Evaluation of grey area mitigation tools within zonal and non-zonal RANS-LES approaches in flows with pressure induced separation

Hybrid RANS-LES computations of the separated flow over a wall-mounted hump are presented, which employ different grey-area mitigation techniques in the framework of a structured and an unstructured flow solver. Two zonal approaches using different synthetic-turbulence generators at the RANS-LES inter- face, as well as a non-zonal approach based on a shear-layer-adapted subgrid scale are compared in detail with validation data from a wind-tunnel experiment. Irrespective of the applied flow solver, the differ- ent methods are shown to be similarly effective in reducing the grey area compared to the basic hybrid RANS-LES model, and thus provide satisfying mean-flow predictions of the pressure-induced separation

Healthcare-associated infections in pediatric cancer patients: results of a prospective surveillance study from university hospitals in Germany and Switzerland

<p>Abstract</p> <p>Background</p> <p>Pediatric cancer patients face an increased risk of healthcare-associated infection (HAI). To date, no prospective multicenter studies have been published on this topic.</p> <p>Methods</p> <p>Prospective multicenter surveillance for HAI and nosocomial fever of unknown origin (nFUO) with specific case definitions and standardized surveillance methods.</p> <p>Results</p> <p>7 pediatric oncology centers (university facilities) participated from April 01, 2001 to August 31, 2005. During 54,824 days of inpatient surveillance, 727 HAIs and nFUOs were registered in 411 patients. Of these, 263 (36%) were HAIs in 181 patients, for an incidence density (ID) (number of events per 1,000 inpatient days) of 4.8 (95% CI 4.2 to 5.4; range 2.4 to 11.7; P < 0.001), and 464 (64%) were nFUO in 230 patients. Neutropenia at diagnosis correlated significantly with clinical severity of HAI. Of the 263 HAIs, 153 (58%) were bloodstream infections (BSI). Of the 138 laboratory-confirmed BSIs, 123 (89%) were associated with use of a long-term central venous catheter (CVAD), resulting in an overall ID of 2.8 per 1,000 utilization days (95% CI 2.3 to 3.3). The ID was significantly lower in Port-type than in Hickman-type CVADs. The death of 8 children was related to HAI, including six cases of aspergillosis. The attributable mortality was 3.0% without a significant association to neutropenia at time of NI diagnosis.</p> <p>Conclusion</p> <p>Our study confirmed that pediatric cancer patients are at an increased risk for specific HAIs. The prospective surveillance of HAI and comparison with cumulative multicenter results are indispensable for targeted prevention of these adverse events of anticancer treatment.</p

Results and Lessons learned from the EU-Project ATAAC

This paper presents results and lessons learned from the European collaborative project “Advanced Turbulence simulation for Aerodynamic Application Challenges” (ATAAC). Besides selected results from test cases used for assessment of turbulence modelling approaches in the project, some lessons learnt as well as best practice guidelines will be presented

Results and Lessons learned from the EU-Project ATAAC

This paper presents results and lessons learned from the European collaborative project “Advanced Turbulence simulation for Aerodynamic Application Challenges” (ATAAC). Besides selected results from test cases used for assessment of turbulence modelling approaches in the project, some lessons learnt as well as best practice guidelines will be presented

Development of CFD Tools at DLR - Activities Trends

Development of CFD Tool