Experimental investigation of twin pulsed jets in a hemispheric elastic cavity

TL;DR

This experimental study investigates how the spacing and strength of twin pulsed jets affect fluid dynamics within an elastic hemispherical cavity, revealing complex vortex behaviors relevant to cardiac flows.

Contribution

It provides new experimental insights into twin pulsed jet interactions in elastic environments, highlighting flow regimes and vortex behaviors with implications for cardiovascular fluid dynamics.

Findings

Identified three distinct flow regimes: decay, wall rebound, and secondary vortex formation.

Observed symmetry breaking and trajectory shifts in twin vortex rings.

Revealed wall-induced rebound mechanisms affecting vortex dynamics.

Abstract

This study experimentally examines the impact of spacing between two pulsed jets and their strengths on the fluid dynamics within an elastic hemispherical cavity. Such interactions between multiple pulsed jets are observed in various natural and industrial contexts, including cardiovascular flows, where they occur naturally within the atria or result from medical interventions (e.g., mitral valve repair, mechanical heart valves, paravalvular leaks) or diseases (e.g., aortic or pulmonary valve regurgitation). Fundamentally, these flows usually feature two or more pulsed jets interacting in an expanding, elastic environment. In this investigation, the experimental setup features two parallel pulsed jets entering the cavity, with jet strength varied across five formation times (1, 2, 3, 4, 5) and four spacing ratios (1.5, 2.0, 2.5, 3.0). Time-resolved particle image velocimetry is used to capture the instantaneous velocity fields. The results reveal three distinct flow regimes: short-time decay, decay at the wall, and wall rebound with or without the formation of secondary vortices. These findings uncover rare aspects of twin vortex ring behavior, including symmetry breaking, trajectory shifts, and wall-induced rebound mechanisms, with direct relevance to cardiac fluid dynamics in both healthy and pathological conditions.