Tag Info

3

The truck will have in its wake some unknown mass of air almost moving with a speed $v$ comparable to the truck's speed $\bf V$. The pressure behind the truck will be lower than the pressure at the sidewalk because air pressure follows the Bernoulli equation, $$P_\mathbf{P} = P_\text{road} + \frac{1}{2}\rho v^2,$$ where $\rho \approx 1~$kg/m$^3$ is the ...

0

You seem to be looking for boundary layer separation, which occurs for sufficiently large Reynolds number. See Batchelor's Introduction to fluid dynamics, sections 5.8 to 5.10. See also: http://en.wikipedia.org/wiki/Flow_separation http://en.wikipedia.org/wiki/Boundary_layer

1

At low Renyolds number, the vortex shedding described in the question does not occur, based upon the following simulation videos: http://www.youtube.com/watch?v=ElmTA0t3bEc http://www.youtube.com/watch?v=8o-JC3R9YBY http://www.youtube.com/watch?v=sN9LP5dNWhc However, for higher Renyolds number see Nakamura et al. "Experiments on vortex shedding from flat ...

1

I recommend Turbulence: The Legacy of A. N. Kolmogorov by Uriel Frisch. It explains how turbulence is a top-down behavior, large scale turbulence in turn causes turbulence at smaller and smaller scales. This continues until a small enough scale is reached where the energy from the turbulence serves to create more heat on the molecular level. Because of this ...

1

It's largely a matter of definition. Here are some quotes. From Springer Reference: Definition There is no universally recognized definition of chaotic flows. Flows with properties that are neither constant in time nor presenting any regular periodicity are normally referred as chaotic. Fluid turbulence is generally found to be chaotic. It is ...

3

I think the simplest answer to this question would be that the stream of water has a number of forces acting on it (gravity, air drag) from many directions. Some torque is bound to be produced as the stream falls through the air. If you throw a ball or any small object from a height, it rotates, no matter how you drop it. Same logic applies here. As far as ...

Top 50 recent answers are included