Fig. 1: Updating the reduced-order model for compression.

a Flow chart of the process to calculate the values for \({X}_{0}^{{{{{{{{\rm{c}}}}}}}}}\) for RBC partitioning in compressed vessels. b Snapshot of a fully resolved cellular blood flow simulation. c Rotated snapshot of the same simulation to show compression has an elliptical cross-section. d Plasma skimming curve. Green points are from varying the flow ratio in a bifurcation geometry of 33 μm with a compression before the bifurcation and an inlet haematocrit of 20%. Compares how well the original phase separation empirical model works (blue line) and how changing solely X₀ improves the fit (green line). X₀ for the green line is obtained through a fit to the data using the non-linear least-squares method. e \({X}_{0}^{{{{{{{{\rm{c}}}}}}}}}\) calculated from fully resolved simulations with Eq. (1) against the parent branch diameter prior to deformation. f \({X}_{0}^{{{{{{{{\rm{c}}}}}}}}}\) calculated from fully resolved simulations with Eq. (1) against the parent branch haematocrit prior to deformation. g Predicted \({X}_{0}^{{{{{{{{\rm{c}}}}}}}}}\) from Eq. (4) against actual \({X}_{0}^{{{{{{{{\rm{c}}}}}}}}}\) as calculated from fully resolved simulations. h Predicted haematocrit (using updated \({X}_{0}^{{{{{{{{\rm{c}}}}}}}}}\) in blue and original X₀ in orange) against the fully resolved haematocrit. The diagonal line in g and h is a visual aid to see how close the predicted values are to the values obtained from fully resolved simulations.