Recent content by HS-experiment

I see what you mean now. If the submarine has the same density as water, water moving in the opposite direction as the hole has the same mass as the submarine. It cancels out. Even if the submarine is moving very rapidly, the entire system has no momentum. However if the submarine is denser than...

Hi JBriggs. I'm not sure if we are on the same page. I try to decompose the system into two parts, one ( submarine + water ), the other ( plume + water ). The ( submarine + water ) has net momentum only if the submarine has a density different from water. If the density is the same, the volume...

Hello again Physics Forums! I have a question about fluid dynamics. Perhaps someone here can help me out. I am trying to understand how a plume of water moving at some speed carries momentum within a body of water. For instance the ‘exhaust’ from a submarine propeller. I am having a hard time...

Hi Charles. Thanks a lot for your explanation and sorry if I placed this question in the wrong directory. My calculus course is coming back to me through a haze .. I forgot that when you are taking a derivative you need to add the fraction in front ## \frac{1}{2}d(r^2) ## to end up with the...

Hello Physics Forums, I am studying the equations related to analytical ultracentrifugation. The equation I am interested in describes centrifugation equilibrium, ie at the point in time when sedimentation is balanced with diffusion in the ultracentrifuge. Fortunately, unlike the Lamm equation...

Of course, that equation makes it very clear. t is of course equal to X/Vd. In this sense the width of the pulse after t seconds will be identical whether or not there is any drift. Due to the relation between mobility and diffusion coefficient, it is also equivalent in the space domain. I...

Yes, that is clear now. Its been a while since I last looked at this case and I forgot the core of it. :blushing: I guess what I am getting at is - how is momentum carried inside of a fluid, when its surroundings are all the same density? A plume of water traveling in the -x direction has a...

Hello Physics Forums, I have a fluid dynamics problem which appears to challenge some momentum principles. Suppose you have two submarines (like below), identical in shape, but not in mass. One of the submarines has density equal to the fluid, while the other is denser. They move at the same...

Hello Physics Forums I’m doing some numerical studies on diffusion. I began with monte carlo simulations on gas diffusion, and more recently I’ve started to dabble in carrier diffusion inside semiconductors. It looks like diffusion in semiconductors is a lot more amenable to experimental study...