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For improvement of prediction of acoustics waves from a rocket plume, validation studies of numerical simulation are performed using experimental data of acoustics waves from subscale rocket motors, and prediction accuracy of numerical simulation is discussed. Experimental data of flow and acoustics fields of a solid motor and a H2-AIR liquid motor are used as the reference. The computational results of the far-field OASPL agree with experimental data within the error of approximately 5dB. The result shows that the current numerical methods well predict Mach waves at downstream side even though the results of far-field PSD are slightly overestimated. Meanwhile, it is difficult to capture shock associated acoustic waves and fine-scale turbulence acoustic waves at upstream side and the results of far-field PSD are underestimated. In addition, difference between single and multicomponent in the computational results is also small.

This study was performed to determine the relations between the features of wall shear stress and aneurysm rupture. For this purpose, visual data mining was performed in unsteady blood flow simulation data for an aortic aneurysm. The time-series data of wall shear stress given at each grid point were converted to spatial and temporal indices, and the grid points were sorted using a self-organizing map based on the similarity of these indices. Next, the results of cluster analysis were mapped onto the real space of the aortic aneurysm to specify the regions that may lead to aneurysm rupture. With reference to previous reports regarding aneurysm rupture, the visual data mining suggested specific hemodynamic features that cause aneurysm rupture.Graphical Abstract

The effects of Mach number at Re = 3,000 for different airfoils (NACA0012, NACA0002, NACA4412, NACA4402) with thickness and camber geometries are investigated for the propeller blade design of a Mars airplane. The present study shows that thin and cambered airfoils have larger variations in C l than symmetric airfoils. As for thin airfoils, C l at higher ¡ has rapid increases when the M¨is low. This is because the flow separation occurs at the leading edge, and the flow is reattached on the airfoil surface. However, the rapid increase in C l disappear as M¨increases because the flow reattachment does not occurs. As for cambered airfoils, the decrease in C l becomes larger than that on the symmetric airfoils when M¨is higher. This is because C p near the leading edge on the lower surface is smaller than that on the upper surface and the high-speed region on the lower side of the leading edge is enlarged as M¨increases. Then, the M cr at Re = 3,000 tends to be larger than that predicted by linear theory.