Energy Considerations in the Flow Enhancement of Viscoelastic Liquids

Flow enhancement effects due to different waveforms in the tube flow of rheologically complex fluids driven by a pulsating pressure gradient are investigated. It is found that the squarer the waveform the larger the enhancement. In each case the enhancement is strongly dependent on the viscosity function, but the elastic properties also play an important role. We determine that considerable energy savings may be obtained in the transport of viscoelastic liquids if an oscillatory gradient is superposed on a mean gradient. The closer the oscillation to the square wave the larger the energy savings.