# Tag Info

1

Yes, the fluid particles are fighting against the higher static pressure and use their kinetic energy to overcome this. It is like in a pendulum. (In your first phrase everything is on contrary, unfortunately.)

-1

Take an A4 sheet of paper. Hold it by both corners on the short end, with the edge horizontally facing you and the long end hanging down, away from you. Now hold it close to your mouth and blow ONLY OVER the paper. You are not causing any airflow under the paper, just above it. Still the paper will rise as you blow over it. What is lifting it, is the air ...

1

For volumes of air of different temperatures separated by a vertical opening such as a doorway, the physics is different to that of convective flow over a heated surface. If we have two volumes of air at different temperatures separated by a vertical opening, the interface in the plane of the opening is not stable and a flow will result. The flow is driven ...

3

I have experienced rather similar effects on several shower systems. The problem typically occurs when the mixer is working below its intended pressure or flow range. My experience is that high water pressures and flow rates are less problematic than gentle flow. Where I have fitted a shower pump, the problem has gone away. I once tried a "turbo" ...

1

Surfactants can be added to change the surface tension (even in the ppm region). Polymers as well can affect the viscosity and there is a phenomenon known as polymer surfactant interaction that decreases the concentration required to achieve similar changes in viscosity. Typically both surfactants and polymers decrease the shear viscosity while increasing ...

1

regarding surface tension: Surface tension of water is easily reduced by adding chemicals called surfactants to it. The quantity of surfactant required to get a big change in surface tension is so small that it will not affect the viscosity. Surfactants are the active ingredients in dishwashing detergent liquid, which is the classic method of reducing ...

1

As I recall, surface tension can be changed by an additive, such as a detergent. Viscosity probably requires dilution with another liquid.

2

Such a shield falls into the "better than nothing" category. It stops you from exhaling directly towards other people, but doesn't stop your aerosols from mixing into the atmosphere. It takes very little time for particles to distribute over long distances (think bacon smell from the kitchen reaching upstairs). The reason to use a mouth&nose ...

0

Bernoulli's principle should give you $p=\rho v^2/2$, where $\rho$ is the water density. I'm just not sure about the range of applicability since it is derived for incompressible liquid (where water is just fine) and steady flow. The latter might depend, for instance, on the shape of the hose output. Anyway, this is probably a decent approximation.

1

How do I choose between using the enthalpy via $q=m'(h_2-h_1)$ and specific heat via $q=m'{C_p}(T_2-T_1)$ to analyze this flow. They are pretty much the same. At constant pressure $$h_{2}-h_{1}=c_{p}(T_{2}-T_{1})$$ But if the heat exchanger is a steam condenser or evaporator it is more convenient to calculate $\dot q$ using the enthalpies of the heat ...

0

The open system (control volume) version of the first law of thermodynamics applied to this problem tells us that the rate of heat addition to a stream passing through the heat exchanger is equal to the mass flow rate times the change in specific enthalpy of the stream. For a fluid at constant pressure, the specific enthalpy change is $\Delta h=C_p\Delta T$ ...

1

At 3 meters of depth water pressure would be about 4.41 psi. If your water supply is greater than 4.41 psi then water will come out.

2

Yes. The pressure of your domestic water supply line is plenty enough to push water up 11 feet. I water the potted plants on my second-story deck in exactly this way and it works fine. I use ordinary 3/4" garden hose with a woven nylon braid inside. The rule of thumb is this: 15 PSI will push water up about 33 feet, 30 PSI gives you 66 feet and 45 PSI ...

0

The moving object creates a higher pressure in front of it as it pushes the fluid off to the sides, as well as the lower pressure behind it. Streamlining will help to lower the fluid resistance. But it always takes some energy to cause movement of the fluid.

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