# Tag Info

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Assuming that drag is the only force (this is not accurate - see friction). Then if you solve the differential equation: $$m \ddot{x} = -\frac{1}{2}C_d\cdot A\cdot \rho\cdot (\dot{x})^2$$ with $x(t=0)=0, \dot{x}(t=0) = v_0 [m/s]$ then the solution is : \$x(t) = - \frac{m \log{\left(\frac{m}{v_0} \right)}}{A C_d \rho} + \frac{m \log{\left(A C_d \rho t + \...

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"Euler’s equation expresses the relationship between the velocity and the pressure fields in inviscid flow. Written in terms of streamline coordinates, this equation gives information about not only about the pressure-velocity relationship along a streamline (Bernoulli’s equation), but also about how these quantities are related as one moves in the ...

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Gravity-flap valves should work as monodirectional pressure stabilisers.

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There must be pressure ( water level) difference to provide force to push water through the system. If you stop input and output for a few minutes the levels will even out , except where a baffle may prevent it .With no flow ,no pressure differential is need to move water . It is not much pressure , height of 4 " equals about 0.17 psi. Unrelated , have ...

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The pressure drop between the left and right sumps can be calculated by measurement. For fresh water 10 m = 1 bar (approx.) so 10 mm = 1 mbar (or just work in mm). There are a several useful calculators online. Figure 1. Resuts from Copely's flow rate calculator. Click for 100% magnification.) I've guessed that the pipe length is about 300 mm and that while ...

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To reiterate my edit and close the question: Looking at the link suggested and a few textbooks, I found Modern Compressible Flow: with Historical Perspective by John D. Anderson explained conical flow very clearly. To summarise, the ODE to solve is the following: Finding the solution of the flow involves being given either the cone angle and surface Mach ...

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Without storing the soda in bags, I think you will struggle to find a solution that works better or even at a lower cost than the syrup & carbonated commercial solution. Mechanical check valves are not going to work well enough at the very low pressures we'll find here. and solenoids just complicate a system that I assume you are trying to keep simple ...

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No, because the relative directions of forces and travel are wrong Consider your diagram. In order to change the frame of reference, the current would have to be pushing the boat left to right, in the opposite direction to the arrows above the green dots. The result of this would be an "apparent wind" creating the force in the direction shown. ...

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There was a wonderful article in the American Institute of Aeronautics and Astronautics (AIAA) journal (80s? maybe 70s?) envisioning a sailboat that was nothing but an airfoil (the sail) connected to a water foil (the keel). Based on the density ratio, the airfoil should be 80 times larger (IIRC) than the water foil. It then imagined people who live on ...

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Shame on the physics SE for closing it. No tacking required, although it is optional. The vessel is going directly down wind, not up wind. There is a factor called the speed ratio (SR), which is the boat speed divided by the true wind speed (TWS). TWS is the scalar difference between the wind velocity and water water velocity. And there is the associated ...

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Probably yes. To a sailboat, there's no difference between floating in a river surrounded by stagnant air, and floating in stagnant water surrounded by moving air (wind). The boat will "feel" a relative wind in both cases. The only question is whether or not a sailboat could sail upstream faster than the water is flowing downstream. The relevant ...

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River water flow creates hydrodynamic pressure which is equal to $$P_{hydrodynamic}=1/2 \rho v^2$$ If we can tap this pressure to do work it is possible to use it to move the boat upstream. One practical solution would be to have a paddle wheel like those used on riverboats turn a winch winding a cable that is anchored to the shore upstream at the desired ...

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I know this question was asked over a year ago, but this popped into my feed and I wanted to put my two cents in since this seems very interesting. I would consider analyzing the stigmas as an array (not neglecting the other stigmas), similar to how heat transfer in pin/fin arrays are analyzed. You will probably need to make some assumptions as to the ...

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There are several possibilities: A longer outlet tube to allow the velocity profile to develop but there will always be a profile The output may have a rotational component, which you could reduce by using a flow straightener - think of a "block" of drinking straws end on. To check what your profile is you could use a pitot tube and move it across ...

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Add air or C02, using a pump,to keep the contents above atmospheric pressure or at the pressure of the soda bottle. Not sure what that is as I have never measured it, but some seem to be significant and they can push out quite a bit of the contents. That means you will need two barbs to the lid. Consider making special lids - perhaps out of brass or ...

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If you examine a derivation of the Euler work equation (http://web.mit.edu/16.unified/www/SPRING/propulsion/notes/node91.html), you will see that the change in angular momentum of the fluid is proportional to the change in enthalpy of the fluid. Remember the definition of enthalpy is the flow work and the internal energy. Therefore, the enthalpy contains the ...

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