Natural convection in T-shaped cavities filled with water-based suspensions of COOH-functionalized multi walled carbon nanotubes

In the present study, natural convection fluid flow and heat transfer inside a T-shaped cavity filled with water-based suspensions of COOH-functionalized multi walled carbon nanotube has been numerically investigated. The considered cavity is a T-shaped enclosure having six walls at high constant temperature (Th) and a horizontal top wall at low temperature (Tc) while the bottom wall is kept thermally insulated. To carry out the numerical simulations, the governing equations are discretized employing the finite volume method (FVM) while the SIMPLER algorithm is used to couple velocity and pressure fields to solve governing mass, momentum, and energy equations. The effects of solid volume fraction from 0.0% to 1.0%, the aspect ratio between 0.2 and 0.8 of the T-shaped cavity and Rayleigh number range of 103 and 105 on the fluid flow and heat transfer inside the cavity are examined in details. According to the predicted results, the average Nusselt number increases (to 124%) with increase in the solid volume fraction of nanofluid and Rayleigh number for different aspect ratios. Also, at low Rayleigh number, Ra=103 or 104, the conduction dominates the transport phenomenon in the T-shaped cavity. Therefore, the average Nusselt number decreases with an increase in aspect ratio.