Heat transfer optimization on convective flow of various fluids inside an enclosure with curved heat source

In this work, the efficiency of thermo-fluidic thermal performance is numerically extrapolated on the incompressible natural convection flow of three fluids (mercury, air, and water) inside an enclosure with a curved heat source. The governing equations are presented in the Cartesian coordinate system and solved using the stream function-vorticity technique with second-order finite difference approach. The fluid movement and thermal transport features are represented in terms of local and average Nusselt numbers, as well as streamlines and isotherms for the considered fluids with various strengths of buoyancy force. Results explore that water with high buoyancy force produce the highest local and mean heat transmission rates. When the strength of buoyancy force is low, the local Nusselt number enhances linearly for all the considered fluids, whereas the variation is nonlinear when the strength of buoyancy force is high. When the strength of buoyancy force is high $$(Ra=10^6)$$, the mean heat transfer rate within the enclosure can be enhanced up to $$66.5\%$$ by replacing the working fluid mercury with water. The best heat transfer efficiency can be achieved with water among mercury, air, and water.