^{1}, Chih-Yu Kuo

^{2}, Yih-Chih Tai

^{3}, Shu-San Hsiau

^{1,a}and Shih-Hao Chou

^{1}

^{1}Department of Mechanical Engineering, National Central University, Taiwan 320, ROC.

^{a}sshsiau@cc.ncu.edu.tw

^{2}Research Center for Applied Sciences, Academia Sinica, Taiwan 115, ROC

^{3}Department of Hydraulic and Ocean Engineering,

National Cheng Kung University, Taiwan 701, ROC

A method for estimating the solid fraction of a steady granular flows moving down an inclined rectangular chute using velocity measurements, combined with knowledge of the mass flow rate through the cross section is shown in this paper. Four inclination angles, from 27° to 36° at 3° intervals, are tested. A linear interpolation scheme is proposed to interpolate the volume flow rate in each section of the chute. The present method is verified as a cost-effective and nonhazardous alternative for ordinary laboratories. Two distinct groups of streamwise dependence of the solid fractions are found. They are separated by the inclination angle of the chute and agreed with the internal friction angle. In the experiments using the two smaller inclination angles, the solid fraction ratios are found to be linear functions of the streamwise distance, while for the two larger inclination angles, the ratios have a nonlinear concave shape.