Subgrid modeling for reacting large eddy simulations

Development of accurate combustion models is needed to aid in the design of improved combustors in both the aircraft and automotive industries. Numerical models capable of providing the necessary information must be able to predict the highly unsteady behavior associated with turbulent-chemistry interactions. One promising approach to investigate flows of practical interest is large-eddy simulation (LES). However, relatively few extensions to reacting flows have been made since additional closure problems arise from combustion-related terms which are difficult to model. One approach to combustion related subgrid closure is the linear-eddy mixing (LEM) model. This model separately treats the physical process of molecular diffusion and turbulent stirring so that an accurate picture of the interaction of the turbulence and the chemistry can be obtained. This paper investigates the LEM model for use in LES simulations of diffusion flames

Resolving the neural circuits of anxiety

Although anxiety disorders represent a major societal problem demanding new therapeutic targets, these efforts have languished in the absence of a mechanistic understanding of this subjective emotional state. While it is impossible to know with certainty the subjective experience of a rodent, rodent models hold promise in dissecting well-conserved limbic circuits. The application of modern approaches in neuroscience has already begun to unmask the neural circuit intricacies underlying anxiety by allowing direct examination of hypotheses drawn from existing psychological concepts. This information points toward an updated conceptual model for what neural circuit perturbations could give rise to pathological anxiety and thereby provides a roadmap for future therapeutic development.National Institute of Diabetes and Digestive and Kidney Diseases (U.S.) (NIH Director’s New Innovator Award DP2-DK-102256-01)National Institute of Mental Health (U.S.) (NIH) R01-MH102441-01)JPB Foundatio

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

On subgrid combustion modeling for large-eddy simulations

Ph.D