
Computer Simulations and Thermal Design 361
The stability criteria for this equation is
(14.36)
To demonstrate this, consider a plane wall with an initial temperature of 50°C whose
left and right side temperatures are suddenly changed to 200°C. Let’s use only
three nodes; one interior node and one at each side as shown in Figure 14.3. The
T
1
= T
3
= 200°C and T
2
has to be calculated as a function of time. It is obvious that
T
2
will increase from 50°C to the equilibrium value of 200°C and can not go higher
than that. Figure 14.3 shows that
If Fo• > 1, T
2
oscillates back and forth around the equilibrium value ...