Derive the nodal equation corresponding to convection boundary node $(T_{\text{m}\text{i}\text{n}})$

$\frac{\text{d}\text{e}\text{l}\text{T}}{\text{d}\text{e}\text{l}\text{T}}=a(\frac{de{l}^{2}T}{del{x}^2}+\frac{de{l}^{2}T}{del{y}^2}),T=>$ temp $d=>$ thermal difussivity

$t=>$ time $x$&$y=>$ cordinates

$\frac{\text{d}\text{e}\text{l}\text{T}}{\text{d}\text{e}\text{l}\text{T}}=a(\frac{de{l}^{2}T}{del{x}^2}+\frac{de{l}^{2}T}{del{y}^2})+h(T_{}-T)$