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Locomotion by tangential deformation in a polymeric fluid
Lailai Zhu1, Minh Do-Quang, Eric Lauga
1Linné Flow Centre, KTH Mechanics, Stockholm, Sweden.
Summary
Cell locomotion in polymeric fluids is slower than in Newtonian fluids, but swimming efficiency increases. Polymeric stresses create an elastic wake, impacting flow profiles and velocity decay.
Area of Science:
- Fluid dynamics
- Biophysics
- Polymer physics
Background:
- Cell locomotion often occurs in complex polymeric fluids.
- Understanding locomotion in these non-Newtonian fluids is crucial for biological processes.
Purpose of the Study:
- To investigate the effects of polymeric fluids on self-propelled body locomotion.
- To analyze swimming velocity, work rate, and efficiency in Giesekus fluids.
Main Methods:
- Three-dimensional numerical simulations of a self-propelled body (squirmer) in a Giesekus fluid.
- Analysis at low Reynolds number and varying Weissenberg numbers.
Main Results:
- Swimming velocity decreases in polymeric fluids, with minimums at Weissenberg numbers of order 1.
- Swimming efficiency increases, despite higher work rates compared to Newtonian solvents.
- Polymeric stresses create a negative elastic wake, altering flow symmetry and increasing with Weissenberg number.
Conclusions:
- Polymeric fluids significantly alter cell locomotion dynamics, enhancing efficiency but reducing speed.
- The elastic wake and polymer stretching are key factors influencing flow profiles and velocity decay.
- Slender swimmers exhibit reduced polymer stretching and higher hydrodynamic efficiency.
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