Numerical Simulation of Maneuvering Aircraft by Aerodynamic, Flight Mechanics and Structural Mechanics Coupling
Selected results of the DLR Project SikMa-"Simulation of Complex Maneuvers" are presented. The objective of the SikMa Project is to develop and validate a numerical tool to simulate the unsteady aerodynamics of a free flying aeroelastic combat aircraft, by use of coupled aerodynamic, flight mechanics and aeroelastic computations. To achieve this objective, the unstructured, time-accurate flow-solver TAU is coupled with a computational module solving the flight mechanics equations of motion and a structural mechanics code determining the structural deformations. The numerical results are validated by experimental data. For this purpose several specific wind tunnel experiments with different wind tunnel models are carried out.
Open Problems in Computational Steering of Massive Parallel Unstructured Grid Based CFD Simulations
Traditionally, analysis of flow fields resulting from computational fluid dynamics (CFD) calculations is a sequential process. The flow area defined by surrounding geometry is tessellated, a mesh is generated and divided into subregions, transferred to a cluster or supercomputer and the result is transferred back. Then, a variety of post-processing tasks should give insights to the physical problem. At that point, parameters chosen wrong can be identified and the simulation has to be done again with tweaked parameters. This is an iterative process that can be time consuming, especially if one iteration lasts more than a few days. In general, aiming at reducing the simulation times by shortening the time used to identify wrong parameters results in high productivity enhancements. In this paper, the need for on-line monitoring and computational steering approaches for massive parallel unstructured flow simulators are presented with aircraft design as one of many possible application domains. This involves software integration aspects, data streaming and explorative visualization. Many challenges still have to be solved and this paper summarizes most important ones.
Thorium-induced Anatomical and Histopathological Changes in Liver of Swiss Mice
ObjectivePresent study is aimed to investigate the anatomical and histopathological changes in liver tissues of Swiss albino male mice, one month after intravenous administration of thorium (232Th; 4 and 40 mg/kg).MethodsSynchrotron X-ray micro-CT imaging, CD31 immuno-cytochemistry, hematoxylin & eosin staining and Periodic acid-Schiff staining were performed to study changes in liver anatomy, blood vessels/capillaries, histology and glycogen content of liver, respectively.ResultsSynchrotron X-ray micro-CT imaging of liver showed loss of blood vessels in mice treated with thorium (4 mg/kg), which was more prominent at higher dose of thorium (40 mg/kg). These thorium-induced changes in liver were correlated with the decrease in CD31 positive cells and loss of tissue architecture. A dose-dependent increase in glycogen content was also observed in the liver of thorium-treated mice.ConclusionOur results provide novel insight about the effects of thorium on liver, which may have significant implications in understanding the mechanism of thorium thorium-induced hepatotoxicity.