Reputation
1,192
Next privilege 2,000 Rep.
Edit questions and answers
Badges
11 41
Newest
 Yearling
Impact
~57k people reached

21h
revised Proving that interval preserving transformations are linear
edited body
Apr
12
awarded  Yearling
Feb
26
accepted Dependance of diffusion coefficient on size?
Feb
23
comment Connecting the diffusion coefficient in 2-dimensions and 3-dimensions?
@lemon Let's say the fluid is water.
Feb
23
comment Connecting the diffusion coefficient in 2-dimensions and 3-dimensions?
@lemon I am aware of this equipartition theorem. But I am worried that the mean deviation along a single dimension, $\langle x_j (t) ^ 2 \rangle$, changes with the number of dimensions, due to a change in effective viscosity, for example. This would make your argument invalid.
Feb
23
comment Dependance of diffusion coefficient on size?
Yes, now I get it, $u$ is $\sqrt(T/M)$ (which the typical velocity in Maxwell-Boltzmann distribution, up to some constant factors).
Feb
23
comment Connecting the diffusion coefficient in 2-dimensions and 3-dimensions?
@lemon So $\langle x(t)^2 \rangle$ is proportional to $n$? I know about the equipartition theorem, but maybe other things change when going from 3-dimensions to 2-dimensions, like the effective viscosity.
Feb
23
comment Dependance of diffusion coefficient on size?
Sorry I missed your edits for the last 5 days, but please @notify me in comments. Thanks :)
Feb
23
revised Dependance of diffusion coefficient on size?
added 59 characters in body
Feb
23
asked Connecting the diffusion coefficient in 2-dimensions and 3-dimensions?
Feb
23
comment Dependance of diffusion coefficient on size?
Your $Re$ is a Reynold's number? So $u$ is not the instantaneous velocity of the sphere, it is just an estimate of the maximum magnitude of this velocity, which is a constant. If I am correct, you should maybe clarify this a bit in your answer
Feb
23
comment Dependance of diffusion coefficient on size?
So $u$ is the drift velocity? I don't understand why there is a drift velocity here. There isn't a drift velocity in 3-dimensions. Basically this is saying that the diffusion coefficient depends on the velocity of motion of the particles, i.e., it is not a constant, so Fick's law doesn't apply in 2-dimensions? I don't understand this
Feb
16
comment Dependance of diffusion coefficient on size?
What is $u$, in the last line?
Feb
16
comment Dependance of diffusion coefficient on size?
What is the paper by Oseen with the 2-dimensional drag coefficient?
Feb
14
comment Dependance of diffusion coefficient on size?
No, in your expressions $\eta_D$ increases with $a$ in 3D, but decreases with $a$ in 2D.
Feb
14
comment Dependance of diffusion coefficient on size?
hmmm, also, the diffusion coefficient decreases with $a$ in three dimensions, but increases with $a$ in three dimensions... that's weird. Are you sure?
Feb
10
asked Dependance of diffusion coefficient on size?
Jan
25
comment Why are four-legged chairs so common?
What if you take into account the error in leg lenghts? In 4-legs, one of the legs can be shorter/longer than the others.
Jan
25
comment Why are four-legged chairs so common?
Moreover, 4-legs have the problem that when one leg is a bit shorter/larger, it will be unstable
Jan
7
awarded  Nice Question