Simulation of aggregating particles in complex flows by the lattice kinetic Monte Carlo method

Area of Science:

• Fluid dynamics
• Biophysics
• Computational modeling

Background:

• Particle aggregation in laminar flows is crucial in various scientific and engineering fields.
• Existing simulation methods often lack the ability to accurately model particle interactions under spatially varying shear rates.
• Understanding aggregation dynamics is key for applications ranging from industrial processes to biological systems.

Purpose of the Study:

• To develop and validate an efficient lattice kinetic Monte Carlo (LKMC) method for simulating particle aggregation in laminar flows with spatially varying shear rates.
• To incorporate a contact time model accounting for hydrodynamic interactions and their effect on collision efficiency.
• To investigate particle aggregation patterns in complex flow geometries, including parabolic flow and baffled systems.

Main Methods:

• Developed an efficient lattice kinetic Monte Carlo (LKMC) method.
• Incorporated a contact time model to describe particle-particle collision efficiency based on local shear rate (G) and approach angle (θ).
• Validated the model using experimental data for aggregating platelets in tube flow and simulated aggregation in parabolic and baffled flows.

Main Results:

• The developed collision efficiency model [ɛ=1 - ∫(0)(π/2) sinθ exp(-2cotθΓ(agg)/G)dθ] depends only on Γ(agg)∕G.
• For aggregating platelets, Γ(agg)=0.683 s(-1) accurately predicts experimental collision efficiencies across physiological shear rates.
• Simulations revealed distinct aggregate formation patterns in parabolic and baffled flows, with maximal aggregation rates in intermediate regions or vortices, respectively.

Conclusions:

• The validated LKMC method provides an efficient tool for simulating particle aggregation in complex laminar flows.
• The contact time model successfully accounts for hydrodynamic interactions influencing collision efficiency.
• The study offers insights into aggregate formation in physiologically relevant flow conditions, such as those found in stenotic or valvular diseases.