Venous Thromboembolism (VTE) is a major public health problem in Western countries. In EU countries, 465,000 DVT cases and 370,000 deaths related to VTE are registered each year during immobilization and hospital bed-rest \cite{cohen2007}. A better understanding of the reasons why bed-rest favors DVT is key towards a better management of the patients and reduction of the in-hospital complications. The assessment of the hemodynamics in a 3D deep vein valve can be done thanks to numerical simulation with a Fluid-Structure Interaction (FSI) method. The FSI method used in this work is a boundary-fitted approach, meaning that the fluid and the structure are solved seperately on two distinct meshes consistent on the interface \cite{fabbri2022b}. Fluid mechanics is solved using the incompressible Navier-Stokes equations in the ALE formalism while structural dynamics of the valve is resolved based on continuum mechanics assumptions. To ensure dynamic equilibrium of the system, coupling conditions are solved with strongly coupled FSI framework. A 3D model of the valve in the closed position is first created from medical data \cite{hofferberth2020}. In this model, only the leaflet dynamics is computed from structural dynamics, while the vein itself is considered rigid as a first approximation. On the inlet, the flowrate is imposed from medical data as well. Should the abstract be accepted, an assessment of hemodynamic, wall shear stress, pressure gradient through the valve and leaflet movement analysis will be provided.