20 research outputs found

    Effect of tube diameter and capillary number on platelet margination and near-wall dynamics

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    The effect of tube diameter DD and capillary number CaCa on platelet margination in blood flow at ≈37%\approx 37\% tube haematocrit is investigated. The system is modelled as three-dimensional suspension of deformable red blood cells and nearly rigid platelets using a combination of the lattice-Boltzmann, immersed boundary and finite element methods. Results show that margination is facilitated by a non-diffusive radial platelet transport. This effect is important near the edge of the cell-free layer, but it is only observed for Ca>0.2Ca > 0.2, when red blood cells are tank-treading rather than tumbling. It is also shown that platelet trapping in the cell-free layer is reversible for Ca≀0.2Ca \leq 0.2. Only for the smallest investigated tube (D=10ÎŒmD = 10 \mu\text{m}) margination is essentially independent of CaCa. Once platelets have reached the cell-free layer, they tend to slide rather than tumble. The tumbling rate is essentially independent of CaCa but increases with DD. Tumbling is suppressed by the strong confinement due to the relatively small cell-free layer thickness at ≈37%\approx 37\% tube haematocrit.Comment: 16 pages, 10 figure
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