An experimental investigation on the speed of sand flow through a fixed porous bed

Abstract

Abstract In this study, we document several experiments that investigate the speed of the flow of fine sand through a fixed porous bed of packed glass beads under various conditions, including the height of the sand column (H) and porous bed (h) and the diameter of the glass beads (D) and sand grains (d). The experiments are conducted with glass beads packed at a constant density and sand at a different dry bulk density. The results show that the height of the sand does not affect the speed of the sand flow. The speed of the sand flow (v) decreases with an increase in h until h approaches a certain value. An equation $${\boldsymbol{v}}={\boldsymbol{a}}\sqrt{{\bf{g}}{\boldsymbol{D}}}{\bf{l}}{\bf{n}}(\frac{{\boldsymbol{D}}}{{\boldsymbol{kd}}})$$ v = a g D l n ( D kd ) is proposed, where a and k are the experimentally determined coefficients. Moreover, the flow of sand through a fixed porous bed could be regarded as parallel flow through multiple pipes, and therefore, the relationship between D and the number and diameter of pipes, N and D p, are discussed. Further investigations are needed for the result that the flow of sand through a porous bed or multiple parallel pipes cannot be simplified to flow through one orifice with a certain diameter.