Question

What is the cause of cross-stream numerical diffusion?

(a) One-dimensional nature of the assumed profiles

(b) Multi-dimensional nature of the assumed profiles

(c) Higher order of accuracy

(d) Higher order of interpolation

This question was addressed to me in an internship interview.

My question is based upon Convection-Diffusion Problems in section Convection-Diffusion Problems of Computational Fluid Dynamics

Answer 1

Right option is (a) One-dimensional nature of the assumed profiles

The explanation is: One of the types of numerical diffusion errors is the cross-stream numerical diffusion. Cross-stream numerical diffusion is caused by the one-dimensional nature of interpolation when the grid is multi-dimensional. This is caused by cross-flow diffusion or false diffusion.