Wall friction in oscillating liquid columns

Rates of energy dissipation in an oscillating column of liquid in a pipe have been measured by a pressure-volume diagram technique. The measured rates are up to 150 per cent greater than prediction by laminar boundary layer theory, with the deviation increasing as the liquid viscosity is reduced from 42 to 1·0 cSt. This effect is believed due to periodic turbulence in the boundary layer. Some energy dissipation measurements were also made with a sand—water mixture. Less energy is required to suspend the sand in an oscillatory flow than would be required in a steady flow.