In: Physics
A long solid bar (k = 28 W/m·K and α = 12 × 10−6 m2/s) of square
cross section is initially at a uniform temperature of 32°C. The
cross section of the bar is 20 cm × 20 cm in size, and heat is
generated in it uniformly at a rate of ??̇ = 8 × 105 ??⁄??2. All
four sides of the bar are subjected to convection to the ambient
air at T∞ = 30 °C with a heat transfer coefficient of h = 45
W/m2·K. Using the explicit finite difference method with a mesh
size of Δx = Δy = 10 cm, the centerline temperature after 20
minutes is desired. (a) Obtain the finite-difference nodal
equations required to solve this problem and (b) Determine the
upper limit of the time step that can be used to ensure numerical
stability of the explicit finite-difference solution.
Do not solve fo the temperatures. Only construct the nodal
equations and determine the limit on ∆t.