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vavachan / brownian_motion

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correlations_wall #4

Open vavachan opened 9 years ago

vavachan commented 9 years ago

correlations

vavachan commented 9 years ago

correlations

vavachan commented 9 years ago

correlations

ronojoy commented 9 years ago

@vavachan, how much displacement in z do you get, compared to the size of the particle ? In other words, how much is <z^2> compared to a^2 ? If the particle displacement is very small, then there is hardly any change in the friction, and it is as if you have a constant friction which depends only on the local mean value of z. So, you need to be in the window where (a) the particle is close enough to the wall for the Faxen correction to be important and (b) there is sufficient displacement in z for the friction to acquire a position-dependence.

Also, please report all the time-scales we had discussed this evening.

ronojoy commented 9 years ago

@vavachan, please have a look at this plot, which shows the time scales we had discussed timescales You will, of course, not see this behaviour in the msd, since it is for a free Brownian particle.

vavachan commented 9 years ago

m=1 Z_0=1.1 a=1 delta T=.0001 omega=10 2*pi/omega=.621 eta=.1 m/(6 x pi x eta x a)=.53 (underdamped) correlation

Temperature is .5 ,Kb=.5 , so the width of gaussian is around .005. a is 1 , so its too small, But If i increase the distance from the wall to around 5 and increase the temperature to 200, the <z^2> is around 1 and so is a^2 , but corr

vavachan commented 9 years ago

https://www.biotec.tu-dresden.de/schaeffer/nanomechanics/res/pdf/SchaefferLangmuir2007.pdf

vavachan commented 9 years ago

corr