Simulations of micropolar nanofluid-equipped natural convective-driven flow in a cavity

Purpose This paper aims to focus on the natural convective flow analysis of micropolar nanofluid fluid in a rectangular vertical container. A heated source is placed in the lower wall to generate the internal flow. In further assumptions, the left/right wall are kept cool, while the upper and lower remaining portions are insulated. Free convection prevails in the regime because of thermal difference in-between the lower warmer and upper colder region. Design/methodology/approach The physical setup owns mathematical framework in-terms of non-linear partial differential equations. For the solution purpose of the differential system, finite volume method is adopted. The interesting features of the flow along with thermal transportation involve both translational and rotational movement of fluid particles. Findings Performing the simulations towards flow controlling variables the outputs are put together in contour maps and line graphs. It is indicated that the variations in flow profile mass concentration and temperature field augments at higher Rayleigh parameter because of stronger buoyancy effects. Higher viscosity coefficient implies decrease in flow and thermal transportation. Further, the average heat transfer rate also grows by increasing both the Rayleigh parameter and heated source length. Originality/value To the best of the authors’ knowledge, no such study has been addressed yet. Further, the results are validated by comparing with previously published work.

Free convection and thermal radiation of nanofluid inside nonagon inclined cavity containing a porous medium influenced by magnetic field with variable direction in the presence of uniform heat generation/absorption

Purpose The purpose of this paper is to study the natural convection and radiation heat transfer inside Nonagon inclined cavity with variable heated source length, which contains a porous medium saturated with nanofluid in the presence of uniform heat generation or absorption under the effect of uniform magnetic field with variable direction. The shape factor of nano particles is taking account for the model of nanofluid. Design/methodology/approach This study is established in two-dimensional space. The 2D numerical study is effectuated with Comsol Multiphysics based on the on the finite element method. The 2D equation system is exposed on dimensionless form taking into account the boundary conditions. Findings Results obtained show that the convection heat transfer is ameliorated with the augmentation of heated source length. The convection heat transfer is enhanced by increasing Rayleigh, Darcy numbers and the heated source length; however, it is reduced by rising Hartmann number. The presence of radiation parameter lead to improve the convection heat transfer in the presence of both uniform heat generation/absorption. The average Nusselt number reaches a maximum for an inclination of cavity γ = 45° and a minimum for γ = 60°. Both the increase of the shape factor of nano particles and the solid fraction of nano particles improve the convection heat transfer. Originality/value Different studies have been realized to study the heat transfer inside cavity contains porous medium saturated with nanofluid under magnetic field effect. In this work, the Nonagon geometric of cavity studied has never been studied. In addition, the effect of radiation parameter with relation of the shape factor of nanoparticles in the presence of uniform heat generation/absorption on the heat transfer performance have never been investigated. Also, the effect of magnetic field direction with relation of the inclination cavity on heat transfer performance.

Numerical Simulation of Air Distribution of Lateral Supply and Return Pattern Affected by Indoor Heated Source Distribution Models

In this paper, the numerical simulation was adopted to explore indoor air distribution affected by three typical heated source distribution models, included spatially homogeneous heated source in the room, the heated source distributed evenly at the bottom and the local heated source at the bottom of the room. The characteristics of air distribution effected by three typical heated source models were studied in the air conditioning room with the pattern of lateral supply and return, the scope of rational arrangement in relatively comfortable environment of indoor personnel occupied zone was obtained. The result indicated that, the air distribution with the setting of the spatially homogeneous heated source pattern and the heated source distributed evenly at the bottom pattern were more satisfying than the setting of the local heated source at the bottom pattern.

Star formation rate in Holmberg IX dwarf galaxy

In this paper we use previously determined H? fluxes for dwarf galaxy Holmberg IX (Arbutina et al. 2009) to calculate star formation rate (SFR) in this galaxy. We discuss possible contaminations of H? flux and, for the first time, we take into account optical emission from supernova remnants (SNRs) as a possible source of contamination of H? flux. Derived SFR for Holmberg IX is 3:4 x 10-4M.yr-1. Our value is lower then in previous studies, due to luminous shock-heated source M&H 9-10, possible hypernova remnant, which we excluded from the total H? flux in our calculation of SFR.