Particle flow pattern for silos with single opening

The silo flow problem is important to geotechnical engineers, chemical engineers and mining engineers. The classical Janssen equation (1895) which neglects the end effect has been used for design by many engineers, and this equation has also been specified in the design codes in Germany, Australia, US and UK. The Janssen theory (1895) assumes that the sand grain moves down uniformly so that there is an even movement of sand which can be described by a simple differential equation. The vertical and lateral stresses adjacent to the wall by the Janssen equation (1895) will deviate from a linear distribution, and the lateral pressure will gradually become constant with depth which has been found to agree well qualitatively with the observations. However, the equation has a major limitation in assuming the flow to be uniform which is well known to be not correct, as a flowing cone will be formed during the drawing of the material. In the present study, it is demonstrated that for silos with a single opening, a columniform funnel flow which deviates from the basic assumption by Janssen will be obtained and compared. Many interesting results from the present study of different silo cases including the arching of distribution zone, normal and shear stress distribution will be discussed.