Numerical study of natural convection of biological nanofluid flow prepared from tea leaves under the effect of magnetic field

Abstract

The heat transfer of a biological nanofluid (N/F) in a rectangular cavity with two hot triangular blades is examined in this work. The properties used for nanoparticles (N/Ps) are derived from a N/P prepared naturally from tea leaves. Silver N/Ps are distributed in a 50–50 water/ethylene glycol solution. The cavity’s bottom wall is extremely hot, while the upper wall is extremely cold. The side walls are insulated, and the enclosure is surrounded by a horizontal magnetic field (M/F). The equations are solved using the control volume technique and the SIMPLE algorithm. Finally, the Nu is determined by changing the dimensions of the blade, the Rayleigh number (Ra), and the Hartmann number (Ha). Finally, a correlation is expressed for the Nu in the range of parameter changes. The results demonstrate that an increment in the Ra from 103 to 105 enhances the Nu more than 2.5 times in the absence of an M/F. An enhancement in the strength of the M/F, especially at the Ra of 105, leads to a dramatic reduction in the Nu. An increase in the height of the triangular blade intensifies the amount of Nu in weak and strong convection. The enlargement of the base of the triangular blade first enhances and then decreases as the Nu. The addition of 5% silver biological N/Ps to the fluid enhances the Nu by 13.7% in the absence of an M/F for high Ras.