Final Review Flashcards
What is quantization error?
When an analog signal is rounded to the nearest digital value.
How do you prevent quantization error?
1) Higher bit count
2) Faster sampling rate
What do the dimples on a golf ball do?
1) Dimples induce turbulence
2) Separation points move back
3) Smaller wake
4) Friction drag increases
5) Pressure drag reduces a greater amount
What is aliasing?
Sampling frequency too low so it gives a fake frequency
How do you prevent aliasing?
1) Increase sample rate
2) Use LPF
What is the Nyquist frequency?
The largest frequency that can be measured by the sampling rate you’re using.
How do you find the Nyquist frequency?
Its half the sampling rate
What is spectral leakage?
If you window in a non-integer # of wave cycles, the computer will repeat the discontinuity. Leakage is distributed normally to the surrounding frequency.
What two criteria do you need to have separation?
1) Adverse pressure gradient
2) Viscosity
What is an adverse pressure gradient?
When P downstream is higher than P upstream
What is separation?
Boundary layer separates from object due to adverse pressure gradient
What are the two kinds of head losses in pipes?
1) Major-straight sections of pipe
2) Minor-Everything else
What is head?
relates the energy in an incompressible fluid to the height of an equivalent static column of that fluid
Why do head losses use units of length?
Energy per unit weight
Units of force cancel leaving length
What are the two types of drag?
Pressure
Friction
