Answer:
0.55 hz
Explanation:
Given that the plane fly through the turbulent boundary layer of the atmosphere at a speed of 50 m/sec. And the velocity fluctuations in the atmosphere are of order 0.5 m/sec, the length scale of the large eddies is about 100 m.
The maximum speed attained will be
Maximum speed = 50 + 0.5 = 5.5 m/s
The Length = 100m
Speed = FL
Where F = frequency
Substitute speed and distance length into the formula
55 = 100F
F = 55/100
F = 0.55 Hz
Therefore, the highest frequency the anemometer will encounter will be 0.55 Hz
Answer:
40079 Hz
Explanation:
1. The first step is to calculate energy dissipation ∈=u^3/l and here u is fluctuating velocity
∈=(0.5^3)/100 = 0.00125 m^2/s^3
2. Find out the length scale of the small eddies
η=(viscosity/∈)^1/4
η=(1.470e-5/0.00125)^1/4 = 0.00126 m
3. The frequency associated with these small-scale eddies will be the greatest frequency the anemometer will encounter, thus:
u_max=f_max * η
u_max = u + u' = 50+0.5=50.5 m/s
f_max = u_max/η = 50.5/0.00126 = 40079 Hz
This is the heighest frequency the anemometer will encounter.
