A wall 0.12 m thick having a thermal diffusivity of 1.5u106 m2 /s is initially at a uniform temperature of 85qC. Suddenly one face is lowered to a temperature of 20qC, while the other face is...

A wall 0.12 m thick having a thermal diffusivity of 1.5u106 m2 /s is initially at a uniform temperature of 85qC. Suddenly one face is lowered to a temperature of 20qC, while the other face is perfectly insulated. (a) Using the explicit discontinuous finite element technique with space and time increments of 30 mm and 300 s, respectively, determine the temperature distribution at t = 45 min. (b) With 'x = 30 mm and 't = 300 s, compute T(x,t) for 0d td tss, where tss is the time required for the temperature at each nodal point to reach a value that is within 1qC of the steady state temperature. Repeat the foregoing calculation for 't = 75 s. For each value of 't, plot temperature histories for each face and the mid-plane.