- A solid body in a steadily moving, inviscid (and incompressible) fluid does experience no drag. That’s fine! However, a drag must appear when, by reversing the process, we observe the steadily moving body through the fluid at rest. Otherwise, who pays for irreducible non-steady motions which take place locally with the passage of the body? How can these two facts be brought together?
- The explanation deals with an irreversible process: while a steadily moving fluid spontaneously embeds a body at rest, the reverse requires an external source of work (per unit time). This because, as shown by bernoulli613, the boundary of the body at rest becomes also a source of vorticity for the moving fluid. Can we say alike for Faraday’s Paradox on electromagnetic induction?
Tags: d'Alembert, electromagnetic, Faraday, vorticity
