Neglecting brownian motion for certain particle diameters?

AI Thread Summary
Brownian motion can be neglected for larger particles in fluid flow, particularly for ships, but remains significant for small molecules. The criteria for neglecting Brownian forces depend on the specific time and length scales involved, as well as the desired precision of the analysis. As particle diameter increases, the influence of Brownian motion diminishes. Understanding these parameters is crucial for accurate modeling in fluid dynamics. Ultimately, the decision to neglect Brownian effects should be based on the context of the particles being studied.
sina_mech
Messages
12
Reaction score
0
Hi,
Imagine we have few particles with different diameters in fluid flow. so, can we neglect brownian forces at certain particle diameters?
Actually I'm looking for a criteria in which we can neglect the effect of brownian forces in fluid flow.

Thanks :-)
 
Physics news on Phys.org
Sure. You can certainly neglect it for ships, but not for small molecules. The size where you can start neglecting it depends on the other time and length scales and the precision you are interested in.
 

Thread '1:1 versus 2:1 Mechanical Advantage debate'

The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
View full post »

Thread 'Newton's first law?'

Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
View full post »

Thread 'Free fall of person in a sled to direct horizontal motion by atmospheric resistance'

Let there be a person in a not yet optimally designed sled at h meters in height. Let this sled free fall but user can steer by tilting their body weight in the sled or by optimal sled shape design point it in some horizontal direction where it is wanted to go - in any horizontal direction but once picked fixed. How to calculate horizontal distance d achievable as function of height h. Thus what is f(h) = d. Put another way, imagine a helicopter rises to a height h, but then shuts off all...
View full post »

Similar threads

Equation for Brownian Motion Trajectory
Replies
4
Views
2K
I Brownian motion of charged particles?
Replies
8
Views
2K
Q: Fokker-Planck (Brownian motion) for undergrads?
Replies
4
Views
1K
I Is Brownian motion a purely classical phenomenon or is it also quantm?
Replies
2
Views
1K
I Brownian motion and continuity
Replies
23
Views
2K
A Effects of a spatially nonuniform diffusion parameter
Replies
6
Views
2K
I Brownian motion and the resultant of forces
Replies
22
Views
3K
Flow of air through an open tube with a balloon
Replies
9
Views
3K
I Please help me understand the double slit experiment and conclusion
2
Replies
65
Views
3K
Does Fluid Dynamics Explain Pressure Gradients in a Frictionless Tube?
Replies
48
Views
5K

Hot Threads

Recent Insights

Back
Top