Application of the FUN3D Unstructured-Grid Navier-Stokes Solver to the 4th AIAA Drag Prediction Workshop Cases

FUN3D Navier-Stokes solutions were computed for the 4th AIAA Drag Prediction Workshop grid convergence study, downwash study, and Reynolds number study on a set of node-based mixed-element grids. All of the baseline tetrahedral grids were generated with the VGRID (developmental) advancing-layer and advancing-front grid generation software package following the gridding guidelines developed for the workshop. With maximum grid sizes exceeding 100 million nodes, the grid convergence study was particularly challenging for the node-based unstructured grid generators and flow solvers. At the time of the workshop, the super-fine grid with 105 million nodes and 600 million elements was the largest grid known to have been generated using VGRID. FUN3D Version 11.0 has a completely new pre- and post-processing paradigm that has been incorporated directly into the solver and functions entirely in a parallel, distributed memory environment. This feature allowed for practical pre-processing and solution times on the largest unstructured-grid size requested for the workshop. For the constant-lift grid convergence case, the convergence of total drag is approximately second-order on the finest three grids. The variation in total drag between the finest two grids is only 2 counts. At the finest grid levels, only small variations in wing and tail pressure distributions are seen with grid refinement. Similarly, a small wing side-of-body separation also shows little variation at the finest grid levels. Overall, the FUN3D results compare well with the structured-grid code CFL3D. The FUN3D downwash study and Reynolds number study results compare well with the range of results shown in the workshop presentations

Towards Full Aircraft Airframe Noise Prediction: Detached Eddy Simulations

Results from a computational study on the aeroacoustic characteristics of an 18%-scale, semi-span Gulf-stream aircraft model are presented in this paper. NASA's FUN3D unstructured compressible Navier-Stokes solver was used to perform steady and unsteady simulations of the flow field associated with this high-fidelity aircraft model. Solutions were obtained for free-air at a Mach number of 0.2 with the flap deflected at 39 deg, with the main gear off and on (the two baseline configurations). Initially, the study focused on accurately predicting the prominent noise sources at both flap tips for the baseline configuration with deployed flap only. Building upon the experience gained from this initial effort, subsequent work involved the full landing configuration with both flap and main landing gear deployed. For the unsteady computations, we capitalized on the Detached Eddy Simulation capability of FUN3D to capture the complex time-dependent flow features associated with the flap and main gear. To resolve the noise sources over a broad frequency range, the tailored grid was very dense near the flap inboard and outboard tips and the region surrounding the gear. Extensive comparison of the computed steady and unsteady surface pressures with wind tunnel measurements showed good agreement for the global aerodynamic characteristics and the local flow field at the flap inboard tip. However, the computed pressure coefficients indicated that a zone of separated flow that forms in the vicinity of the outboard tip is larger in extent along the flap span and chord than measurements suggest. Computed farfield acoustic characteristics from a FW-H integral approach that used the simulated pressures on the model solid surface were in excellent agreement with corresponding measurements

In vitro activities of tetracyclines against different clones of multidrug-resistant Acinetobacter baumannii isolates from two Iranian hospitals.

Acinetobacter baumannii has emerged as one of the most challenging healthcare-related pathogens and its occurrence has increased worldwide, especially in patients admitted to intensive care units. A. baumannii isolates are frequently resistant to multiple antimicrobial agents and there are recent reports of isolates resistant to virtually all clinically relevant drugs. In the present study, the in vitro activities of tigecycline, minocycline and doxycycline against 67 MDR-AB isolates recovered from 29 burn and 38 non-burn Iranian patients hospitalised in Tehran and Tabriz, respectively, were studied. Tigecycline and minocycline may be still considered effective therapeutic options for MDR-AB infections. However, ongoing monitoring of A. baumannii susceptibility to these antibiotics is required

Implementation of Flow Tripping Capability in the USM3D Unstructured Flow Solver

A flow tripping capability is added to an established NASA tetrahedral unstructured parallel Navier-Stokes flow solver, USM3D. The capability is based on prescribing an appropriate profile of turbulence model variables to energize the boundary layer in a plane normal to a specified trip region on the body surface. We demonstrate this approach using the k-e two-equation turbulence model of USM3D. Modification to the solution procedure primarily consists of developing a data structure to identify all unstructured tetrahedral grid cells located in the plane normal to a specified surface trip region and computing a function based on the mean flow solution to specify the modified profile of the turbulence model variables. We leverage this data structure and also show an adjunct approach that is based on enforcing a laminar flow condition on the otherwise fully turbulent flow solution in user specified region. The latter approach is applied for the solutions obtained using other one- and two-equation turbulence models of USM3D. A key ingredient of the present capability is the use of a graphical user-interface tool PREDISC to define a trip region on the body surface in an existing grid. Verification of the present modifications is demonstrated on three cases, namely, a flat plate, the RAE2822 airfoil, and the DLR F6 wing-fuselage configuration

Deformation of Unstructured Viscous Grids

A mesh deformation algorithm for unstructured grids is presented. It is designed for high Reynolds number flow problems. Such grids are employed in aerodynamic and aeroelastic studies of wings or complete aircraft configurations in flows where the viscous effects are important. Given a surface deformation, the method efficiently recalculates new locations of high aspect ratio cells that make up the viscous layers of the grid and then deforms the inviscid part of the grid using an established method based on a torsional spring analogy technique. Results are presented for monitoring the deterioration of the quality of the grid during subsequent deformation steps for aeroelastic studies as well as to ensure the time efficiency of the method. Results for grid deformation of a 1.4 million cell AGARD 445.6 wing grid designed for flow at high Reynolds numbers due to typical deformations are also presented. Finally, a discussion of the parallelization performance and comparison of the running time of the mesh deformation algorithm to that used by the flow solver is made

Determination of Ochratoxin A in the rainbow trout (Oncorhynchus mykiss) feed in Chaharmahal Va Bakhtiary province by ELISA assay

Ochratoxins are considered as the significant mycotoxins found in animal feeds. Amongst, Ochratoxin A has high pathological consequences on the humans and animals. The aim of present study was to determine the amount of Ochratoxin A in rainbow trout feed produced in Chaharmahal Va Bakhtiary province. For this, four major producers of trout feed were chosen and four different sizes of feed together with one wheat flour sample were obtained from each factory. The samples were transferred to Food Analysis Lab of Shahre-Kord Islamic Azad University. The samples were obtained in three replicates and a total of 60 samples were analyzed for the presence of Ochratoxin A. The analysis was performed by ELISA assay. Results revealed that the quantity of Ochratoxin A in all feed samples were lower than determined contamination level established by Iranian National Standard and EU commission (5µg/kg). However, the contamination levels in all wheat flour samples were higher than defined standard. The amount of Ochratoxin A in samples obtained from various producers was not statistically significant (

Desinfektionsleistung von Mikrowellen gegenüber Bacillus subtilis als Indikatororganismus auf kontaminierten Dentalabgüssen unter trockenen und feuchten Bedingungen

Objective: The disinfection of dental stone casts using microwave radiation has been shown, but doubts remain regarding its efficacy under various conditions. The aim of the present study was to evaluate the efficacy of microwave disinfection on wet and dry dental stone casts contaminated by a resistant microorganism. Material and methods: In this in vitro study, 34 stone half-casts were prepared, contaminated with Bacillus subtilis and divided into two groups. After drying the specimens of one group for 15 minutes using 450 W microwave energy, all the wet and dry specimens were exposed to 900 W microwave energy for 5 minutes. Specimens were then individually transferred to nutrient broth culture medium and after 10 minutes, one milliliter from each tube was cultured in nutrient agar media for 24 hours, and the colonies were counted in CFU/mL. Data were analyzed using multifactorial ANOVA and Bonferroni tests.Results: Casts in both wet and dry groups were disinfected to a high level (6 log), with no statistically significant differences between them (P<0.05). Conclusion: According to the results, microwave irradiation can disinfect dental stone casts to a high degree, irrespective of moisture level. However, the result should be confirmed by exploring with other species of resistant microorganisms.Zielsetzung: Obwohl die Desinfektion von Dentalabgüssen mit Mikrowellen bereits gezeigt werden konnte, bestehen Zweifel hinsichtlich der Wirksamkeit unter verschiedenen Bedingungen. Daher sollte die Wirksamkeit vergleichend auf nassen und trockenen Dentalabgüssen nach Kontamination mit Bacillus subtilis in vitro geprüft werden.Material und Methode: 34 Zahnabgüsse wurden präpariert, mit B. subtilis kontaminiert und in zwei Gruppen aufgeteilt. In der ersten Gruppe wurden die Prüfkörper mit 450 W Mikrowellenenergie für 15 min getrocknet. Danach wurden die getrockneten und parallel die feucht belassenen Prüfkörper für 5 min mit 900 W Mikrowellenenergie exponiert, für 10 min in Nährbouillon überführt, davon 1 ml auf Agar ausplattiert und nach 24 h die Kolonien gezählt. Die Daten wurden nach mehrfaktorieller Varianzanalyse mittels ANOVA mit dem Bonferroni-Test analysiert.Ergebnisse: In beiden Gruppen wurde eine Abtötung um 6-log ohne signifikanten Unterschied erreicht (P<0.05).Schlussfolgerung: Mittels Mikrowellen (900 W) können Dentalabgüssen, unabhängig ob sie trocken oder feucht sind, desinfiziert werden. Allerdings sollte das Ergebnis durch Prüfung mit weiteren Testspezies untermauert werden