Influence of the coiling porosity on the risk reduction of the cerebral aneurysm rupture: computational study

The formation and progress of cerebral aneurysm is highly associated with hemodynamic factors and blood flow feature. In this study, comprehensive efforts are done to investigate the blood hemodynamic effects on the creation and growth of the Internal Carotid Artery. The computational fluid dynamic method is used for the visualization of the bloodstream inside the aneurysm. Transitional, non-Newtonian and incompressible conditions are considered for solving the Navier-Stokes equation to achieve the high-risk region on the aneurysm wall. OSI and WSS of the aneurysm wall are compared within different blood flow stages. The effects of blood viscosity and coiling treatment on these factors are presented in this work. Our study shows that in male patients (HCT = 0.45), changing the porosity of coiling from 0.89 with 0.79 would decreases maximum OSI up to 75% (in maximum acceleration). However, this effect is limited to about 45% for female patients (HCT = 0.35)

Effect of cavity back height on mixing efficiency of hydrogen multi-jets at supersonic combustion chamber

© 2020 Hydrogen Energy Publications LLC Stable fuel distribution and mixing is noteworthy for increasing the efficiency of the scramjet engine at high-speed flight. In this work, numerical studies are accomplished to inspect and disclose the effects of cavity back height on the fuel (hydrogen) spreading inside the cavity flameholder at supersonic flow. The effects of both positive and negative back height on fuel distribution are explained by analysis of the three-dimensional jet contour. The implications of multi-jets directions on the hydrogen distribution are also presented in this research. RANS equations with the SST turbulence model are employed for the computational investigations of 3-D supersonic air and fuel inside the cavity. Our outcomes show that the injection of the opposing multi-jets is more effective on fuel mixing when the back height is positive. However, multi hydrogen co-jet distributes the fuel jets homogenous inside the cavity for negative cavity back height. According to our results, the weakening the main circulation improves the mixing performance inside the cavity