Mesoscale Simulations of Blood Coagulation in Flow and Quiescent Domains Using SDPD.

Blood coagulation is governed by tightly regulated reaction networks whose activation and early evolution are influenced by transport processes. While reduced kinetic models of the intrinsic and extrinsic pathways have been validated in well-mixed experimental settings, their behavior in spatially resolved domains remains insufficiently characterized. In this work, two established reduced coagulation networks are embedded within a thermodynamically consistent mesoscale particle-based framework that resolves fluid momentum transport together with multispecies advection-diffusion-reaction dynamics. Unlike conventional continuum coagulation solvers, the proposed formulation captures coupled transport and biochemical interactions through interacting particles within a unified hydrodynamic description. The framework is used to investigate the initiation phase of coagulation under controlled microvascular-like flow conditions in simplified channel geometries. The simulations reproduce characteristic thrombin generation curves (TGCs) across physiologically relevant parameter ranges while additionally revealing spatial transport effects that are not captured by outlet-averaged measures alone. In particular, the results show that transport-reaction coupling induces pronounced spatial heterogeneities in thrombin concentration, with transitions between localized activation, wall-aligned accumulation, and advective washout depending on Reynolds and Péclet regimes. Injury geometry is further shown to modulate coagulation amplification, with capped configurations producing enhanced thrombin accumulation due to localized surface-mediated activation. Complementary quiescent-domain simulations additionally reproduce qualitative trends observed in thrombodynamics assays, including fibrinogen-dependent variations in fibrin formation. Overall, the study introduces a unified mesoscale computational framework for analyzing how flow, transport, and biochemical kinetics jointly regulate early coagulation dynamics in spatially resolved domains.