This work deals with a numerical study on forward-facing steps situated in a supersonic flow. The primary aim of this paper is to examine the sensitivity of the velocity, density, pressure and temperature due to the step-height variations of such forward-facing steps. Effects on the flowfield structure due to variations on the step height have been investigated by employing the Direct Simulation Monte Carlo (DSMC) method. The studied parameter contours for various values of step heights and profiles in three different sections of the channel are obtained. The results indicate that the fluid flow and temperature characteristics considerably depend on the step heights. The results were also compared with the previously published works which approved outstanding validation.

The aim of the present study is deriving an analytical solution to incompressible thermal flow in a Micro-Couette geometry in the presence of a pressure gradient using Burnett equations with first-and second-order slip boundary conditions. The lower plate of the Micro-Couette structure is stationary, whereas the upper plate moves at a constant velocity. Non-dimensional axial velocity and temperature profiles were obtained using the slip boundary conditions and were compared with the transition flow regime (0. 1≤ Kn ≤ 10). The results showed that in this regime, rarefaction exerts a considerable effect on both the velocity and the temperature profiles. Because of the presence of the pressure gradient in the direction of the flow, the non-dimensional velocity and temperature profiles behave in a parabolic trend and flatten as the Knudsen number increases. The Poiseuille and Nusselt numbers, obtained using the derived analytical solution, decrease with increasing the Knudsen number. In the absence of an axial pressure gradient, the velocity profile behaves linearly and shows good agreement with the results of the previous works.

The standard LBM with the relaxation time is only able to simulate the flow features in continuum and slip regimes. In the present paper, a new relaxation time formulation considering the rarefaction effect on the viscosity for the lattice Boltzmann simulation of shear driven flows is presented in order to cover wide range of the flow regimes. The results show that in spite of the standard Lattice Boltzmann Method, LBM, the presented relaxation time equation is able to predict flow features in wide range of flow regimes including slip, transition and to some extend free molecular flow regimes. The velocity profiles, slip length and shear stress agree very well with DSMC (Direct Simulation Monte Carlo) and linear Boltzmann results.

The concerns about the possible risk of manufactured nanoparticles (NPs) have been raised recently. nano-and Micro-sized copper oxide (CO and CONP) are widely used in many industries. In this regard, in-vitro studies have demonstrated that CONP is a toxic compound in different cell lines. Despite their unique properties, NPs possess unexpected toxicity profiling relative to the bulk materials. This study was designed to examine and compare the toxic effects of CO and CONPs in-vivo and in isolated rat mitochondria. Male Wistar albino rats received 50 to 1000 mg/kg CO or CONP by gavage and several toxicological endpoints including biochemical indices and oxidative stress markers. Then, the pathological parameters in the multiple organs such as liver, brain, spleen, kidney, and intestine were assessed. Mitochondria were isolated from the rat liver and several mitochondrial indices were measured. The results of this study demonstrated that CO and CONP exhibited biphasic dose-response effects. CONPs showed higher toxicity compared with the bulk material. There were no significant changes in the results of CONP and CO in isolated rat liver mitochondria. The present studies provided more information regarding the hormetic effects of CO and CONPs in-vivo and in isolated rat mitochondria.