Numerical study of natural convection heat transfer in a trapeziform cavity filled with nanofluids

Abstract

The present research has intended numerically the steady of laminar natural convective flow and heat transfer in a trapeziform cavity filled with nanofluid. The heat transferring medium has been taken as water-ferrosopherric oxide (Fe3O4) and water-copper (Cu) nanofluids. The trapeziform cavity has been accurately propounded by uniformly heated bottom wall with two types of temperature distributions like constant temperature and sinusoidal temperature, constant temperature of cold top wall, adiabatic other two walls and no-slip condition of all walls. The governing partial differential equations for nanofluid have been transformed into the non-dimensional form using similarity transformation, then modified into finite element equations and finally solved. The influence of various values of the buoyancy parameter, Rayleigh number , Prandtl number nanoparticle volumetric ratio has been investigated numerically and described the results in this thesis. The results have been addressed and visually represented using streamlines and isothermal lines for velocity and temperature contours, as well as average Nusselt number for heat transfer rate. The Rayleigh number, Prandtl number and nanosolid volumetric ratio all have a substantial influence on the convective flow regime, and the value of average Nusselt number changes as these parameters change. Due to the greater value of the Rayleigh number , the average Nusselt number increases to 18.6% for sinusoidal temperature and 21.6% for constant temperature distribution at the hot bottom wall of the trapeziform enclosure using water-Fe3O4 nanofluid. The water-Fe3O4 nanofluid achieves a greater rate of heat transfer (5.83% for sinusoidal temperature and 7.38% for constant temperature distribution) than the base fluid (water). The solid volume fraction increases 0% to 3%, the mean Nusselt number increases 12.67% for sinusoidal temperature and 15.57% for constant temperature distribution using water-Cu nanofluid at the hot bottom wall of the trapeziform enclosure. Compared to water-Fe3O4 nanofluid, the Cu-water nanofluid achieves a greater rate of heat transfer 6.77% for sinusoidal temperature and 7.63% for constant temperature distribution at bottom wall using solid volume fraction .