The minimum-enstrophy principle for decaying 2D turbulence in circular domains

In several numerical and experimental studies [1, 2] on freely evolving or decaying two-dimensional (2D) turbulence on a square bounded domain it is observed that a flow, initially containing no net angular momentum (L), spontaneously acquires angular momentum by flow-wall interaction. From earlier work, by Li and Montgomery [3], it could be conjectured that on a circular domain with a no-slip boundary angular momentum production is absent. Decaying turbulence experiments in stratified fluids conducted a few years later by Maassen et al. [4] provided additional evidence supporting this conjecture. These observations have recently been confirmed by Schneider and Farge [5] for decaying 2D turbulence with substantially higher initial integral scale Reynolds numbers