Abstract
Continuum equations governing thermal nonequilibrium modeling of unsteady natural convection inside trapezoidal enclosures with the effects of thermal radiation and exponential variation of boundary conditions are developed. These equations account for such effects as interphase heat transfer coefficient effect, thermal radiation effect, modified conductivity ratio effect, and dimensionless time parameter effect. Finite difference method is employed to solve these equations, and comparisons with previous published works are presented. Numerical results for the flow and heat transfer for fluid and solid phases are obtained for various combinations of the physical parameters. Graphical and tabular results illustrating interesting features of the physics of the problem are presented and discussed.