NetLogo Models Library:
3D/Sample Models

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Note: If you download the NetLogo application, every model in the Models Library is included.

WHAT IS IT?

This is a model of how sand particles interact with each other. The sand particles move according to the following rules:

1.) If the cell directly below is empty, move there. 2.) If the cell directly below is not empty, randomly move to one of the empty neighbors of the cell below.

HOW TO USE IT

GO: Starts and stops the simulation.

SETUP: Sets up the model.

SPACING: Determines how long the spout waits before releasing the next particle of sand.

THINGS TO NOTICE

Observe how sand rolls down a "mountain" of sand particles. Consider how this phenomenon is supported by the rules.

THINGS TO TRY

Observe how the spout will form a uniform pyramid of sand. Try DUMP SAND at a low density once you have a relatively large pyramid shape. How does this effect the shape of the pyramid? Does the pyramid ever return to its original shape?

Set the SPACING to 1. (You'll have to edit the slider, since the normal minimum is 2.) What happens? Is this just a limitation of the model rules, or does it have some plausible physical interpretation?

EXTENDING THE MODEL

Does this model accurately reflect how sand behaves? If not what rules could you devise to more accurately model sand's behavior? How could they be incorporated into the model?

What effect does weight have on sand particles? Should particles with lots of particles above them behave differently? If so, how would this change the rules?

Try simulating erosion with this model. How could you simulate wind? What effect would this have on the shape of the piles? How could you simulate rain? What effect would this have on the shape of the piles?

HOW TO CITE

If you mention this model or the NetLogo software in a publication, we ask that you include the citations below.

For the model itself:

• Wilensky, U. (1996). NetLogo Sand 3D model. http://ccl.northwestern.edu/netlogo/models/Sand3D. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

Please cite the NetLogo software as:

• Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

COPYRIGHT AND LICENSE

Copyright 1996 Uri Wilensky.

This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.

Commercial licenses are also available. To inquire about commercial licenses, please contact Uri Wilensky at uri@northwestern.edu.

This is a 3D version of the 2D model Sand.

This model was created as part of the projects: PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING IN CLASSROOMS and/or INTEGRATED SIMULATION AND MODELING ENVIRONMENT. The project gratefully acknowledges the support of the National Science Foundation (REPP & ROLE programs) -- grant numbers REC #9814682 and REC-0126227.

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