Chapter 6: Problem 85
Imagine a garden hose with a stream of water flowing out through a nozzle. Explain why the end of the hose may be unstable when held a half meter or so from the nozzle end.
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Chapter 6: Problem 85
Imagine a garden hose with a stream of water flowing out through a nozzle. Explain why the end of the hose may be unstable when held a half meter or so from the nozzle end.
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A nozzle for an incompressible, inviscid fluid of density \(\rho=1000 \mathrm{kg} / \mathrm{m}^{3}\) consists of a converging section of pipe. At the inlet the diameter is \(D_{i}=100 \mathrm{mm},\) and at the outlet the diameter is \(D_{o}=20 \mathrm{mm} .\) The nozzle length is \(L=500 \mathrm{mm}\) and the diameter decreases linearly with distance \(x\) along the nozzle. Derive and plot the acceleration of a fluid particle, assuming uniform flow at each section, if the speed at the inlet is \(V_{i}=1 \mathrm{m} / \mathrm{s}\). Plot the pressure gradient through the nozzle, and find its maximum absolute value. If the pressure gradient must be no greater than \(5 \mathrm{MPa} / \mathrm{m}\) in absolute value, how long would the nozzle have to be?
Consider a two-dimensional fluid flow: \(u=a x+b y\) and \(v=c x+d y,\) where \(a, b, c\) and \(d\) are constant. If the flow is incompressible and irrotational, find the relationships among \(a, b, c,\) and \(d .\) Find the stream function and velocity potential function of this flow.
The \(\tan \mathrm{k},\) of diameter \(D,\) has a well-rounded nozzle with diameter \(d .\) At \(t=0,\) the water level is at height \(h_{0} .\) Develop an expression for dimensionless water height, \(h / h_{0},\) at any later time. For \(D / d=10,\) plot \(h / h_{0}\) as a function of time with \(h_{0}\) as a parameter for \(0.1 \leq h_{0} \leq 1 \mathrm{m} .\) For \(h_{0}=1 \mathrm{m},\) plot \(h / h_{0}\) as a function of time with \(D / d\) as a parameter for \(2 \leq D / d \leq 10\)
Consider the flow field with velocity given by \(\vec{V}=\left[A\left(y^{2}-x^{2}\right)-B x | \hat{i}+[2 A x y+B y] \hat{j}, A=1 \mathrm{ft}^{-1} \cdot \mathrm{s}^{-1}, B=1\right.\) \(\mathrm{ft}^{-1} \cdot \mathrm{s}^{-1} ;\) the coordinates are measured in feet. The density is \(2 \operatorname{slug} / \mathrm{ft}^{3},\) and gravity acts in the negative \(y\) direction. Calculate the acceleration of a fluid particle and the pressure gradient at point \((x, y)=(1,1)\)
Describe the pressure distribution on the exterior of a multistory building in a steady wind. Identify the locations of the maximum and minimum pressures on the outside of the building. Discuss the effect of these pressures on infiltration of outside air into the building.
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