The global entropy generation rate in the zero-mean oscillatory flow of a Maxwell fluid in a pipe is analyzed with the aim of determining its behavior at resonant flow conditions. This quantity is calculated explicitly using the analytic expression for the velocity field and assuming isothermal conditions. The global entropy generation rate shows well-defined peaks at the resonant frequencies w...

Laboratory experiments were conducted to study solute transport along preferential flow paths in unsaturated, inclined fractures. Qualitative aspects of solute transport were identified in a miscible dye tracer experiment conducted in a transparent replica of a natural granite fracture. Additional experiments were conducted to measure the breakthrough curves of a conservative tracer introduced ...

The feasibility of assessing mitral flow by means of ultrasonic monitoring of backscattered power from an echo-contrast agent in the left atrium and left ventricle was studied. A mechanical model of the left heart was built in which two thin rubber balloons connected to each other in a feedback loop via two artificial heart valves mimicked the left atrium and left ventricle. The model was drive...

Objective: to investigate the efficiency of a device that generates pulsatile flow during constant-speed axial-flow pump operation for use in left ventricular assist devices. Materials and methods. The flow-generating device, hereinafter referred as «pulsator», consists variable hydraulic resistance made form hull. A tube elastic biocompatible material featuring an inner diameter 11 mm is insta...