# Tag Info

## Hot answers tagged fluid-mechanics

4 votes
Accepted

### Glide Ratio of an unpowered "sub"

If all things were somehow magically equal, density does not affect things because although density increases drag it also increases lift by the same proportion. So the glide ratio doesn't change. But ...
• 3,095
3 votes

### converting air flow rate between l/min to kg/s

Given the density of air at 15 Deg C is 1.225kg/m^3, then assuming 10 litres/min is 0.1666667 litres per second as there are 60 seconds in 1 minute. 1000 litres is 1.225 kg/m^3 so 1.225/1000*0.1666667 ...
• 13.6k
3 votes

### How to determine time taken for tyre to deflate using CFD analysis?

I don't think CFD is the right tool. You can use an orifice equation, say from ASME, to calculate flow rate from inner and outer pressure. This takes the form of: \dot{m}=\frac{EC_D}{\sqrt{1-\beta^4}...
• 441
2 votes
Accepted

### What aerodynamic equation should be used to determine the drop in air pressure over an airfoil embedded within a vertical pipe?

The equation you quote isn't a physical law, it's a definition of $C_{\textrm{d}}$. You will need it, but for finding the value of $C_{\textrm{d}}$, there's no substitute for doing a scale model ...
2 votes
Accepted

### What are pressures, air-flow rates and ground clearance of some real-life hovercraft?

Although I cannot assist you with explicit formulas myself, I would like to make you aware of the book Theory and Design of Air Cushion Craft by Liang Yun, Alan Bliault, which is available (with ...
• 146
1 vote

### converting air flow rate between l/min to kg/s

Density is a function of both temperature and pressure. You can use the ideal gas law to calculate the density of air: $\rho=\frac{P}{RT}$ where $T$ is temperature, $P$ is pressure, and \$R=287 \frac{J}...
• 2,989

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