Study of non-hydrostatic pressure distribution of free surface flow in a rockfill porous media

Increasing the slopes of water surface and bed or making a considerable curvature of streamlines, resulted in the vertical pressure distribution deviate from hydrostatic distribution. Because of severe energy loss and big difference between upstream and downstream water surface elevations in rockfill porous media, it is expected that pressure distribution be non-hydrostatic. In this paper, with the aid of Buckingham π theorem and regression analysis, a relationship is proposed for water surface profile in rockfill porous media. Moreover, a non-hydrostatic pressure distribution for rockfill porous media is derived by applying Euler equation including the effects of streamlines curvature and large slopes. A series of laboratory experiments have been conducted on rockfill materials with diameter of 1.68 cm and two media length of 0.5 and 1.0 m. It is found that the introduced model gives satisfactory results compare to the experimental results so that mean absolute relative error of water surface and longitudinal pressure profile between two series of the data are 1.31 and 1.71 percent, respectively.