CFD Investigation of Effect of Depth to Diameter Ratio on Dimple Flow // Computational fluid dynamics investigation of effect of depth to diameter ratio on dimple flow dynamics

This study aimed to further the understanding of laminar flow through a dimple with the goal of mitigating flow separation. Dimples of various depth to diameter ratios (0.05, 0.15) were examined for three different dimple diameters and chordwise locations, corresponding to diameter based (ReD) and chordwise location based (Rex) Reynolds number combinations of ReD 20500\Rex 5000, ReD 20500 Rex 77000, and ReD 9000 Rex 21000. For the last combination, a dimple of depth to diameter ratio of 0.25 was also examined. The dimples were placed in a flat plate located in a diverging channel causing an adverse pressure gradient encouraging flow separation near the dimple location. The flow was modeled in the commercial CFD solver Fluent. Results indicate that dimple depth to diameter ratio has a significant effect on the structure of dimple flow. The shallowest dimples showed little change to the overall flow in the channel. Deeper dimples contained dynamic vortical flow structures with behavior varying between each dimple studied. This dynamic vortex activity was observed to be linked with variances in downstream flow. The 0.15 depth to diameter ratio dimples showed behavior very similar to 0.10 ratio dimples investigated elsewhere. The 0.25 dimple show flow different in nature than 0.15 dimples for the same ReD and Rex; the differences were not as stark as those between 0.05 and 0.15 dimples. In light of this and other studies, dimple flow behavior is found to depend on a combination of parameters that eludes direct quantitative parameterization. However, the conclusion is drawn that the most effective dimple will be just deep enough to develop dynamic vortical activity and vortex shedding

Half-quantum vortices on c-axis domain walls in chiral p-wave superconductors

Chiral superconductors are two-fold degenerate and domains of opposite chirality can form, separated by domain walls. There are indications of such domain formation in the quasi two-dimensional putative chiral $p$-wave superconductor Sr$_2$RuO$_4$, yet no experiment has explicitly resolved individual domains in this material. In this work, $c$-axis domain walls lying parallel to the layers in chiral $p$-wave superconductors are explored from a theoretical point of view. First, using both a phenomenological Ginzburg-Landau and a quasiclassical Bogoliubov-deGennes approach, a consistent qualitative description of the domain wall structure is obtained. While these domains are decoupled in the isotropic limit, there is a finite coupling in anisotropic systems and the domain wall can be treated as an effective Josephson junction. In the second part, the formation and structure of half-quantum vortices (HQV) on such $c$-axis domain walls are discussed.Comment: 14 pages, 12 figures; to be submitted to NJ

Concordance between chest X ray (CXR) and point of care ultrasound (POCUS) findings in children diagnosed with RSV infection by nasopharyngeal RT-PCR: the Zambia experience

NIHhttp://www.cs.bu.edu/faculty/betke/papers/Camelo-et-alRSV-POCUS-vs-CXR-Poster.pdfAccepted manuscrip

1-Benzoyl-3-[4-(3-benzoyl­thio­ureido)phen­yl]thio­urea

The mol­ecule of the title compound, C22H18N4O2S2, lies across a crystallographic inversion centre. The mol­ecule adopts a syn–anti configuration with respect to the positions of the carbonyl groups and terminal phenyl rings relative to the thione S atom across the C—N bond. There are two intra­molecular N—H⋯O and C—H⋯S hydrogen bonds within each molecule, resulting in the formation of four six-membered S(6) rings. The central and terminal rings make a dihedral angle of 13.55 (15)°. In the crystal, mol­ecules are linked by inter­molecular C—H⋯S hydrogen bonds, forming R 2 2(14) rings and resulting in zigzag chains

Effects of Wild Pig Disturbance on Forest Vegetation and Soils

In North America, wild pigs (Sus scrofa; feral pigs, feral swine, wild boars) are a widespread exotic species capable of creating large‐scale biotic and abiotic landscape perturbations. Quantification of wild pig environmental effects has been particularly problematic in northern climates, where they occur only recently as localized populations at low densities. Between 2016 and 2017, we assessed short‐term (within ~2 yrs of disturbance) effects of a low‐density wild pig population on forest features in the central Lower Peninsula of Michigan, USA. We identified 16 8‐ha sites using global positioning system locations from 7 radio‐collared wild pigs for sampling.Within each site, we conducted fine‐scale assessments at 81 plots and quantified potential disturbance by wild pigs. We defined disturbance as exposure of overturned soil, often resulting from rooting behavior by wild pigs.We quantified ground cover of plants within paired 1‐m2 frames at each plot, determined effects to tree regeneration using point‐centered quarter sampling, and collected soil cores from each plot. We observed less percent ground cover of native herbaceous plants and lower species diversity, particularly for plants with a coefficient of conservatism ≥5, in plots disturbed by wild pigs.We did not observe an increase in colonization of exotic plants following disturbance, though the observed prevalence of exotic plants was low. Wild pigs did not select for tree species when rooting, and we did not detect any differences in regeneration of light‐ and heavy‐seeded tree species between disturbed or undisturbed plots. Magnesium and ammonium content in soils were lower in disturbed plots, suggesting soil disturbance accelerated leaching of macronutrients, potentially altering nitrogen transformation. Our study suggested that disturbances by wild pigs, even at low densities, alters short‐term native herbaceous plant diversity and soil chemistry. Thus, small‐scale exclusion of wild pigs from vulnerable and rare plant communities may be warranted