Question

Why are isolines circular when the Peclet number is zero?

(a) Fluid is flowing and diffusion spreads equally

(b) Fluid is stagnant and diffusion spreads equally

(c) Fluid is stagnant and diffusion spreads directionally

(d) Fluid is flowing and diffusion spreads directionally

This question was posed to me in an online interview.

My doubt is from Discretization Aspects in division Basic Aspects of Discretization, Grid Generation with Appropriate Transformation of Computational Fluid Dynamics

Answer 1

Right option is (b) Fluid is stagnant and diffusion spreads equally

To explain I would say: When the Peclet number is zero, the problem is dominated by diffusion. This means that the fluid is stagnant. Diffusion allows the flow of property to spread in the domain equally in all the directions.