Chaotic advection in a recirculating flow: Effect of a fluid multiple-flexible-solid interaction.

Area of Science:

• Fluid dynamics
• Nonlinear dynamics
• Computational physics

Background:

• Chaotic advection is crucial in mixing and transport phenomena.
• Understanding fluid-solid interactions is key for complex flow systems.
• Previous studies focused on single solid interactions, leaving multi-solid dynamics unexplored.

Purpose of the Study:

• Investigate chaotic advection in a 2D laminar lid-driven cavity flow.
• Analyze the two-way interaction between multiple flexible elliptical-solids and the fluid.
• Explore how the number of solids influences fluid and solid motion, deformation, and chaotic advection.

Main Methods:

• Simulated fluid-multiple-flexible-solid interaction (FMSI) with varying numbers of solids (N=1-120).
• Employed Adaptive Material Tracking (AMT) for visualizing fluid and solid dynamics.
• Utilized Finite-Time Lyapunov Exponent (FTLE) for quantitative analysis of chaotic advection.

Main Results:

• Fluid and solid motion/deformation transition from periodic (N≤10) to aperiodic (N>10) states.
• Chaotic advection initially increases with N (up to N=6) then decreases (N=6-10) in periodic states.
• Chaotic advection shows an asymptotic increase with N (up to N=120) in transient states.
• Chaos signatures include interface growth (AMT) and Lagrangian coherent structures (FTLE).

Conclusions:

• The number of flexible solids significantly impacts chaotic advection.
• A novel technique using multiple deformable solids can enhance chaotic advection.
• Findings are relevant to applications requiring controlled mixing and transport.