Question

Each parcel in the Lagrangian formulation is tagged using __________

(a) time-dependent position vector

(b) time-independent position vector

(c) time-dependent velocity vector

(d) time-independent velocity vector

This question was addressed to me during an online interview.

My question is taken from Governing Equations in section Governing Equations of Fluid Dynamics of Computational Fluid Dynamics

Answer 1

The correct option is (b) time-independent position vector

To elaborate: The tag is time-independent so that the tag does not vary along with the flow. Position vector is chosen to follow the parcel along its position.