Conservative treatment of boundary interfaces for overlaid grids and multi-level grid adaptations

Conservative algorithms for boundary interfaces of overlaid grids are presented. The basic method is zeroth order, and is extended to a higher order method using interpolation and subcell decomposition. The present method, strictly based on a conservative constraint, is tested with overlaid grids for various applications of unsteady and steady supersonic inviscid flows with strong shock waves. The algorithm is also applied to a multi-level grid adaptation in which the next level finer grid is overlaid on the coarse base grid with an arbitrary orientation

High-Order Polynomial Expansions (HOPE) for flux-vector splitting

The Van Leer flux splitting is known to produce excessive numerical dissipation for Navier-Stokes calculations. Researchers attempt to remedy this deficiency by introducing a higher order polynomial expansion (HOPE) for the mass flux. In addition to Van Leer's splitting, a term is introduced so that the mass diffusion error vanishes at M = 0. Several splittings for pressure are proposed and examined. The effectiveness of the HOPE scheme is illustrated for 1-D hypersonic conical viscous flow and 2-D supersonic shock-wave boundary layer interactions

Development of a new flux splitting scheme

The use of a new splitting scheme, the advection upstream splitting method, for model aerodynamic problems where Van Leer and Roe schemes had failed previously is discussed. The present scheme is based on splitting in which the convective and pressure terms are separated and treated differently depending on the underlying physical conditions. The present method is found to be both simple and accurate

High-Order Polynomial Expansions (HOPE) for flux-vector splitting

The Van Leer flux splitting is known to produce excessive numerical dissipation for Navier-Stokes calculations. Researchers attempt to remedy this deficiency by introducing a higher order polynomial expansion (HOPE) for the mass flux. In addition to Van Leer's splitting, a term is introduced so that the mass diffusion error vanishes at M equals 0. Several splittings for pressure are proposed and examined. The effectiveness of the HOPE scheme is illustrated for 1-D hypersonic conical viscous flow and 2-D supersonic shock-wave boundary layer interactions. Also, the authors give the weakness of the scheme and suggest areas for further investigation

A new flux splitting scheme

A new flux splitting scheme is proposed. The scheme is remarkably simple and yet its accuracy rivals and in some cases surpasses that of Roe's solver in the Euler and Navier-Stokes solutions performed in this study. The scheme is robust and converges as fast as the Roe splitting. An approximately defined cell-face advection Mach number is proposed using values from the two straddling cells via associated characteristic speeds. This interface Mach number is then used to determine the upwind extrapolation for the convective quantities. Accordingly, the name of the scheme is coined as Advection Upstream Splitting Method (AUSM). A new pressure splitting is introduced which is shown to behave successfully, yielding much smoother results than other existing pressure splittings. Of particular interest is the supersonic blunt body problem in which the Roe scheme gives anomalous solutions. The AUSM produces correct solutions without difficulty for a wide range of flow conditions as well as grids

Aquarium dermatitis: Cercarial dermatitis in an aquarist

A 33-year-old man presented with very itchy red papules on the back of his hands and forearms. These papules appeared about 90 min after he had cleaned his aquarium in which he kept native fish and watersnails. He had obtained the watersnails some weeks before from a nearby pond. Examination of water from the aquarium revealed cercariae. The clinical diagnosis of cercarial dermatitis was corroborated. Cercarial dermatitis has repeatedly been seen in swimmers but not in aquarists keeping fish in a home aquarium

Gran Telescopio Canarias OSIRIS Transiting Exoplanet Atmospheric Survey: Detection of potassium in XO-2b from narrowband spectrophotometry

We present Gran Telescopio Canarias (GTC) optical transit narrow-band photometry of the hot-Jupiter exoplanet XO-2b using the OSIRIS instrument. This unique instrument has the capabilities to deliver high cadence narrow-band photometric lightcurves, allowing us to probe the atmospheric composition of hot Jupiters from the ground. The observations were taken during three transit events which cover four wavelengths at spectral resolutions near 500, necessary for observing atmospheric features, and have near-photon limited sub-mmag precisions. Precision narrow-band photometry on a large aperture telescope allows for atmospheric transmission spectral features to be observed for exoplanets around much fainter stars than those of the well studied targets HD209458b and HD189733b, providing access to the majority of known transiting planets. For XO-2b, we measure planet-to-star radius contrasts of R_pl/R_star=0.10508+/-0.00052 at 6792 Ang, 0.10640+/-0.00058 at 7582 Ang, and 0.10686+/-0.00060 at 7664.9 Ang, and 0.10362+/-0.00051 at 8839 Ang. These measurements reveal significant spectral features at two wavelengths, with an absorption level of 0.067+/-0.016% at 7664.9 Ang due to atmospheric potassium in the line core (a 4.1-sigma significance level), and an absorption level of 0.058+/-0.016% at 7582 Ang, (a 3.6-sigma significance level). When comparing our measurements to hot-Jupiter atmospheric models, we find good agreement with models which are dominated in the optical by alkali metals. This is the first evidence for potassium in an extrasolar planet, an element that has long been theorized along with sodium to be a dominant source of opacity at optical wavelengths for hot Jupiters.Comment: 11 pages, 6 figures, accepted in A&A, minor changes to wording, primarily section 4.2, and the title has also been slightly modifie