Role of Valve Spacing and Vessel Contraction Wavelength on Lymphatic Pumping Performance*

The lymphatic system plays an important role in body's homeostasis through transport of lymph, fatty acid, and immune cells within an extensive network of lymphatic valves and vessels. These system of valves and vessels allow unidirectional pumping overall without any centralized pump against adverse pressure gradient, but many aspects of lymphatic  operation, especially the role of lymphatic valves, are less understood. Our work aims to explore some of these areas through fully coupled 3D fluid-structure interaction computational model to understand the effect of lymphatic valve spacing and vessel contraction wavelength on pumping performance. Our results suggest that flow rate and pumping efficiency can have a drastic difference depending on whether the valve spacing matches with vessel contraction wavelength while increased valve density from smaller valve spacing cause increase in work done by the vessel to account for increased viscous loss. Overall, our work investigates many unexplored regions of lymphatic operation and brings a greater understanding in the role that lymphatic valves play in overall pumping performance.