A new model to calculate heat eddy diffusivity in separating and reattaching flows based on modification of constant Prt is proposed. This modification is made using an empirical correlation between maximum Nusselt number and entrance Reynolds number. The model includes both the simplicity of Prt=0.9 assumption and the accuracy of two-equation heat-transfer models. Furthermore, an appropriate l...

in this work, the steady and laminar mixed convection of nanofluid in horizontal concentric annulus withrotating inner cylinder is investigated numerically. the inner and outer cylinders are kept at constanttemperature ti and to respectively, where ti>to. the annular space is filled with alumina-water nanofluid.the governing equations with the corresponded boundary conditions in the polar coord...

in recent years, impinging streams have received increasing interest for their high efficiency in heat and mass transfer. this numerical study was conducted to investigate flow and heat transfer characteristics of one-way opposing jets of non-newtonian fluids. effects of reynolds number impinging angle, momentum ratio and flow behavior index on mixing index were evaluated. the results showed im...

in this paper, the flow around bluff bodies with different cross sections and determination of forces acts on them are investigated.this paper presents the results of a numerical study on the flow characteristics and heat transfer over two equal square cylinders in a tandem arrangement. spacing between the cylinders is 5 widths of the cylinder and the reynolds number ranges from 1 to 200, pr=0....

The thermo-hydraulic behavior of the air flow over a two dimensional ribbed channel wasnumerically investigated in various rib-width ratio configurations (B/H=0.5-1.75) atdifferent Reynolds numbers, ranging from 6000 to 18000. The capability of differentturbulence models, including standard k-ε, RNG k-ε, standard k-ω, and SST k-ω, inpredicting the heat transfer rate was compared with the experi...

The previous studies of authors on passive micromixers indicated that the micromixers dividing the flow to several layers, such as rhombus micromixers and micromixers with obstacles in the middle of the mixing channel, have higher mixing degree than other types. Also, using of oscillatory inlet velocities is an active method to enhance the mixing efficiency of micromixers. Therefore, in this st...

this paper presents results of a numerical study of mixed convection and entropy generation of cu–water nanofluid in a square ventilating cavity at different inclination angles. except a piece of bottom wall with a uniform heat flux, all of the cavity walls are insulated. the inlet port is placed at the bottom of the left wall and the outlet port is positioned at the top of the right wall. entr...