Numerical ABL Wind Tunnel Simulations with Direct Modeling of Roughness Elements through Immersed Boundary Condition Method

Reproduction of atmospheric boundary layer wind tunnel experiments by numerical simulation is achieved in this work by directly modeling with immersed boundary method the geometrical elements placed in the wind tunnel's floor to induce the desired characteristics to the boundary layer.The wind tunnel has a cross section of 2.2 m x 2.25 m, with an inlet region 14 m long and a working region 2 m long. Boundary layer development is shaped up with a series of cubical elements, 3 cm in side, placed in a regular staggered arrangement with a 15 cm spacement. Vortex induction, Standen spires type elements, of 13,4 cm height, and a wall of 31.5 cm height are placed at the inlet. This arrangement is used to reproduce a representative urban site boundary layer (figure 1).The numerical model is implemented on the basis of the open source modelcaffa3d.MBRi [Usera et al 2008], which uses a finite volume method over block structured grids, coupled with various LES approaches for turbulence modeling and parallelization through domain decomposition with MPI [Mendina et al 2013]. Simulations were setup with approximately 2 million cells per block, with a 26 block arrangement. The computational grid is horizontally uniform with a resolution of 1.04 cm x 1.04 cm and nonuniform in vertical direction with the grid points concentrated near the floor . The grid spacing is geometrically stretched away from the floor with a minimum value of 1mm. The time step is 0.1 second and the computation is distributed in 26 cores on the Cluster-FING infraestructure [www.fing.edu.uy/cluster]. The Immersed boundary method approach followed the work of [Liao et al 2009]. Numerical simulation results are compared to wind tunnel measurements for the mean velocity profiles (figure 2), rms profiles and spectrums, providing good overall agreement. We conclude that the Immersed Boundary Condition method is a promising approach to numerically reproduce ABL Boundary Layer development methods used in physical modeling.Agencia Nacional de Investigación e Innovació

Finite volume simulation of 2-D steady square lid driven cavity flow at high reynolds numbers

In this work, computer simulation results of steady incompressible flow in a 2-D square lid-driven cavity up to Reynolds number (Re) 65000 are presented and compared with those of earlier studies. The governing flow equations are solved by using the finite volume approach. Quadratic upstream interpolation for convective kinematics (QUICK) is used for the approximation of the convective terms in the flow equations. In the implementation of QUICK, the deferred correction technique is adopted. A non-uniform staggered grid arrangement of 768x768 is employed to discretize the flow geometry. Algebraic forms of the coupled flow equations are then solved through the iterative SIMPLE (Semi-Implicit Method for Pressure-Linked Equation) algorithm. The outlined computational methodology allows one to meet the main objective of this work, which is to address the computational convergence and wiggled flow problems encountered at high Reynolds and Peclet (Pe) numbers. Furthermore, after Re > 25000 additional vortexes appear at the bottom left and right corners that have not been observed in earlier studies

Reduced Cancer Incidence in Huntington's Disease: Analysis in the Registry Study

Background: People with Huntington’s disease (HD) have been observed to have lower rates of cancers. Objective: To investigate the relationship between age of onset of HD, CAG repeat length, and cancer diagnosis. Methods: Data were obtained from the European Huntington’s disease network REGISTRY study for 6540 subjects. Population cancer incidence was ascertained from the GLOBOCAN database to obtain standardised incidence ratios of cancers in the REGISTRY subjects. Results: 173/6528 HD REGISTRY subjects had had a cancer diagnosis. The age-standardised incidence rate of all cancers in the REGISTRY HD population was 0.26 (CI 0.22–0.30). Individual cancers showed a lower age-standardised incidence rate compared with the control population with prostate and colorectal cancers showing the lowest rates. There was no effect of CAG length on the likelihood of cancer, but a cancer diagnosis within the last year was associated with a greatly increased rate of HD onset (Hazard Ratio 18.94, p < 0.001). Conclusions: Cancer is less common than expected in the HD population, confirming previous reports. However, this does not appear to be related to CAG length in HTT. A recent diagnosis of cancer increases the risk of HD onset at any age, likely due to increased investigation following a cancer diagnosis

The V471A polymorphism in autophagy-related gene ATG7 modifies age at onset specifically in Italian Huntington disease patients

The cause of Huntington disease (HD) is a polyglutamine repeat expansion of more than 36 units in the huntingtin protein, which is inversely correlated with the age at onset of the disease. However, additional genetic factors are believed to modify the course and the age at onset of HD. Recently, we identified the V471A polymorphism in the autophagy-related gene ATG7, a key component of the autophagy pathway that plays an important role in HD pathogenesis, to be associated with the age at onset in a large group of European Huntington disease patients. To confirm this association in a second independent patient cohort, we analysed the ATG7 V471A polymorphism in additional 1,464 European HD patients of the “REGISTRY” cohort from the European Huntington Disease Network (EHDN). In the entire REGISTRY cohort we could not confirm a modifying effect of the ATG7 V471A polymorphism. However, analysing a modifying effect of ATG7 in these REGISTRY patients and in patients of our previous HD cohort according to their ethnic origin, we identified a significant effect of the ATG7 V471A polymorphism on the HD age at onset only in the Italian population (327 patients). In these Italian patients, the polymorphism is associated with a 6-years earlier disease onset and thus seems to have an aggravating effect. We could specify the role of ATG7 as a genetic modifier for HD particularly in the Italian population. This result affirms the modifying influence of the autophagic pathway on the course of HD, but also suggests population-specific modifying mechanisms in HD pathogenesis

Ein Finite-Volumen-Verfahren zur Berechnung von inkompressiblen und kompressiblen Stroemungen in komplexen Geometrien mit beweglichen Raendern und freien Oberflaechen

In this work an implicit finite-volume method for solving problems of fluid mechanics is presented. The method uses Cartesian velocity components and block structured non-orthogonal boundary fitted grids. The well known SIMPLE-algorithm is employed as basis for the pressure velocity coupling. The transport equations in integral coordinate-free form are discretized with up to fourth order accuracy. The method is extended to predict flows at all speeds. To account for turbulent flows, two equation turbulent models k-#epsilon# and k-#epsilon#-RNG are implemented. The method can predict two- and three-dimensional viscous flows with free surfaces. A wide range of fluid flow problems have been solved to demonstrate capabilities and efficiency of the presented method. (orig.)Available from TIB Hannover: RA 489(563) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Ein Berechnungsverfahren fuer dreidimensionale, viskose Stroemungen mit freien Oberflaechen

A video tape on sloshing processes in large tanks completes this report. The tape can be obtained from the lending library at Institut fuer SchiffbauAvailable from TIB Hannover: RA 489(553) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Outcome of the workshop : C.S.I. Pollen – training the national agents in Graz

On 6th and 7th of February 2014, 26 researchers attended a workshop in Graz, Austria. The workshop was supported by COLOSS, the University of Graz and the Dean of the Faculty of Science. Pollen is the only source of proteins for honey bee colonies and is needed to feed brood, for organ development of adult honey bees and build-up of reserves to become long lived winter bees. All participants welcomed the initiative and agreed that the pollen nutrition of honey bees is of great importance for colony health and survival, and needs to be adequately studied. A means to study the biodiversity of pollen in the supply of honey bee colonies on a large scale is through the involvement of beekeepers as Citizen Scientists (C.S.). As beekeepers cannot perform full palynological analyses, we have developed a simple estimation of pollen diversity according to the colour of corbicular pollen pellets. This allows us to obtain information on a large number of samples, but also requires standardized protocols in all participating countries. National coordinators from the following countries agreed to conduct a common investigation in 2014 and 2015 using the protocols developed for C.S.I. Pollen in pilot studies in 2013: National coordinators of the following countries were present: Austria, Croatia , Denmark, England, France, Ireland, Italy, Netherlands, Norway, Romania, Scotland, Slovenia, Spain, Sweden, Switzerland and Wales. We will re-evaluate the protocols after one year, and also invite other countries to join. As a second step, samples collected by the beekeeper can be analysed to connect pollen diversity derived from colour differentiation of pollen pellets, to the number of plant species identified by palynological analysis. The funding for this second level investigation is to be left to the national coordinators. Traditional melissopalynological methods are not as suitable for the analysis of corbicular pollen pellets compared to honey, so standardized methods for this will be developed. The methods of sub-sampling, storage and transport need to be developed. The first level C.S. Investigations in the different countries will be coordinated and data collected for joint analyses and publication