科研之友
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摘要
The free convection boundary-layer flow near a stagnation point in a porous medium is considered when there is local heat generation at a rate proportional to (T - T (a)) (p) , (p a parts per thousand yen 1), where T is the fluid temperature and T (a) the ambient temperature. Two cases are treated, when the surface is thermally insulated and when heat is supplied at a constant (dimensionless) rate h (s) from the boundary. If h (s) = 0 the solution approaches a nontrivial steady state for time t large in which the local heating has a significant effect when p a parts per thousand currency sign 2. For p %26gt; 2 the effects of the local heating become increasingly less important and the solution dies away, with the surface temperature being of O(t (-1)) for t large. When h (s) %26gt; 0 and there is heat input from the surface, the solution for p a parts per thousand currency sign 2 again approaches a nontrivial steady state for t large and all h (s) . For p %26gt; 2 there is a critical value h (s,crit) (dependent on the exponent p) of h (s) such that the solution still approaches a nontrivial steady state if h (s) %26lt; h (s,crit). For h (s) %26gt; h (s,crit) a singularity develops in the solution at a finite time, the nature of which is analysed.
- 出版日期2013-4
