Analysis of Transient Free Convection with Temperature Dependent Fluid Properties by an Integral Method : An Isothermal Vertical Flat Plate in the Air

Transient free convection from a vertical flat plate which is suddenly raised to a uniform higher temperature in a variable property fluid is treated by an integral method. Numerical results are compared with more precise solutions of the differential equations for the initial stage of motion in a constant property fluid and for steady state in a variable property fluid. The results show that present approximate solution gives a reasonable prediction of the transient free convection characteristics of the variable property fluid. The effects of the temperature dependent properties on the time which purely one-dimensional heat conduction is terminated and on the time required to reach steady state for each position along the plate is not so significant for the air.