Ramps for External Compression Low-Boom Inlets

The application of vortex generators for flow control in an external compression, axisymmetric, low-boom concept inlet was investigated using RANS simulations with three-dimensional (3-D), structured, chimera (overset) grids and the WIND-US code. The low-boom inlet design is based on previous scale model 1- by 1-ft wind tunnel tests and features a zero-angle cowl and relaxed isentropic compression centerbody spike, resulting in defocused oblique shocks and a weak terminating normal shock. Validation of the methodology was first performed for micro-ramps in supersonic flow on a flat plate with and without oblique shocks. For the inlet configuration, simulations with several types of vortex generators were conducted for positions both upstream and downstream of the terminating normal shock. The performance parameters included incompressible axisymmetric shape factor, separation area, inlet pressure recovery, and massflow ratio. The design of experiments (DOE) methodology was used to select device size and location, analyze the resulting data, and determine the optimal choice of device geometry. The optimum upstream configuration was found to substantially reduce the post-shock separation area but did not significantly impact recovery at the aerodynamic interface plane (AIP). Downstream device placement allowed for fuller boundary layer velocity profiles and reduced distortion. This resulted in an improved pressure recovery and massflow ratio at the AIP compared to the baseline solid-wall configuration

"My Children and I Will no Longer Suffer from Malaria": A Qualitative Study of the Acceptance and Rejection of Indoor Residual Spraying to Prevent Malaria in Tanzania.

The objective of this study was to identify attitudes and misconceptions related to acceptance or refusal of indoor residual spraying (IRS) in Tanzania for both the general population and among certain groups (e.g., farmers, fishermen, community leaders, and women). This study was a series of qualitative, semi-structured, in-depth interviews and focus group discussions conducted from October 2010 to March 2011 on Mainland Tanzania and Zanzibar. Three groups of participants were targeted: acceptors of IRS (those who have already had their homes sprayed), refusers (those whose communities have been sprayed, but refused to have their individual home sprayed), and those whose houses were about to be sprayed as part of IRS scale-up. Interviews were also conducted with farmers, fishermen, women, community leaders and members of non-government organizations responsible for community mobilization around IRS. Results showed refusers are a very small percentage of the population. They tend to be more knowledgeable people such as teachers, drivers, extension workers, and other civil servants who do not simply follow the orders of the local government or the sprayers, but are skeptical about the process until they see true results. Refusal took three forms: 1) refusing partially until thorough explanation is provided; 2) accepting spray to be done in a few rooms only; and 3) refusing outright. In most of the refusal interviews, refusers justified why their houses were not sprayed, often without admitting that they had refused. Reasons for refusal included initial ignorance about the reasons for IRS, uncertainty about its effectiveness, increased prevalence of other insects, potential physical side effects, odour, rumours about the chemical affecting fertility, embarrassment about moving poor quality possessions out of the house, and belief that the spray was politically motivated. To increase IRS acceptance, participants recommended more emphasis on providing thorough public education, ensuring the sprayers themselves are more knowledgeable about IRS, and asking that community leaders encourage participation by their constituents rather than threatening punishment for noncompliance. While there are several rumours and misconceptions concerning IRS in Tanzania, acceptance is very high and continues to increase as positive results become apparent

Supply-Chain Management Issues In The Oil And Gas Industry

The oil and gas industry is involved in a global supply-chain that includes domestic and international transportation, ordering  and inventory visibility and control, materials handling, import/export facilitation and information technology. Thus, the industry offers a classic model for implementing supply-chain management techniques. In a supply-chain, a company is linked to its upstream suppliers and downstream distributors as materials, information, and capital flow through the supply-chain.  The purpose of this paper is to investigate the role of supply-chain management in the oil and gas industry. This paper also discusses the application of the Uniform Commercial Code (UCC) to supply-chain management issues. Then, several strategies are examined for improving supply-chains in the oil and gas industry. Finally, two case studies are introduced to show how improving supply-chain logistics in the oil and gas industry can improve efficiency and the bottom line

Intensity Of Energy Use In The U.S.A.: 1949 - 2003

The particular role that energy plays in the economy of a country, and the relationship between energy consumption and economic growth are of interest to researchers, analysts, and policymakers. Energy consumption can be seen as either a cause of, or a symptom of economic growth. Therefore, understanding the nature of the interactions between energy consumption and gross domestic product (GDP) can help guide energy policies. This paper examines the energy-GDP relationship in the U.S.A. One common method used in analyzing the energy-GDP relationship is energy intensity (also called the intensity of energy use (IEU)), which is the amount of energy required to produce a unit of income (GDP). The paper begins with a substantial literature review of energy intensity studies from around the world. A summary of the findings is discussed, including the factors that were found to directly influence the intensity of energy use. The Kuznets environmental curve is then presented and used in developing a model for the IEU. The model is then tested with data for the U.S.A. from 1949 – to 2003. The results show that energy consumption is very sensitive to energy prices, which in turn impacts the GDP, and that the IEU has declined in the U.S.A. for the period tested, fitting the downward slopping segment of the Kuznets curve.  These results imply that energy conservation policies are desirable

Empirical Study Of The Relationship Between Energy Consumption And Gross Domestic Product In The U.S.A.

The role of energy in the economy is an important issue. There is a general belief and agreement amongst economists, researchers, analysts, and policymakers, that energy consumption is related to economic activity and plays a key role in the process of economic development. However, the precise nature of this relationship between energy consumption and economic growth remains debatable. While some ambiguity has remained regarding the direction of causation--- whether from energy to economy or from economy to energy --- the importance of the energy –GDP interaction is well recognized. Energy use is a necessary input to economic growth and is also a function of growth.  This paper begins with a literature review of the work that has been done to date on the energy-GDP relationship in several countries. Then, an analysis of the historical data for the U.S.A. from 1949 – 2003 is presented along with mathematical models.  The contributions from this paper are that first, we clarify that energy conservation policies will not harm the U.S. economy. Second, we employed a macroeconomic model based on Multiple Model Estimation to determine the relationship between energy consumption and GDP in the United States for the stated time period.  Our model suggests that the causation goes both ways: from energy to the components of GDP, and from GDP to energy consumption

The Impact of Corporate Governance on Voluntary Information Disclosures of Quoted Firms in Nigeria: An Empirical Analysis

Through annual reports, the company provides a lot of voluntary information which is very vital to stakeholders and in corporate governance. The main objective of this study is to empirically investigate the impact of corporate governance on voluntary information disclosures of quoted companies in Nigeria using data from 385 annual reports from a sample of 35 quoted companies during 1999 – 2009. The study also adopted Pre and Post approach to study the significant difference on information disclosures during pre and post corporate governance codes era in Nigeria. A content analysis of the annual reports of sampled companies was carried out with the use of a disclosure checklist developed by the researcher. Multiple regression is employed to test the hypothesis of the study. The study reveals that corporate governance has significant impact on financial reporting of quoted firms in Nigeria and that the level of voluntary disclosure has significantly improved after the introduction of corporate governance codes in Nigeria. Keywords: Corporate governance, voluntary information disclosures, Disclosure index, financial reporting.