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Example of use of the solidParticlesolidParticleCloud classes

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Old   April 21, 2009, 06:50
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  #21
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Håkan Nilsson
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The dieselSpray classes have an injector implementation. Have a look there. There is no such in the very simple solidParticle class.

Also have a look at icoLagrangianFoam, which probably has it.

Håkan.
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Old   June 10, 2009, 08:52
Default simpleLagrangianFoam
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ZHOU Bin
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Hi Håkan,

Thank you for a long-way help.

As I could see there is something not correct in icoLagrangianFoam solver, I derived the particle movement, and with my steady state flow field by simpleFoam, I plan to inject particle. Now I developed my simpleLagrangianFoam solver, which could fulfill my idea.

I have 2 questions to anybody who has experience with lagrangian:

1. Do we consider the particle diameter when particle hits the wall?
This is important, and I am thinking about this problem, if you have some suggestions, welcome.

2. How to get the concentration of particle in the air?
I have an idea:
set one sampling plane upstream, to see at each second, how many particles are through, say n_up(particles/second), with the mean air velocity v_up m/s and cross section A (m^2), we know the upstream concentration (n_up/(v_up*A), particles/m^3 at each second);
The problem is whether I can do this by OF 1.5.x?

If anyone who has problem about particles, welcome for discussion.

Best regards,

Bin
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Old   June 11, 2009, 03:09
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Håkan Nilsson
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Hi Bin,

You need to implement an injector, since there is no such in the solidParticleCloud class. Have a look at dieselFoam.

Håkan.
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Old   June 11, 2009, 05:21
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ZHOU Bin
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Hi Håkan,

simpleLagrangianFoam solver is developed, which could model the particle movement in the steady-state flow field.

I will learn if in dieselFoam they consider the particle diameter when hitting the wall. If yes, I will include this in my solver.

I could see that my solver could only inject one particle at one time step, I have no idea how could I inject 2 or more particles at one time step.

Welcome comment or suggestions.

I am also practicing dieselFoam now, hoping to find something.

Bin
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Old   June 16, 2009, 02:29
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ZHOU Bin
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Hi Foamers,

The two problems are solved. Again my concern is:

How to get the concentration of particle in the air?

Method 1:
set one sampling plane upstream, to see at each second, how many particles are through, say n_up(particles/second), with the mean air velocity v_up m/s and cross section A (m^2), we know the upstream concentration (n_up/(v_up*A), particles/m^3 at each second);

Method 2:
set one "box", to see how many particles are in this "box", and calculate the concentration.

The problem is I don't know how can I set this kind of plane/box to count the particles.

Thinking...

Bin
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Old   June 17, 2009, 05:06
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ZHOU Bin
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Hello, dear Foamers,

After one day's work, I still can not find a way to define the concentration.

My purpose is to: define the efficiency of the cylinder capturing particles.

I set to generate 3 particles every time step, now let's see the log:
**************************
...
Moving Particles
2000 Particles moved. 0 walls hit. 4 particles left the model. 3 particles injected.
...
**************************
As we could see that the number of particles left the model > the number of particles injected. It seems strange, but it is so. Here I attach a pictures of my simple model, hoping some friends could give me some suggestions.

The efficiency is defined as: 1-C_out/C_in, where C_out is the downstream concentration, and C_in is the upstream concentration.

Thanks for attention.

Bin
Attached Images
File Type: jpg Particle_count_ok.jpg (102.1 KB, 60 views)
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Old   June 17, 2009, 22:04
Default Calculate DPM concentration in each cell
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ZHOU Bin
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Dear Foamers,

For my above problem, in the solver file, after we move the particles, we have already got "(x,y,z) cell" in the "positions" file.

Idea:
Can we include one file, which can calculate the particle numbers, then particle concentration at each cell from the "positions" file?

Algorithm:
1. generate a label list (1 1 1 .....1) like cell.size();
2. read the positions file, get the first cell index, sum those in the same cell, we get the particle numbers NP in this first cell, then we get the cell volume, i.e. mesh.V()[cellID], so we know the concentration NP/mesh.V()[cellID]; at the same time, give the corresponding cell label 0 instead of 1;
3. go to the second cell, if the label is 0, go the third cell; if not, do as 2;
4. until the end of positions file, we set the rest cell concentration to be 0;
5. in this way, we may sample or use areaAverage get the concentration of some plane;

I have this idea, but I am not sure if this is right or not? I have problem coding, if some one could do me a favor, really appreciate.

Bin
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Old   July 9, 2009, 03:00
Default Brownian motion of sub-micro particles
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Dear Foamers,

I have made a code for the Brownian motion of sub-micro particles, but I need someone who is willing to test it.

If who is interested in this, please add my skype or msn.

Bin
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