Question

Which of these coordinate systems will best suit to model the flow in a pipe with a swirl?

(a) Cylindrical coordinates

(b) Cartesian coordinates

(c) Spherical coordinates

(d) Polar coordinates

This question was addressed to me in class test.

Asked question is from Numerical Methods in portion Numerical Methods of Computational Fluid Dynamics

Answer 1

Correct option is (a) Cylindrical coordinates

To explain I would say: In the case of flow over a pipe, cylindrical coordinates do the best as the dependent spatial variables are just 2 which would be 3 if it is Cartesian coordinates. But, in this case, a swirl component is included which makes the flow dependent on three dimensions anyway. To keep the complexities less, Cartesian coordinates should be chosen for this problem.