Question

The least-square method is ____________

(a) at least first-order accurate

(b) at least second-order accurate

(c) first-order accurate

(d) second-order accurate

This question was posed to me in an internship interview.

My doubt is from Diffusion Problem topic in chapter Diffusion Problem of Computational Fluid Dynamics

Answer 1

Correct choice is (a) at least first-order accurate

For explanation: The accuracy of the gradient found using this method is at least first-order. This can be proved by expanding the values of the flow variable using the Taylor series. It can be of higher orders also.