Abstract
This thesis focuses on the study of venous valve dynamics and associated hemodynamics in the deep veins of the lower limbs. It presents the anatomy and physiology of venous valves, followed by a review of existing numerical work on venous valves. The main objective is to better understand the hemodynamics of venous valves, as well as their potential implications in diseases such as deep vein thrombosis.The research is based on the surface reserve hypothesis, which proposes that valve opening results primarily from the three-dimensional curvature of the leaflets and not from significant tissue stretching. To test this hypothesis, a geometric model of the femoral venous valve was developed. This model was used to perform a comprehensive structural analysis of the valve leaflets, studying their deformation under different mechanical loads.Numerical fluid-structure interaction (FSI) simulations were then carried out to reproduce blood flow conditions in the respiratory pump, when the patient is in the supine position. The results show that the valve's sensitivity to pressure enables it to open with low pressure loss, ensuring good venous return. However, the complex structures of blood flow, including zones of recirculation and redirection of flow downstream of the valve, reveal challenges in drainage efficiency, especially with regard to limited particle movement in the sinus base.The thesis also highlights the limitations of existing models based on opening by leaflet stretching, and proposes an alternative model based on opening by surface reserve. The work has enabled us to better characterize venous valve dynamics and explain some of the clinical observations concerning the efficiency of valve opening and closing.In conclusion, this thesis proposes a new approach to modeling venous valves, taking into account the three-dimensional geometry and actual dynamics of the leaflets. The results obtained open up prospects for improving the design of venous valve prostheses and understanding the mechanisms involved in venous pathologies, while identifying aspects requiring further study, such as the influence of flow conditions or vein geometry.