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Transient free convection about a vertical flat plate embedded in a porous medium. (English) Zbl 0539.76088
The authors adopt the boundary layer equations for a Darcian fluid and they assume a representation of temperature by means of the complementary error function depending on the nondimensional boundary layer thickness $$\Delta$$. This yields a hyperbolic partial differential equation for $$\Delta$$ which is solved (a) by use of the method of characteristics and (b) approximately by use of an integral method. This is carried out for a step increase in the spatially constant wall temperature or wall heat flux. Authors discuss results for the transient change of $$\Delta$$ and the approach of the steady state.