A meticulous study of aspect ratio impacts on flow and heat of nanofluid in a cavity: Finite difference-based computations.

The phenomenon of natural convection in rectangular cavities of different aspect ratios is considered. The water is considered a base fluid associated with copper nanoparticles. The flow is induced only due to buoyancy force that arises by heating the right side of the cavity. The left side is set cold while the other walls are assumed to be at zero flux temperature. The governing equations of the present communication are simulated by the finite difference method. This study explores the impacts of Rayleigh number (Ra), Prandtl number (Pr), nanoparticles volume fraction (ϕ), and aspect ratio (A). Different combinations of these parameters are investigated. Compared to other parameters, Rayleigh number (10 4 < Ra < 1 0 8 ), aspect ratio (1 ≤ A ≤ 3), and volume fraction of nanoparticles (0. 0 1 ≤ ϕ ≤ 0. 1), A is found more effective on the flow field and isotherms. Regression curves are determined for the mean Nusselt number (Nuavg) as a function of Ra for different cases. It is found that Nuavg more precisely fits the exponential function. Also, it is found that Nuavg decreases as the values of A increase. But, ϕ , shows the opposite behavior. It is noticed that when the A of the cavity grows, so does the mean heat transfer Nu. With rising Ra, the local heat transfer NuL decreases and the heat transfer rises. In the case of the square cavity, the regression coefficient for Nuavg is found to be 0.3673 and 0.2514 for an exponential function. [ABSTRACT FROM AUTHOR]