A two-dimensional model of pulsating flow in the basilar artery

The flow in the basilar artery is modelled by a pulsating flow of a viscous fluid in a plane straight semi-infinite channel with rigid walls. To model the merging flow from the two vertebral arteries, the prescribed initial velocity profile exhibits two separate maximum values. Numerical results are presented for the downstream velocity, the wall shear and the time-dependent inlet length. Finally, the biomechanical implications of the results are discussed.     

Marangoni instability in a liquid layer confined between two concentric spherical surfaces under zero-gravity conditions

A liquid layer containing a single solute is bounded on the outside by a rigid spherical surface and on the inside by a concentric gas/liquid interface. The solute evaporates from the liquid to the gas phase and, if the surface tension depends on the solute concentration, surface-tension driven convective flows may arise (Marangoni instability). Assuming zero-gravity conditions and using a normal-mode approach, we study the linear stability of the time-dependent, spherically-symmetric concentration profiles in a motionless liquid. Numerical results are presented for Marangoni numbers and perturbation wave numbers in the case of neutral stability. It turns out that the system's stability properties are strongly dependent on the curvature of the interface and on the mass-transfer Biot number.     

Pulsating entry-flow in a plane channel

To obtain results for the title problem, the time-dependent Navier-Stokes equations have been solved numerically. Axial-velocity profiles at various distances from the entrance of the channel are shown for a number of points in time during one period of oscillation. Further some results for the time-dependent inlet length are presented.