Tumbling elimination induced by permeability: an experimental approach

TL;DR

This study experimentally investigates how permeability and porosity influence the falling behaviors of porous plates, revealing that increased porosity stabilizes descent and eliminates tumbling through circulation reduction.

Contribution

It introduces an experimental approach to analyze how permeability and porosity affect falling regimes, highlighting the stabilizing effect of porosity on tumbling behavior.

Findings

Porosity stabilizes falling regimes and eliminates tumbling.

Decreased circulation due to holes stabilizes trajectories.

Permeability and porosity systematically influence falling behaviors.

Abstract

Archetypal falling behaviors of impervious objects are classified into four modes: fluttering, tumbling, steady descent and chaotic motion. The classical scenario predicts these behaviors to be affected by two dimensionless quantities: dimensionless inertia and Reynolds number. In this article we explore experimentally the effect of permeability and porosity on the falling regimes of porous plates. By drilling several hole distributions in rectangular plates, both permeability and porosity are varied systematically. We discover that the introduction of porosity affects the stability of the falling regimes eliminating tumbling. Using a phenomenological model we show that a decrease in circulation induced by the introduction of holes is the primary mechanism for stabilizing the plates' trajectories.