Question

The numerical diffusion and numerical anti-diffusion terms are equal for the first-order Euler scheme are equal in magnitude when __________

(a) the courant number of diffusion is equal to one

(b) the courant number of diffusion is equal to two

(c) the courant number of convection is equal to one

(d) the courant number of convection is equal to two

This question was addressed to me in examination.

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

Answer 1

Right choice is (c) the courant number of convection is equal to one

The best I can explain: The numerical diffusion term of the first-order implicit Euler scheme and numerical anti-diffusion term of the first-order explicit Euler scheme are equal in magnitude and opposite in sign when the courant number of convection is equal to one.