At cellular scales (Re ~ 10⁻⁴–10⁻²) viscous forces dominate inertia. Time-reversibility of Stokes flow imposes Purcell's scallop theorem: reciprocal motions produce zero net displacement. Bacterial flagella and cilia evade it via…
At cellular scales (Re ~ 10⁻⁴–10⁻²) viscous forces dominate inertia. Time-reversibility of Stokes flow imposes Purcell's scallop theorem: reciprocal motions produce zero net displacement. Bacterial flagella and cilia evade it via…