The criteria for stability of the FTCS numerical scheme for the heat equation is given by

The stability criteria for the Forward Time Central Space (FTCS) numerical scheme for the heat equation is given by the condition that the Courant number must be less than or equal to 0.5. This is mathematically represented as:

Δt ≤ (Δx)² / (2α)

where:

• Δt is the time step,
• Δx is the spatial step, and
• α is the thermal diffusivity of the material.

This condition ensures that the numerical solution does not grow unbounded with time, which would indicate an unstable solution. If this condition is not met, the numerical solution may not accurately represent the physical system.