Proceedings of the 2 nd International Conference on Fluid Flow, Heat and Mass Transfer Ottawa, Ontario, Canada, April 30 – May 1, 2015 Paper No. 163 163-1 Pulse Wave Velocity Prediction in Multi-Layer Thick Wall Arterial Segments Jeffrey S. Lillie, Alexander S. Liberson, David A. Borkholder Rochester Institute of Technology, Rochester, NY, USA Abstract- Pulse wave velocity (PWV) is an important index of arterial hemodynamics, which lays the foundation for continuous, noninvasive blood pressure automated monitoring. The goal of this paper is to re-examine the accuracy of PWV prediction based on a traditional homogeneous structural model for thin-walled arterial segments. In reality arteries are described as composite heterogeneous hyperelastic structures, where the thickness dimension cannot be considered small compared to the cross section size. In this paper we present a hemodynamic fluid - structure interaction model accounting for the 3D material description of multilayer arterial segments based on its histological information. The model is suitable to account for the highly nonlinear orthotropic material undergoing finite deformation for each layer. An essential ingredient is the notable dependence of results on nonlinear aspects of the model: convective fluid phenomena, hyperelastic constitutive relation for each layer, and finite deformation. The dependence of PWV on pressure for three vessels of different thicknesses is compared against a simplified thin wall model of a membrane shell interacting with an incompressible fluid. Results show an asymptotic accuracy of an order of h/r 0 is predicted. This work help lays the foundation for continuous, noninvasive blood pressure automated monitoring based on PWV. Keywords: Pulse wave velocity, modeling, noninvasive blood pressure, convective fluid phenomena, hyperelastic, finite deformation Nomenclature A Cross sectional area (m 2 ) u Axial flow velocity (m/s) p Transmural pressure (Pa) ρ Density of incompressible fluid (kg/m 3 ) f Friction term (m/s 2 ) 0 0 , r r i Internal wall and mid-wall radii in a zero stress condition respectively (m) η Ratio of the wall deflection to r 0 x r     , , Stretch ratios in a radial, circumferential and axial directions respectively   , x  Circumferential and axial Cauchy stress components (Pa)  E , r E Circumferential and axial Green-Lagrange strain components A       22 12 12 11 A A A A Symmetric tensor of material constants Subscripts (t,x) Derivatives by time and axial coordinates Superscripts T Transposition 1. Introduction The potential of estimating arterial blood pressure based on PWV has been investigated based on statistical regression models, or empirical representation of an incremental isotropic elastic modulus as a function of a transmural pressure [1,2]. Relating physically based characterizations verified in vitro [3,4] and in vivo, have been created by modeling arteries as fluid-filled compliant thin walled cylindrical membrane shells. The present paper describes a mathematical model predicting PWV propagation with