Computer Simulation Study of Collective Phenomena in Dense Suspensions of Red Blood Cells under Shear

1. Front Matter

   Pages i-xiii

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2. Introduction

   1. Front Matter

      Pages 3-3

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   2. Motivation, aims, and outline of the thesis

      • Timm Krüger

      Pages 1-2

   3. Introduction to complex fluids and their rheology

      • Timm Krüger

      Pages 5-10

   4. Introduction to the physics of red blood cells and hemorheology

      • Timm Krüger

      Pages 11-14

3. Numerical model for simulations of red blood cell suspensions

   1. Front Matter

      Pages 15-15

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   2. Physical considerations and ingredients for the numerical model

      • Timm Krüger

      Pages 17-19

   3. Fluid solver: the lattice Boltzmann method

      • Timm Krüger

      Pages 21-36

   4. Fluid-structure interaction: the immersed boundary method

      • Timm Krüger

      Pages 37-42

   5. Membrane model and energetics

      • Timm Krüger

      Pages 43-48

   6. Advanced model discussions

      • Timm Krüger

      Pages 49-69

4. Simulation results and interpretation

   1. Front Matter

      Pages 71-71

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   2. Stress evaluation in combined immersed boundary lattice Boltzmann simulations

      • Timm Krüger

      Pages 73-84

   3. Rheology and microscopic behavior of red blood cell suspensions

      • Timm Krüger

      Pages 85-120

   4. Conclusions and outlook

      • Timm Krüger

      Pages 121-126

5. Back Matter

   Pages 127-165

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The rheology of dense red blood cell suspensions is investigated via computer simulations based on the lattice Boltzmann, the immersed boundary, and the finite element methods. The red blood cells are treated as extended and deformable particles immersed in the ambient fluid. In the first part of the work, the numerical model and strategies for stress evaluation are discussed. In the second part, the behavior of the suspensions in simple shear flow is studied for different volume fractions, particle deformabilities, and shear rates. Shear thinning behavior is recovered. The existence of a shear-induced transition from a tumbling to a tank-treading motion is demonstrated. The transition can be parameterized by a single quantity, namely the effective capillary number. It is the ratio of the suspension stress and the characteristic particle membrane stress. At the transition point, a strong increase in the orientational order of the red blood cells and a significant decrease of the particle diffusivity are observed. However, the average cell deformation shows no signature of the transition.

• Blood Rheology
• Direct Numerical Simulation
• Immersed Boundary Method
• Lattice Boltzmann Method
• Red Blood Cell Suspensions

• Düsseldorf, Germany

  Timm Krüger

Timm Krüger is physicist with focus on computational modeling of complex fluids at the Department of Applied Physics, Eindhoven University of Technology.

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