Question

When is the Richardson extrapolation accurate?

(a) When the system is stable

(b) When the convergence is monotonic

(c) When the system is consistent

(d) When the system is linear

The question was asked in an interview.

My doubt stems from Errors in Finite Difference Approximations topic in division Finite Difference Methods of Computational Fluid Dynamics

Answer 1

The correct choice is (b) When the convergence is monotonic

Explanation: The Richardson extrapolation is very useful as it is a simple method. But, it can give accurate results only when the convergence is monotonic. This convergence represents the convergence of error while refining the grid.