Fluid-structure interaction dynamics of cervical lymphatic vessel pumping and valvular function.

A substantial portion of cerebrospinal fluid (CSF) drains through cervical lymphatic vessels (CLVs), a pathway mediated by basal and dorsal meningeal lymphatics. Impaired drainage along this route has been implicated in ageing, Alzheimer's disease and traumatic brain injury. Despite considerable experimental investigation of CLV structure and function, computational modelling of this pathway remains limited. Here, we present a fully coupled two-dimensional fluid-structure interaction (FSI) model of a murine CLV constructed using the lattice Boltzmann method for fluid dynamics and the immersed boundary method for the vessel geometry. Distinct from previous lymphatic vessel models, this framework is parametrized using data from recent in vivo imaging studies of CLVs. Using this model, we characterize the transient FSI dynamics within a single lymphangion, the pumping performance across a chain of three lymphangions with varying contraction phase delays and the role of circular sinus geometry in regulating CSF transport under both favourable and adverse pressure gradients. Our results provide the first high-fidelity simulation of CSF drainage through CLVs, bridging a gap between experimental observations and mechanistic understanding. This work offers new insights into CLV pumping behaviour and valve function, which helps inform the design of future experiments and therapeutic strategies aimed at enhancing CSF clearance.