Ali Akbar Abbasian Arani

Free Convection in a Nanofluid Filled Square Cavity with an Horizontal Heated Plate

The natural convection in a square cavity with a heated horizontal plate containing a nanofluid (water and Ag) is simulated numerically. The heated plate and vertical walls are maintained at a constant temperature, Th and Tc, while the horizontal walls are adiabatic. The nanofluid is assumed to be incompressible and the flow is considered to be laminar. The continuity, momentum and energy equations written in terms of the primitive variables are discretized using a control volume approach and the SIMPLER algorithm. A parametric study is performed and the effect of the Rayleigh number, the location of the heated plate and the volume fraction of the nanoparticles on the fluid flow and the heat transfer inside the cavity are investigated. The results show that the mean Nusselt number of the vertical walls increases with increasing the volume fraction of the nanoparticles. Moreover, for a constant volume fraction of the nanoparticles, the Nusselt number of the vertical walls decreases substantially as the location of the heated plate varies from top to bottom of the cavity.

Determining the Optimum Arrangement of Micromixers in a Microchannel Filled with CuO-Water Nanofluid via Minimizing Entropy Generation

In this study, the flow of CuO-water nanofluid in a parallel-plate microchannel in the presence of several micromixers is examined to find optimum arrangements of the micromixers. The governing equations, which are accompanied with the slip velocity and temperature jump boundary conditions, are solved by the Finite Volume Method and SIMPLER algorithm. The study is conducted for the Reynolds numbers in the range of 10 ≤ Re ≤ 100, Knudsen numbers ranging of 0 ≤ Kn ≤ 0.1 and volume fraction of nanoparticles ranging of 0 ≤ ϕ ≤ 4%. The results show that the optimum arrangements of the micromixers belong to cases in which the heights of micromixers are smaller, the distance between them is lower, and their numbers are more.

MIXED CONVECTION OF FUNCTIONALIZED DWCNT/WATER NANOFLUID IN BAFFLED LID-DRIVEN CAVITIES

The present study aims to evaluate the mixed convection flow and heat transfer of functionalized DWCNT/water nanofluids with variable properties in a cavity having hot baffles. The investigation is performed at different nanoparticles volume fraction including 0, 0.0002, 0.001, 0.002, and 0.004, Richardson numbers ranging from 0.01 to 100, inclination angles ranging from 0 to 60° and at constant Grashof number of 104. The results presented as streamlines and isotherms plot and Nusselt number diagrams. According to the finding with increasing nanoparticles volume fraction and distance between the left hot baffles of nanoparticles average Nusselt number enhances for all considered Richardson numbers and cavity inclination angles. Also with increasing Richardson number, the rate of changes of average Nusselt number increase with increasing distance between the left hot baffles. For example, at Richardson number of 0.01, by increasing L1 from 0.4 to 0.6, the average Nusselt number increases 7%; while for similar situation at Richardson number of 0.1, 1.0, and 10, the average Nusselt number increases, respectively, 17%, 24%, and 26%. At all Richardson numbers, the maximum value of average Nusselt number is achieved for a minimum length of left baffles. This article has been corrected. Link to the correction 10.2298/TSCI190203032E

Numerical Comparison of Two and Three Dimensional Flow Regimes in Porous Media

The purpose of this work is to study the fluid flow regimes in a porous media with high enough velocities (in the range of laminar flow). In our study, the results obtained from expanding Darcy’s equation to Forchheimer’s equation with volume averaging method have been used for studdying the fluid flow behavior in 2D and 3D models. Results of numerical simulations show that in all cases, there are weak inertial regime, strong inertial regime and transition zone. In all the cases, the domain of weak inertial regime is relatively narrow, and this problem is intensified in the 3D numerical simulations. This could be the reason of missing the weak inertial regime in experimental studies on inertial fluid flow in porous media. The domain of strong inertial regime in 3D models is so wide that after Darcy’s regime, the governed regime is the strong inertial regime. To obtain more accurate and analytical results, more studies should be done on the 2D and the 3D flow regimes.