Lattice Boltzmann method for mixed convection of nanofluid two-phase flow in a trapezoidal-shaped sinusoidal cavity by considering Brownian motion

Abstract

The lattice Boltzmann method is used to explore the mixed convection of nanofluid within an inclined trapezoidal cavity in the presence of a magnetic field in multiple directions. The trapezoidal-shaped cavity's sides are adiabatic, with the top movable wall cold and the bottom wall sinusoidally heated. The temperature and flow distribution functions are used in the simulations to calculate all of the parameters linked to the flow and temperature fields. The effects of different Rayleigh numbers (Ra = 103, 104, and 105), Richardson numbers (Ri = 0.1, 1, and 10), inclined cavity angles (θ= 0°-90°), volume fractions of nanoparticles (ϕ= 0–3 percent), magnetic field intensity (Ha = 0–100), and applied magnetic field angle (γ= 0°-90°) on heat transfer, streamlines, isothermal lines, and average Nusselt number on the hot wall were studied. According to the results, heat transfer improves with a larger Rayleigh number and a smaller Richardson number. As a corollary, raising the volume fraction of nanoparticles while keeping all other variables constant leads to a higher average Nusselt number. By reducing the flow speed within the hollow, heat transfer is reduced when the Hartmann number is increased. Altering the cavity's slope and the magnetic field's angle also has an effect on the flow and heat transfer. Applying a magnetic field has a more pronounced impact on heat conduction; although the effect of doing so at Ra=103 is comparable to 1% (when Ha=100 is used), for Ra=104 and 105, it is equivalent to 17% and 44%, respectively. As the Hartmann number is increased from 0 to 100, the Nuavg drops from 20 to 5 (a reduction of 4%) in the case of Ri= 0.1, 1, and 10.