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A drag force interpolation model for capsule-shaped cells in fluid flows near a surface
Krister Wiklund1, Hanqing Zhang1, Tim Stangner1
1Department of Physics, Umeå University, 901 87 Umeå, Sweden.
Microbiology (Reading, England)
|March 7, 2018
Summary
We developed a new model to accurately calculate hydrodynamic forces on tethered cells in microfluidic flows. This model improves upon existing methods for estimating forces on bacteria like Escherichia coli.
Area of Science:
- Fluid dynamics
- Biophysics
- Computational biology
Background:
- Accurately calculating hydrodynamic forces on cells in microfluidic flows is crucial for understanding cell behavior and adhesion.
- Existing models often rely on simplified geometries or approximations, potentially leading to inaccuracies in force estimation.
Purpose of the Study:
- To develop and validate a novel interpolation model for calculating hydrodynamic forces on tethered, capsule-shaped cells near a surface.
- To compare the accuracy of the new model against existing approximations, particularly for Escherichia coli cells.
Main Methods:
- Numerical solutions of the Navier-Stokes equations for capsule-shaped objects.
- Interpolation model development based on geometric parameters (aspect ratio, orientation).
- Validation against computational fluid dynamics simulations and established approximations (e.g., Goldman approximation).
Main Results:
- The interpolation model achieved high accuracy (<0.15% average error) compared to CFD simulations for aspect ratios up to 5.
- The model precisely reproduced the Goldman approximation for spherical objects near a surface.
- Using a capsule shape for Escherichia coli yielded a 4.4% better fit than an ellipsoid, resulting in a 15% difference in hydrodynamic force.
Conclusions:
- The developed interpolation model offers a fast, accurate, and computationally efficient alternative to complex fluid dynamics simulations.
- The model provides significantly improved agreement for hydrodynamic force estimation compared to commonly used approximate models.
- This tool is valuable for bacterial adhesion experiments and includes a MATLAB script for cell tracking and force estimation.
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