Question

The diagonal elements of the coefficient matrix obtained by applying the least-square to Cartesian grids are ___________

(a) the ratio of the grid sizes and the weights in the x, y, z-directions

(b) the product of the grid sizes and the weights in the x, y, z-directions

(c) the weights in the x, y, z-directions

(d) the grid sizes in the x, y, z-directions

I had been asked this question at a job interview.

I would like to ask this question from Diffusion Problem in portion Diffusion Problem of Computational Fluid Dynamics

Answer 1

Correct option is (d) the grid sizes in the x, y, z-directions

The best I can explain: The coefficient matrix obtained by applying the least-square to Cartesian grids has non-zero elements only in the diagonal. These non-zero elements are Δx, Δy and Δz (the grid sizes in the x, y, z-directions).