# Granular convection (particle distribution) calculation

• A
Summary:
Need to calculate the distribution of particles in granular convection condition
Hi All,

Am new here came particularly hoping for some guidance

I need to calculate theoretically, how different types of particles (shown below) distribute in a granular convection

Condition:
Large surface or open surface

Types of particles:
1) Low volume, Low density particle
2) High volume, Low density particle
3) Low volume, High density particle
4) High volume, High density particle

How to theoretically calculate particles distribution of the above shown conditions in granular convection. Please guide me.
Thanks.

Regards,
Vivek Rajan

Delta2

Delta2
Homework Helper
Gold Member
Which area of physics is this, Is it Statistical Mechanics perhaps?

Viky1147
Delta2
Homework Helper
Gold Member
Ok well, maybe @vanhees71 or @Chestermiller can help I am not very familiar with distributions of particles ...

Viky1147
vanhees71
Gold Member
I fear, here I'm not competent. Granular media are a very special and difficult topic. I'm not even aware of textbooks or papers.

Delta2 and Viky1147
Which area of physics is this, Is it Statistical Mechanics perhaps?
Am not sure of it. I am a mechanical engineer

I am working on a design, in which this granular convection plays a pivotal small role. So thought of documenting a valid theory on it. Did a lot of googling and ended up here hoping to get some guidance :)

vanhees71
Welcome to PF.
Maybe start here...
Numerical modelling of granular flows: a reality check. 2015.
C. R. K.Windows-Yule · D. R. Tunuguntla · D. J. Parker
https://www.researchgate.net/profil...a-reality-check.pdf?origin=publication_detail
This seems to be far more advance and too complex to understand. Is there any simple and yet proven way so that my case study can be proven.

4 types of particles under turbulent motion, I need to map, where this 4 particles will stand in a map/sketch/some illustration. But, to be proved theoritcally.

Delta2
Baluncore
Is there any simple and yet proven way so that my case study can be proven.
It is a very complex field so we can't guess what you are doing, or in which corner you are operating.
You must reduce the complexity by identifying your case;
1. The purpose of the process.
2. Material(s).
3. Particle size and density spectrum.
4. Size or scale of the equipment. How many tonnes in the heap, flow per hour ?
5. Boundary conditions, wall shape and material and friction.
6. Agitation or motion imparted to the material.

DrClaude, vanhees71, Delta2 and 1 other person
It is a very complex field so we can't guess what you are doing, or in which corner you are operating.
You must reduce the complexity by identifying your case;
1. The purpose of the process.
2. Material(s).
3. Particle size and density spectrum.
4. Size or scale of the equipment. How many tonnes in the heap, flow per hour ?
5. Boundary conditions, wall shape and material and friction.
6. Agitation or motion imparted to the material.

Types of particles:
1) Low volume, Low density particle
2) High volume, Low density particle
3) Low volume, High density particle
4) High volume, High density particle

These 4 particles, under no/large boundary condition, i need to know where will be the particles located in say after 1 minute of time in turbulent motion.

by assumption i can say high volume high density & low volume high density gets buried under than other 2 particles.

How to prove this theory?

Baluncore
How to prove this theory?
All particles have either a relatively low volume or a high volume.
All particles have either a relatively low density or a high density.
Stop referring to every particle in the universe and answer the six questions I asked.
You must identify the context if you want to receive help.

Viky1147 and Delta2
Delta2
Homework Helper
Gold Member
6. Agitation or motion imparted to the material
The OP states "4 types of particles under turbulent motion"". Doesn't that answer this question no.6?

All particles have either a relatively low volume or a high volume.
All particles have either a relatively low density or a high density.
Stop referring to every particle in the universe and answer the six questions I asked.
You must identify the context if you want to receive help.
Yes thats the context itself. These 4 category covers every particles. But,
Under granular convection, where does this 4 particles will be located?
(assuming any volume or density in this 4 categories)
How will we prove that in theory? (considering this parameters alone)

Baluncore
Doesn't that answer this question no.6?
What is the magnitude of the movement relative to particle size ?
What is the separation between the particles ?
What constrains the turbulence, I would expect them to spread across the face of the planet.
Are the particles suspended in air, a liquid ?
There has been no theory presented.

russ_watters and Delta2

Weight density:
RED particle 2kg/cm3
Blue particle 1kg/cm3

Volume:
A - Spherical radius - 2cm
B - Spherical radius - 2cm
C - Spherical radius - 1cm
D - Spherical radius - 1cm

amount of particles:
assume equally distributed no. of particles in terms of volume in a large confined space with no other particles.

consider the turbulent motion at maximum velocity of 60 m/s

particles are suspended in surface with no/less friction

Delta2
jim mcnamara
Mentor
This software models granular flow in a liquid medium- what it seems you want. But I still am sure that your question is missing more details and you will definitely need them for the model - like actual particle size spectra and material densities for example. Maybe @jrmichler can help.

https://www.flow3d.com/modeling-capabilities/granular-media/

Delta2
Baluncore
@Viky1147
You know it is a complex field, but you still want a simple solution, and you expect that simple solution to be true in any context. I believe that is irrational.

Maybe you should start by writing a set of PDEs for the generalised spectrum of particles that might be present in a generalised fluid. Then the boundary conditions and special cases of your situation can be ignored until you integrate the system.

It appears you want to develop an entire general theory of all particle interactions, something that will delay solution for several years. I would have preferred to minimise the situation being modelled from the start, so I could achieve a functional model this year.

I expect you will later announce an unexpected boundary condition, something you could have specified at the beginning. The entire system will then need to be reformulated. How many times can we expect that to happen over the next 5 years?

Just walk away Baluncore, you don't want to follow this no more.
Note to self: Unwatch this thread.

russ_watters and Delta2
jrmichler
Mentor
Maybe @jrmichler can help.
I really appreciate the vote of confidence, but we have an unsolvable problem here:

1) The OP has not, and is apparently unable to, describe the desired end result.
2) The OP has not described the range of boundary conditions.
3) The OP has not described the flow conditions.
4) The OP mentioned "granular convection condition". Convection is a particular type of flow. So what drives the convection?
5) And more...

This person, who wants to "calculate the distribution of particles", cannot even describe the problem they want to calculate. Post #6, by @Baluncore, seems to be a complete answer, but the OP replied six minutes later stating that it was "too complex to understand". The OP wants a simple answer to a complex problem without doing any work.

russ_watters
I think the intent of this discussion got misdirected. I didnt intent this as a complex problem.

In granular convection "large particles with low density" seems to push it way up, while high density small particles & high density high particles get buried.

Please correct me if am wrong (this is said to be the basic explanation of granular convection)

Now i want this in a calculation format. This was my intent. I dont want complex solutions for a simple problem.

Thanks,
Viky

berkeman
Mentor
Now i want this in a calculation format. This was my intent. I dont want complex solutions for a simple problem.
What simple problem? So far the feedback you have been getting is that it is not a simple problem. If it is simple, you should be able to come up with a couple equations and use an Excel spreadsheet to work it all out and generate some simple plots, no?

What would you propose as your first try at those Excel spreadsheet equations and the rows and columns of your first simulation?

What simple problem? So far the feedback you have been getting is that it is not a simple problem. If it is simple, you should be able to come up with a couple equations and use an Excel spreadsheet to work it all out and generate some simple plots, no?

What would you propose as your first try at those Excel spreadsheet equations and the rows and columns of your first simulation?
As quoted earlier, am not exposed to this field. This is a new theory i need to "understand" for my study, which plays a small pivotal role.

If i would know all the things you have said i would have solved by myself.

My question is this

As a mechanical engineer, i can say from the above pic, while shaking the above container,
Case a:
High volume Low density Blue balls tends to raise up

Case b:
High volume high density Golden balls tends to get buried

Am i right here or wrong?

Delta2
i have wasted my time here

everyone in this forum is asking questions (trying to establish themselves as genius by asking questions)

all these without even understanding the intent of the question