Blunt-body configurations are the most common geometries adopted for non-lifting re-entry vehicles. Hypersonic re-entry vehicles experience different flow regimes during flight due to drastic changes in atmospheric density. The conventional Navier-Stokes-Fourier equations with no-slip and no-jump boundary conditions may not provide accurate information regarding the aerothermodynamic properties of blunt-bodies in flow regimes away from the continuum. In addition, direct simulation Monte Carlo method requires significant computational resources to analyze the near-continuum flow regime. To overcome these shortcomings, the Navier-Stokes-Fourier equations with slip and jump conditions were numerically solved. A mixed-type modal discontinuous Galerkin method was employed to achieve the appropriate numerical accuracy. The computational simulations were conducted for different blunt-body configurations with varying freestream Mach and Knudsen numbers. The results show that the drag coefficient decreases with an increased Mach number, while the heat flux coefficient increases. On the other hand, both the drag and heat flux coefficients increase with a larger Knudsen number. Moreover, for an Apollo-like blunt-body configuration, as the flow enters into non-continuum regimes, there are considerable losses in the lift-to-drag ratio and stability.
The increasing energy consumption has become a major concern in cloud computing due to its cost and environmental damage. Virtual Machine placement algorithms have been proven to be very effective in increasing energy efficiency and thus reducing the costs. In this paper we have introduced a new priority routing VM placement algorithm and have compared it with PABFD (power-aware best fit decreasing) on CoMon dataset using CloudSim for simulation. Our experiments show the superiority of our new method with regards to energy consumption and level of SLA violations measures and prove that priority routing VM placement algorithm can be effectively utilized to increase energy efficiency in the clouds.
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