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Diffusion of particles

  1. Mar 1, 2010 #1
    hi all:
    i have some insects/particles that i placed in the center of an arena, and tracked their position after a set period of time. what i can get in matlab is a 2d scatter plot (several hundred x,y points). i have several different types of particles that show a larger or smaller degree of spread from the center, and have collected their endpoints (i don't have individual trajectories).

    can i do something more interesting to communicate just 'how scattered' these particles are after time t? any good tutorials on this given my data (time 1, distance 0; time 2, distance X)? i think i might not be looking for a "diffusion coefficient", since i'm looking at single particles and not concentrations.

    i think i might be looking to understand something called a "correlation time".

    Thanks for any ideas
    Last edited: Mar 1, 2010
  2. jcsd
  3. Mar 2, 2010 #2
    When you say 2d scatter plot, do you mean t, r, θ or equivalent (t, x, y)? If you are tracking insects, do you expect any "clumping" meaning natural attractors (social behavior)? Do you have several different simultaneous insect types? Like predator-prey? Measurement of many individual insects is sufficient to get a diffusion coefficient. Sometimes the diffusion coefficient depends on insect concentration (density), like locusts. Locusts begin swarming when a critical density is reached. See


    Bob S
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