Investigations of lymphatic fluid flow

The lymphatic system returns fluid to the blood stream from the tissues to maintain tissue fluid homeostasis. The collecting lymphatic vessels actively pump fluid against a body scale pressure gradient, i.e., from tissue interstitial space to the venous side of the blood circulatory system. The collecting lymphatic vessels pass the lymphatic fluid to lymph nodes that filter the lymph before it is returned to the circulatory system.This thesis presents work undertaken to create a fluid structure interaction model of a lymph node with afferent and efferent lymphatic vessels. The model is built in COMSOL Multiphysics, a commercial finite element software.Four pieces of novel work are presented in this thesis. Firstly, an optimisation method used to approximate the material properties for the collecting lymphatic vessel from the pressure diameter behaviour. Secondly, model of the collecting lymphatic valve with surrounding wall used to investigate valve closing behaviour. Thirdly, an image based model of a lymph node where the material properties are optimised to experimental data and based on selective plane illumination microscopy images. Finally, an image based model of a lymph node based on computed tomography images that shows how the structure within the node affects the fluid flow pathways.