Localised particle clustering triggers periodic leakage in a counter-rotating vortex pair

Multiscale vortex structures significantly influence inertial particle dynamics, contributing to clustering in turbulent flows – a phenomenon common in many applications. In this study, our primary objective is to investigate how particle clustering is influenced by vortex effects while accounting for particle feedback. Using a two-way coupled numerical method, we identify novel particle dynamics characteristics, as localised particle clustering triggers periodic leakage, even in a dilute particle-laden unequal-strength counter-rotating vortex pair (CVP). Small, heavy, dilute inertial particles are considered. In particular, the initial particle volume fraction and the particle Stokes number are set to upper Phi Subscript p comma 0 Baseline less than 1.0 times 10 Superscript negative 3 Φ p , 0 < 1.0 × 10 − 3 p,0< 1.0× 10⁻³ and italic St element of left parenthesis 0 comma 0.1 right parenthesis St ∈ ( 0 , 0.1 ) St∈ (0,0.1) , respectively. The particle dynamics is governed by two critical Stokes numbers: the trapping critical Stokes number italic St Subscript italic cr comma t St cr,t Stcr,t and the stability critical Stokes number italic St Subscript italic cr comma s St cr,s Stcr,s . The critical Stokes number italic St Subscript italic cr comma t St cr,t Stcr,t governs particle trapping. For italic St less than italic St Subscript italic cr comma t Baseline