Question

To find the values at the current time-step, the Crank-Nicolson scheme uses ___________

(a) t-Δt and t+Δ t steps

(b) t-Δ t and t-2Δ t steps

(c) t+Δ t and t+2Δ t steps

(d) t and t+Δt steps

I got this question in unit test.

I'm obligated to ask this question of Transient Flows topic in section Transient Flows of Computational Fluid Dynamics

Answer 1

Correct answer is (b) t-Δ t and t-2Δ t steps

The explanation: Like the forward Euler scheme, the Crank-Nicolson scheme also uses the older steps only to get the values at the current node. It uses the values at the previous step and at the step previous to it.