t$/$L$,$ the base boundary condition is a constant temperature Tb the only cooling mechanism with $$ and T$\backslash$infty $.$Concave fin:

Let me show you a different form of the fin equation:

$\frac{d}{dx}[k{A}_c(x)\frac{dT}{dx}]-\frac{d{A}_s(x)}{dx}h(T-T_{})=0$

where $A_s(x)=dx\sqrt[\phantom{2}]{1+[f^{\text{'}}(x){]}^2}$ is the local surface

area where convection occurs, and $f(x)$ is the function

that defines the fin's shape. Use this equation and the

fin's slenderness condition as a simplification.