Effects of the Non-Newtonian Viscosity of Milk Flow in the Breast Ductal System

Numerical simulation of human milk flow inside the breast ductal system is carried out to investigate the impact of milk flow properties, specifically viscosity, on the flow regime. The geometry of the ductal system is assumed as a rigid body with six bifurcation levels. The vacuum pressure, obtained from clinical investigations, is applied as boundary conditions for numerical analysis. The simulations are performed by considering both Newtonian and Non-Newtonian milk flow properties. The streamlines of velocity fluid, wall shear stress, and milk flow expression for these two models are discussed. The results show that the non-Newtonian fluid has a higher magnitude of velocity compared to the Newtonian fluid, which leads to a greater amount of milk expression.

Aortic Valve Sinus Vorticity Dynamics and the Potential Role of Coronary Flow

Calcific aortic valve disease affects a wide range of the population in the United States. Each year there are approximately 50,000 valve replacements due to this disease [(Freeman & Otto, 2005)]. While it is unclear what the exact causes of CAVD are, it does appear to be correlated to local hemodynamic conditions particularly related to the complex spatio-temporal nature of fluid wall shear stress dynamics that the aortic side of the leaflets experience.

On the Effects of a Flexible Structure on Boundary Layer Stability and Transition

Delaying the onset of boundary layer transition has become a major research area in the last few years. This delay can be achieved by either active or passive control techniques. In the present paper, the effects of flexible or compliant structures on boundary layer stability and transition is studied. The Orr-Sommerfeld equation coupled to a beam equation representing the flexible structure is solved for a Blasius type boundary layer. A parametric study consisting of the beam thickness and material properties is carried out. In addition, the effect of fluid wall shear stress on boundary layer stability is analyzed. It is found that high density and high Young modulus materials behave like rigid structures and therefore do not alter the stability characteristic of the boundary layer. Whereas low density and low Young modulus materials are found to stabilize the boundary layer. High values of fluid wall shear stress are found to destabilize the boundary layer. Our results are in good agreement with those published in the literature.