To investigate the parameters that affect the formation of a conical pile and the angle it makes with the ground.
Granular materials are large conglomerations of discrete macroscopic particles (1). When they are dry, the forces between them are non-cohesive and repulsive. As a result, these granular substances are able to form conical piles under the influence of gravitational force, static friction and collisions (1). Above a threshold excitation level, the granular medium would come to rest almost instantly after the energy input is ceased after the energy input is ceased. This collective behaviour is a result of exceedingly large number of rapid inelastic collisions between neighbouring grains.
Gravitational forces exert macroscopic stresses on the conical pile.
· Affect friction, coefficient of friction
· Particle size
· Moisture content
Separate these research into the four dot points above
Angle of repose or the angle of the heap will depend on the particle size of the elements that makes up the heap. It can also define as the steepest angle or the angle of the dip at the sideways at which the actual particles start sliding down. This angle can be anywhere from 0 to 90 degrees. The angle of repose will depend on the particle shape and the interparticle friction as well. If the particle has more number of corners, the angle of repose will be decreased. At the same time if the particle does have elongated sides the impact of the particle shape on the angle of repose will be suppressed and this in turn will depend on the inter particle friction. As the coefficient of friction increases the angle of repose also will increase to some extent, there after the angle of repose will saturate and subsequently the angle of repose will start decrease. At the point of saturation, the rotation and the coefficient of friction will compete as the causes of motion of the particles (El shou
agy,2005).Fig-2 indicates the impact of the number of corners on the angle of repose, however the impact of the elongation interms of the suppression of the effect on angle of repose can also be seen in the figure.
Moisture content (MC) in the pulverized coal is found to influence the actual angle of repose of the coal particle granular. Geldart’s particle classification principles are found to influence the Angle of repose of the particles. Angle of repose or alternatively the flowability of the particles is found to depend on the particle size, which indicated a critical size above and below of which the angle of repose do have varying relation with the particle size factors(Wang,2010). The impact of the particle shape is well explained in the simulation studies done by Manoj Khanal et al XXXXXXXXXXThe limitations of the sphericity of the particles sizes in achieving the desired angle of repose is managed by including particles of different sizes and this in turn has resulted in higher angle of reposes. The findings are reported using the simulation studies in the report attached with. In homogeneous particulates it is observed that the presence of moisture will increase the angle of repose. For example the angle of repose in cashew nuts has increased from 32.5 to 38 degrees with the increase in the moisture content of the particles (Swami, XXXXXXXXXXThere are also evidences to prove the impact of the particle size and the container width and the height on the angle of repose formulation of the substances. As per the DEM based and experimentally validated results of Li et al(2016), it is shown that the angle of repose increased with the particle size, angle of repose decreased with the increase in the width of the container as well it is found to decrease with the increase in the height of the container. All these observations are reported based on iron ore granulated mix.
Collision, energy loss: (formation of the pile)
· Fluid behaviour only sets in above a threshold excitation level, with inelastic collisions
inging the granular medium to rest almost instantly after the energy input is stopped.
· In this case, it is the many particle dynamics that induces the infinite number of collisions. In one dimension, such a collision sequence leaves the particles ‘‘stuck’’ together in close contact with no relative motion.
· The attractive gravitational potential plays the role of a confining container, keeping the density high enough for clusters to form.
· Hauhouot-O'Hara et al.  evaluated the effect of particle size on the angle of repose of ground marigold petals and concluded that larger particles had higher angles of repose than smaller ones.
Static and rolling friction
· Angle of repose strongly depends on material properties such as sliding and rolling frictions and material density.
· The investigations of Elperin et al. and Coetzee et al. indicate that the slope angle increases with the increase of friction coefficient shea
A plot of angle of repose vs particle size would produce a linear trend line through the origin with a positive slope.
The purpose of experiment 1 is to investigate the effect of particle size on the angle of repose. It is hypothesised that as the particle size increases, the angle of repose also increases as a result of static and rolling friction.
Independent variable: particle size
Dependent variable: angle of repose
Controlled variables: mass of sugar, height of clamp, type and size of funnel
For each type of sugar, five different sugar particles were observed with a microscope; pictures were taken with a camera, and the size of each sugar particle was found using the polygon tool in Geoge
a as shown in appendix 1. Results are shown in table 1.
Table 1: Sizes of each sugar (μm^2)
Raw Cole generic
White Cole generic
Pure Icing suga
1 x caster sugar1 x flat wood board
1 x funnel
1 x Rule
1 x microscope
1 x retort stand
1 x coffee suga
1 x raw Cole generic sugar
1 x white Cole generic sugar
1 x white CSR
1 x dark
1 x pure icing sugar
1. The experiment was set up as shown in appendix 1.
2. 200g of white sugar (CSR), excluding mass of beaker, was measured on a scale.
3. Paper towel was used to cease sugar flow while it was poured into the funnel.
4. The camera was set to record.
5. The paper towel was removed quickly, which released the sugar onto the wooden surface.
6. Steps 2-5 was repeated for the other types of sugars.
7. Using Geoge
a, the height and width of the conical pile was measured using tracker as shown in appendix 2.
8. The angle of repose was calculated as shown in table 2.
9. Results were recorded on excel, and analysed.
Appendix 1: Size measurement
Appendix 2: Experimental set up