# Questions tagged [granulated-materials]

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### Calculating Pore Size from Permeability

I am building an experiment where one has a bed of sand on top of a porous plate. The pores allow air to be blown through the plate from the bottom but the pores must be sufficiently fine to not ...
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### Why do good materials operate in non-equilibirium conditions?

If we look at the majority of useful or industrial materials surrounding us, like metallic alloys, glasses, ceramics, or plastics, it is often the case that these materials went through really hard ...
127 views

### Computational modelling of sand pile

I'm currently working on a computational model of the way sand acts when being pushed around, say, by a bulldozer. Specifically, I'm trying to determine the dynamic equations which govern the way that ...
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1 vote
56 views

### What determines if a transgranular or intergranular fracture is more likely to occur?

As an example, why does glass tend to break by means of intergranular fracture? My analysis so far led me to believe that the tendency can be related to the intermolecular bond strength in a given ...
• 177
1 vote
111 views

### How do sand balls retain their integrity for so long?

A friend showed me how to make sand balls at the beach, like shown here on this YouTube video. We were both wondering how they managed to keep their shape way longer than any other sandcastle bits. I’...
• 111
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### Rotational energy in wheel and friction. Estimatiion of rubber loss

When an aeroplane wheel touches ground it goes from 0 rpm to say 800 rpm almost in an instant. Rotational inertia causes the wheel to glide on the asphalt and rubber is chipped off. How can I do an at ...
1 vote
53 views

### Using abrasive lapping, is it possible to make a perfectly round cylinder starting with imperfect cylinder(s)?

Centerless cylindrical lapping is a technique used to create a smooth and round cylinder through the use of microscopic abrasive compounds. My question is a chicken and egg problem, because it seems ...
• 611
72 views

### Is the Brazil Nut Effect quantitative?

The Brazil Nut Effect (a.k.a. granular convection) has a straightforward statistical mechanical interpretation as a system minimizing its free energy, at least qualitatively. What I wonder is whether ...
• 3,673
131 views

### How does the structure factor reflect the characteristics of particle distribution?

The structure factor is defined as follows: $$S(\mathbf k)=\frac{1}{N}\sum_i\sum_je^{-\mathbf k\cdot\mathbf r_{ij}\sqrt{-1}}$$ It is related to the radial distribution function by Fourier transform: ...
• 21
1 vote
42 views

### When pressing coffee, why does boiling water and coffee mixture appear to decrease after grounds are pressed to bottom?

When pressing coffee, why does total volume of boiling water and coffee appear to decrease after grounds are pressed to bottom?
91 views

### Settling effect of crumbs in food [duplicate]

What is the physical principle behind the following behavior: When left with the remainder of a bag of chips, or cookie crumbs, etc., when shaking this container, the smaller particles will settle to ...
• 1,305
355 views

### Why do random slabs stay dry in the rain? [closed]

The image below shows the slabbed area I can see from my work window Whenever it rains some of the slabs stay dry however, it is never consistent which ones. Can anyone explain why this happens to ...
71 views

### Is there a name for this phenomenon?

Imagine I have a cylindrical pipe closed on both ends with lids. I fill it with sand and compress the sand tightly. Now I hold the cylinder vertically and remove the bottom lid. The sand will counter ...
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1 vote
30 views

### How to classify archimedean solid quasicrystal made by stacking spheres

I have two sphere packing structures (i.e. 3N-coordinates of each structure). One is rhombicosidodecahedron and the other one is truncated icosahedron. They are clearly distinguished when they are ...
• 103
965 views

### Definition of granular material

I am doing a project on some properties of granular materials. I might have to face people who ask the definition of granular material. How can we define granular materials? One answer is "it is sand-...
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### Why valence electron to atom ratio affect stacking fault energy?

Wikipedia article on factors that affect the stacking-fault energy (SFE) of a material says: Another factor that has a significant effect on the SFE of a material and is very interrelated with ...
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1 vote
1k views

### Particles separation by shaking [duplicate]

In granulometry, say I have a tube with an heterogeneous mix of particles of different sizes (sand and stones, by instance). The tube is vertical in the usual gravity field and is placed in the air. ...
• 113
254 views

### Are there materials that strongly (macroscopically) vibrate under light of certain frequencies? If so why?

Picture an imperfect plane of loose particulate matter like sand or silt. Are there materials where if I shine light (not isotropically) on the plane I could get the particles to vibrate with large ...
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70 views

### Suffocation in a granular medium

I read of a recent accident in Alberta in which three girls fell into an open bed truck carrying canola seeds and suffocated. In that situation would it have been possible to keep breathing by using ...
• 4,474
5k views

### formula for the angle of repose

If we make piles of sand or of sugar, they form cones; the maximum slope of the cones depends on the material. Is there a formula which gives this slope (or the angle of the cone), given some ...
• 141
63 views

### Objects in granular medium

If a spherical object of certain radius and mass (let's say 10 ft, 3,000kg) is placed in a granular medium such as sand. How can you calculate the max depth to which the object would sink?
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