Question

Which is correct regarding the upwind scheme?

(a) Neither numerical dispersion nor numerical diffusion error arises

(b) Only numerical diffusion error arises

(c) Both numerical dispersion and numerical diffusion errors arise

(d) Only numerical dispersion error arises

I got this question at a job interview.

The query is from Convection-Diffusion Problems in chapter Convection-Diffusion Problems of Computational Fluid Dynamics

Answer 1

The correct answer is (c) Both numerical dispersion and numerical diffusion errors arise

To explain I would say: In the analysis for errors, while comparing the exact and numerical solutions, the first-order upwind scheme gives a complex k-value. Therefore, it will have both numerical dispersion and numerical diffusion problems.