barstool scientist ahoy!

[MoeMag]

I am trying to figure out the physics of a pile.


I am mainly curious what variables change the cross sectional angle a cone shaped pile.

I tried to find formulas regarding the subject but have thus far failed.

Someone's gotta know.

:cheers:

[TeamBob]

:wow:

[kruger]

I really dont know the formula, but I would think that the variables would be friction and gravity, and individual weight of the pieces. But, just a guess.

[Hilltop Customs]

kind of like sand dunes with their limited slope angle?

particle size variability, particle shape, friction coefficient of particle surface, particle deformation

theres probably a lot more. Moisture content, compressive loads went forming the pile.(hehe think of a cone shaped sandcastle)

[MoeMag]

kind of like sand dunes with their limited slope angle?

particle size variability, particle shape, friction coefficient of particle surface, particle deformation

theres probably a lot more. Moisture content, compressive loads went forming the pile.(hehe think of a cone shaped sandcastle)

Maybe i am over thinking the problem. I have to make a control volume, of a top filling container. kinda worried that depending upon the material i could end up with air gaps if the angle of the lid is too shallow. if jarred... those air gaps could throw off the measurement. I need the whole thing to be as short as possible.

Its one thing to test what i have to use it for... but i have no idea what ELSE could be put in it.

didnt know if there was an ideal angle or something simple out there.

45° is pretty safe i suppose.

[Pneumagger]

Already mentioned, but it's going to come down to particle size, consistency, and surface properties.
Plus, pile density is going to play a huge role in the final slope.

For example, your pile could be made of 1/4" ball bearings. Odds are it will take an angle of 60* or less. 60* is the angle of a maximum density pyramid of spheres.
However, say you had cubes (salt granules). You could theoretically stack vertically. Unlikely, but pussible. In these scenarios, friction and water content plays little role versus gravity and geometry.

Some basic relationships I'd start with include:
Gravity aids geometric interference to create steeper angles
Water wetting (on most surfaces) aids steeper angles via "hydrogen bonding" at the wetted surface interfaces.
Gravity and friction hinder the angle steepness. I'd say use dynamic friction coefficients.
You should statisticly never end up with a pyramid steeper than the maximum density pyramid.
The more particle size variation you have the less accurate a max density pyramid estimate will be.

Good luck, and when in doubt just say your going to use gladware.
It's cheap enough to throw away and tough enough for life.