Separated laminar boundary layers

Classical boundary layer theory is inadequate to deal with the problem of flow separation owing to its underlying assumption that the boundary layer has an insignificant effect on the external stream. This difficulty is resolved by a theory which includes interaction with the external flow. This theory is described from the viewpoint of the asymptotic triple deck structure. Several triple deck studies are reviewed with emphasis on results of interest in aeronautical applications

Analysis of large bending deformations of a filamentary tubular shell typical for pressure constraint components of space suits

Analysis of large bending deformations of filamentary tubular shell typical for pressure constraint components of space suit

Interacting boundary-layer solutions for laminar separated flow past airfoils

Numerical solutions of the interacting laminar boundary layer equations are presented for two symmetric airfoils at zero incidence: the NACA 0012 and the NACA 66 sub 3-108 airfoils. The potential flow was computed using Carlson's code, and viscous interaction was treated following a Hilbert integral scheme due to Veldman. Effects of various grid parameters are studied, and pressure and skin friction distributions are compared at several Reynolds numbers. For the NACA 0012 airfoil, Reynolds number is varied from a value just below separation (R sub N = 3000) to a value for which extensive separation occurs (R sub N = 100,000). For the 66 sub 3-018 airfoil, results are given at intermediate values (R sub N - 10,000 and 40,000). The method fails to converge for greater values of Reynolds number, corresponding to the development of very thin well separated shear layers where transition to turbulence would occur naturally

Axisymmetric filamentary structures

Axisymmetric filamentary structure

Single-shot Positron Annihilation Lifetime Spectroscopy Using a Liquid Scintillator

Liquid scintillators provide a fast, single component response. However, they traditionally have a low flashpoint and high vapor pressure. We demonstrate the use of an EJ-309 scintillator (high flashpoint and low vapor pressure variant) to acquire single-shot positron annihilation lifetime spectroscopy spectra using a trap-based positron beam

Applied Research Initiative: Training in the Scholarship of Engagement

Extension scholarship and research have become key issues in the United States. We describe a process that was developed in Northwest Ohio to teach applied research skills to field educators using classes, projects, and mentors. This is followed by an analysis of formative and summative evaluations of participants, including an 18-month follow-up survey. The evaluations indicated a general greater understanding and usage of applied research methods and increased involvement in academic papers or presentations. As a result of the evaluations, the program has been revised and is being offered statewide

Predictive coupled-cluster isomer orderings for some Sin{}_nCm{}_m (m,n≤12m, n\le 12) clusters; A pragmatic comparison between DFT and complete basis limit coupled-cluster benchmarks

The accurate determination of the preferred ${\rm Si}_{12}{\rm C}_{12}$ isomer is important to guide experimental efforts directed towards synthesizing SiC nano-wires and related polymer structures which are anticipated to be highly efficient exciton materials for opto-electronic devices. In order to definitively identify preferred isomeric structures for silicon carbon nano-clusters, highly accurate geometries, energies and harmonic zero point energies have been computed using coupled-cluster theory with systematic extrapolation to the complete basis limit for set of silicon carbon clusters ranging in size from SiC$_3$ to ${\rm Si}_{12}{\rm C}_{12}$. It is found that post-MBPT(2) correlation energy plays a significant role in obtaining converged relative isomer energies, suggesting that predictions using low rung density functional methods will not have adequate accuracy. Utilizing the best composite coupled-cluster energy that is still computationally feasible, entailing a 3-4 SCF and CCSD extrapolation with triple-$\zeta$ (T) correlation, the {\it closo} ${\rm Si}_{12}{\rm C}_{12}$ isomer is identified to be the preferred isomer in support of previous calculations [J. Chem. Phys. 2015, 142, 034303]. Additionally we have investigated more pragmatic approaches to obtaining accurate silicon carbide isomer energies, including the use of frozen natural orbital coupled-cluster theory and several rungs of standard and double-hybrid density functional theory. Frozen natural orbitals as a way to compute post MBPT(2) correlation energy is found to be an excellent balance between efficiency and accuracy