Three-dimensional fluid-structure interaction modelling of the venous valve using immersed boundary/finite element method.

Research on venous hemodynamics is pivotal for unravelling venous diseases, including varicose veins and deep vein thrombosis, essential for clinical management, treatment and artificial valve design. In this study, a three-dimensional (3D) numerical simulation, employing the immersed boundary/finite element method, is constructed to explore the fluid-structure interaction (FSI) between intravenous blood and venous valves. A hyperelastic constitutive model is used to capture the incompressible, nonlinear mechanical response. Our findings reveal the periodic characteristics of valve movement and intravenous blood flow throughout the cardiac cycle, alongside quantified physiological parameters such as blood pressure, flow rate, geometric orifice area, and stress-strain distribution on venous valve surfaces. The study unveils a significant correlation between dynamic valve motion and vortices within the venous sinus. Stress and strain concentrate primarily at the free edge of venous valves, which is in contrast to 2D modelling. Moreover, increased hydrostatic venous pressure is found to be the key to venous vessel dilation. The effects of fibrosis and atrophy of venous valves on venous hemodynamics are compared and analysed. This FSI numerical study introduces a fully 3D framework for modelling the venous system, expected to provide crucial references for understanding the development and mechanism underlying venous diseases, thereby furnishing a scientific underpinning for their prevention, diagnosis, and treatment.