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Large-scale simulations of concentrated emulsion flows
Alexander Z Zinchenko1, Robert H Davis
1Department of Chemical Engineering, University of Colorado, Boulder, CO 80309-0424, USA. zinchenk@spot.colorado.edu
Summary
A new hybrid simulation method enables large-scale studies of concentrated emulsion flows. This technique significantly speeds up calculations, making long-time simulations of deformable drops feasible for the first time.
Area of Science:
- Fluid dynamics
- Computational physics
- Materials science
Background:
- Simulating concentrated emulsions of deformable drops is computationally intensive.
- Existing boundary-integral methods struggle with large numbers of drops and long simulation times.
- Understanding phenomena like shear thinning and phase transitions requires accurate large-scale simulations.
Purpose of the Study:
- To introduce and validate a novel hybrid boundary integral and economical multipole (BI/EM) method for large-scale dynamical simulations of concentrated emulsions.
- To assess the computational efficiency and feasibility of the BI/EM method compared to standard boundary-integral techniques.
- To apply the method to investigate complex flow behaviors in concentrated emulsions, including shear flow, sedimentation, and motion through emulsions.
Main Methods:
- Development of a hybrid boundary integral and economical multipole technique.
- Large-scale dynamical simulations of concentrated emulsions with O(10^2)-O(10^3) deformable drops.
- Application to steady shear flow, sedimentation, and buoyancy-driven motion scenarios.
- Ensemble averaging and convergence studies for accuracy.
Main Results:
- The BI/EM method offers a 2-3 order of magnitude speedup per time-step, enabling long-time, large-scale simulations.
- In steady shear flow, phase transitions were observed at high concentrations (c ≈ 0.55).
- Sedimentation studies revealed specific concentration ranges (c ≈ 0.25) and viscosity ratios (λ = 0.1) leading to maximum instability.
- Convergent results for bubble/drop settling velocity were obtained for simulations with up to 800 drops.
Conclusions:
- The hybrid BI/EM method is a powerful and efficient tool for large-scale dynamical simulations of concentrated emulsions.
- The simulations provide critical insights into the complex behaviors of deformable drops in concentrated flows.
- This approach opens new avenues for studying phenomena previously inaccessible due to computational limitations.