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The main objective of the study is to investigate the fluid flow pattern and thermal behavior of time-dependent 2-dimensional lid-driven cavity flow in the presence of mixed convection. The square-shaped lid-driven chamber was filled with a nanofluid consisting of carbon nanotubes (CNT) dispersed in kerosene oil. A semicircular heater is positioned along the lower wall. The research also incorporates the examination of magnetohydrodynamics and radiation. The use of the Galerkin residual approach inside the finite element method is utilized to derive nonlinear dimensionless governing equations. The phenomenon of Brownian motion in nanoparticles is included into models that describe thermal conductivity and dynamic viscosity. A constant magnetic field with a magnitude of Ha = 10, a constant Reynolds number of Re = 100, and a constant radiation parameter of Rd = 1 were selected for the study. Additionally, a nanofluid concentration of 5 % was chosen. The study aims to investigate the impact of mixed convection by using variable Richardson numbers within the range of 0.1 ≤ Ri ≤ 10. The results are presented in the form of streamlines, isotherms, 2D and 3D charts, illustrating the temporal variations of diverse thermophysical parameters. The investigation reveals that the magnitudes of the drag force and pressure gradient are comparatively greater in the scenario of natural convection. The drag force is 2.8 times greater in the Ri=10 case compared to the Ri=0.1 case. The velocity magnitude is found to be 18 times higher in the Ri= 10 case than in the Ri= 1 case. The Nusselt number has an elevated value as the Richardson number is augmented in conjunction with the dimensionless time (τ).

Computational results for steady laminar flow of three different shear thinning fluids lid-driven square cavity are presented. The viscoelastic nature of the fluids is represented by linear and exponential Phan-Thien Tanner (PTT) and Giesekus constitutive models. Computations are based on finite volume technique incorporating non-uniform collocated grids. The stress terms in the constitutive equations are approximated by higher-order and bounded scheme of Convergent and Universally Bounded Interpolation Scheme for the Treatment of Advection (CUBISTA). Effects of the elasticity, inertia as well as constitutive model parameters on the stress and velocity fields, size and intensity of the primary and secondary vortexes are investigated and discussed in detail. Moreover highly accurate benchmark numerical solutions are provided for each considered constitutive model. [ABSTRACT FROM AUTHOR]

Abstract: A numerical investigation of laminar mixed convection flows through a copper–water nanofluid in a square lid-driven cavity has been executed. In the present study, the top and bottom horizontal walls are insulated while the vertical walls are maintained at constant but different temperatures. The study has been carried out for the Rayleigh number 104 to 106, Reynolds number 1 to 100 and the solid volume fraction 0 to 0.05. The thermal conductivity and effective viscosity of nanofluid have been calculated by Patel and Brinkman models, respectively. The effects of solid volume fraction of nanofluids on hydrodynamic and thermal characteristics have been investigated and discussed. It is found that at the fixed Reynolds number, the solid concentration affects on the flow pattern and thermal behavior particularly for a higher Rayleigh number. In addition it is observed that the effect of solid concentration decreases by the increase of Reynolds number. [Copyright &y& Elsevier]