Question

When compared to the algorithm to calculate the gradient of a structured grid, the algorithm for unstructured grids ___________

(a) need more computational cost

(b) need less computational cost

(c) is more accurate

(d) is less accurate

This question was posed to me in exam.

My doubt stems from FVM topic in portion Finite Volume Methods of Computational Fluid Dynamics

Answer 1

The correct choice is (b) need less computational cost

Easy explanation: Accuracy wise, both the grids result in the same level of accuracy as they do not involve any approximation. But, the unstructured grid algorithm needs less computational cost as it is written in terms of the global indices. This can be adopted for structured grids also.