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"Wray, Timothy"
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Application of a New One-Equation Turbulence Model to Computation of Separated Flows
Accurate turbulence modeling remains a critical problem in the prediction capability of computational fluid dynamics. One particular area lacking accurate simulations is separated turbulent flows. In this paper, the recently developed one - equation Rahman-Agarwal-Siikonen (RAS) turbulence model is used to simulate the flow of several canonical turbulent flow cases. The commercially available software ANSYS Fluent and the open source software OpenFOAM are used for the flow field calculations. It is shown that the RAS model improves the accuracy of flow simulations compared to the commonly used one - equation Spalart-Allmaras (SA) and two-equation SST k-ω turbulence models.
Journal Article
Development of a One-Equation Eddy Viscosity Turbulence Model for Application to Complex Turbulent Flows
Computational fluid dynamics (CFD) is routinely used in performance prediction and design of aircraft, turbomachinery, automobiles, and in many other industrial applications. Despite its wide range of use, deficiencies in its prediction accuracy still exist. One critical weakness is the accurate simulation of complex turbulent flows using the Reynolds-Averaged Navier-Stokes equations in conjunction with a turbulence model. The goal of this research has been to develop an eddy viscosity type turbulence model to increase the accuracy of flow simulations for mildly separated flows, flows with rotation and curvature effects, and flows with surface roughness. It is accomplished by developing a new zonal one-equation turbulence model which relies heavily on the flow physics; it is now known in the literature as the Wray-Agarwal one-equation turbulence model. The effectiveness of the new model is demonstrated by comparing its results with those obtained by the industry standard one-equation Spalart-Allmaras model and two-equation Shear-Stress-Transport k – ω model and experimental data. Results for subsonic, transonic, and supersonic flows in and about complex geometries are presented. It is demonstrated that the Wray-Agarwal model can provide the industry and CFD researchers an accurate, efficient, and reliable turbulence model for the computation of a large class of complex turbulent flows.
Dissertation
Training Disciplined Soldiers for Christ: The Influence of American Fundamentalism on Prairie Bible Institute During the L.E. Maxwell Era (1922-1980)
This study presents an insider’s view concerning the significant influence of American fundamentalism at Prairie Bible Institute (Three Hills, Alberta, Canada) during the tenure of the school’s co-founder and primary leader, Leslie Earl Maxwell. During much of the period covering 1922-1980, PBI rivaled well-known American schools such as Moody Bible Institute, the Bible Institute of Los Angeles (BIOLA) and Columbia Bible College in Columbia, South Carolina, in size. These schools were also highly efficient in producing hundreds of missionaries and Christian workers to serve the fundamentalist cause in North America and around the world.As a belated response to Dr. John Stackhouse, Jr.’s portrayal of PBI in his 1993 book, Canadian Evangelicalism in the Twentieth Century: An Introduction to Its Character,this thesis offers clarification and modification to Stackhouse’s work regarding how PBI during the Maxwell era should be viewed by students of church history. It is argued here that the ubiquitous influence of the United States of America on Canadian life is clearly visible in the nature of the Christian fundamentalism that prevailed at PBI under Maxwell’s leadership. The work thereby lends a certain amount of credibility to the suggestions made by some scholars that PBI during Maxwell’s career might legitimately be considered an outpost of American fundamentalism.Employing primarily a quantitative assessment of the evidence in combination with personal anecdotes and a few basic statistics, the thesis reveals that Maxwell’s personality and rhetoric were consistently more militant than Stackhouse allows. PBI’s affinity for many of the distinctives of American fundamentalist theology and culture are also documented.Such an approach serves the additional purpose of enabling the writer to call into question the utility of considering militancy the defining characteristic of twentieth-century evangelicalism when considered from a post-9/11 perspective. It also enables a challenge of Stackhouse’s assumption that what he identifies as “sectish” Canadian evangelicalism is ultimately as substantially different from American fundamentalism as the Canadian scholar infers.
Dissertation
Medals are rewards
BURKE, Va.--If there were a medal for informed journalism, David Evans' Nov. 1 column \"Curing the military's modal mania\" would not qualify. The Tribune's Nov. 5 editorial on the subject is also off the mark.
Newspaper Article
Medals are rewards
BURKE, Va.--If there were a medal for informed journalism, David Evans' Nov. 1 column \"Curing the military's medal mania\" would not qualify. The Tribune's Nov. 5 editorial on the subject is also off the mark.
Newspaper Article
Medals are rewards
BURKE, Va.--If there were a medal for informed journalism, David Evans' Nov. 1 column \"Curing the military's modal mania\" would not qualify. The Tribune's Nov. 5 editorial on the subject is also off the mark.
Newspaper Article
Genomic and phenotypic insights from an atlas of genetic effects on DNA methylation
Characterizing genetic influences on DNA methylation (DNAm) provides an opportunity to understand mechanisms underpinning gene regulation and disease. In the present study, we describe results of DNAm quantitative trait locus (mQTL) analyses on 32,851 participants, identifying genetic variants associated with DNAm at 420,509 DNAm sites in blood. We present a database of >270,000 independent mQTLs, of which 8.5% comprise long-range (trans) associations. Identified mQTL associations explain 15-17% of the additive genetic variance of DNAm. We show that the genetic architecture of DNAm levels is highly polygenic. Using shared genetic control between distal DNAm sites, we constructed networks, identifying 405 discrete genomic communities enriched for genomic annotations and complex traits. Shared genetic variants are associated with both DNAm levels and complex diseases, but only in a minority of cases do these associations reflect causal relationships from DNAm to trait or vice versa, indicating a more complex genotype-phenotype map than previously anticipated.
Journal Article
Evaluation of chromatin accessibility in prefrontal cortex of individuals with schizophrenia
Schizophrenia genome-wide association studies have identified >150 regions of the genome associated with disease risk, yet there is little evidence that coding mutations contribute to this disorder. To explore the mechanism of non-coding regulatory elements in schizophrenia, we performed ATAC-seq on adult prefrontal cortex brain samples from 135 individuals with schizophrenia and 137 controls, and identified 118,152 ATAC-seq peaks. These accessible chromatin regions in the brain are highly enriched for schizophrenia SNP heritability. Accessible chromatin regions that overlap evolutionarily conserved regions exhibit an even higher heritability enrichment, indicating that sequence conservation can further refine functional risk variants. We identify few differences in chromatin accessibility between cases and controls, in contrast to thousands of age-related differential accessible chromatin regions. Altogether, we characterize chromatin accessibility in the human prefrontal cortex, the effect of schizophrenia and age on chromatin accessibility, and provide evidence that our dataset will allow for fine mapping of risk variants.
Chromatin accessibility may be altered in disease states. Here the authors carry out ATAC-seq on a large number of samples of dorsolateral prefrontal cortex from individuals with schizophrenia, and healthy controls.
Journal Article