Unsteady Wave Motion topics include: Normal shock waves, reflected shock wave, finite waves, acoustics theory elements, incident and reflected expansion waves, shock tube relations and finite compression waves. Unsteady wave motion is a type of unsteady flow, which means the flow parameters are not independent of time. Unsteady flow problems can vary widely in nature, such as from ocean waves to a flood wave.  Unsteady wave motion can also refer to: Unsteady expansion waves: These are similar to moving shock waves, but instead of the piston moving into the gas, it moves away from... Show more

Unsteady Wave Motion topics include: Normal shock waves, reflected shock wave, finite waves, acoustics theory elements, incident and reflected expansion waves, shock tube relations and finite compression waves.

Unsteady wave motion is a type of unsteady flow, which means the flow parameters are not independent of time. Unsteady flow problems can vary widely in nature, such as from ocean waves to a flood wave. 

Unsteady wave motion can also refer to:
Unsteady expansion waves: These are similar to moving shock waves, but instead of the piston moving into the gas, it moves away from it.
Unsteady motion of shock wave: This is when the separated shock wave represents an unsteady motion along the streamwise direction.
Unsteady aspects of shock-wave / boundary-layer interaction: This includes the shear layer fluctuations and shock wave. 

Some unsteady wave motion research includes:
Unsteady shock wave dynamics: This research aims to improve the understanding of unsteady shock motion to the point where it can be reliably predicted and controlled.
Unsteady dynamics of a classical particle-wave entity: This research shows that a droplet bouncing on the surface of a vertically vibrating liquid bath can walk horizontally, guided by the waves it generates on each impact.

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Aerodynamics Practice Test: Unsteady Wave Motion

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25 Questions

1. Hugoniot equation is physically dependent on whether the shock wave is stationary or moving.

Don't knowFalseTrueMaybe

2. What is the slope for C_– characteristic line?

u – au + aua\(\frac {u}{a}\)

3. What is the continuity equation for a reflected shock wave?

ρ1W = ρ5upρ1W = ρ2(W – up)ρ1W = ρ5(W + up)ρ2(WR + up) = ρ5WR

4. What happens when the shock wave propagates in the opposite direction with the same magnitude as wave velocity?

Appears stationaryBecomes sonicVelocity increasesVelocity decreases

5. What is the continuity equation for a moving shock wave?

ρ1W = ρ2(W – up)ρ1W = ρ2(W + up)ρ1(W + up) = ρ2upρ1W = ρ2up

6. What is the relation between velocity of the wave and reflected shock wave?

WR < WWR = WWR > WWR × W = ∞

7. If the Mach number of the moving shock wave relative to the laboratory M_s = 1.25 then what is the Mach number of the reflected shock wave in a calorically perfect gas?

1.11021.23311.56711.4821

8. What is the temperature ratio across a moving shock wave in ambient air if the pressure ratio is 8.5?

3.824.212.371.43

9. How is total enthalpy related in a stationary shock wave?

h2 > h1Constanth2 < h1h02 < h01

10. If the Riemann variants are known, how can we compute the mass – motion velocity u?

\(\frac {J_+×J_-}{3}\) \(\frac {J_++J_-}{2}\) \(\frac {J_+×J_-}{6}\) \(\frac {J_+-J_-}{2}\)

11. If the wave velocity is 900 m/s and the density ratio across the shock wave is 0.6, then what is the value of velocity of induced mass motion behind the wave?

980 m/s180 m/s400 m/s360 m/s

12. Which of these is the compatibility equation along C₊ characteristic line?

du – \(\frac {dp}{ρa}\) = 0du + \(\frac {dp}{ρa}\) = 0\(\frac {dpu}{ρa}\) = 0\(\frac {du}{ρa}\) = 0

13. The flow properties of the moving wave depends on which property/properties?

Both direction and timeTimeDirectionTemperature

14. Shock tube is an application of steady motion of the shock waves.

Don't knowMaybeTrueFalse

15. What happens when normal shock wave propagates into laboratory facility?

Leaves a small area of vacuum ahead of itLeaves a small area of vacuum behind itInduces gas behind itInduces gas ahead of it

16. How is local velocity of sound related to the Riemann invariants?

a = \(\frac {γ – 1}{4}\)(J+ – J–)u = \(\frac {γ – 1}{4}\)(J+ J–)a = γ – 1(J+ – J–)a = \(\frac {γ – 1}{4}\)(J+ + J–)

17. Finite wave’s properties such as density, velocity are a function of distance.

TrueDon't knowMaybeFalse

18. What is a wave diagram?

Plot of wave motion between t and xDiagram of shock creation inside shock tubePlot of wave motion between x and tPlot of reflected wave motion between t and x

19. Riemann invariants are obtained by differentiating the compatibility equations for the characteristic lines.

TrueMaybeFalseDon't know

20. What is the velocity behind a reflected shock wave?

Equal to the wave velocityZeroLess than the wave velocityMore than the wave velocity

21. What is the Mach number of the reflected wave if the velocity of the reflected wave is 600 m/s, velocity of induced mass motion is 350 m/s and the speed of air is 400 m/s?

1.253.52.3753.561

22. Which of these is the governing parameters for change across shock wave when it is moving?

Velocity ratioDensityPressure ratioMach number

23. What is the Riemann invariant for C₊ characteristic line?

J+ = u + \(\frac {dp}{ρa}\) J+ = u + ∫\(\frac {dp}{ρa}\) = constantJ+ = u – ∫\(\frac {dp}{ρa}\) = constantJ+ = u – \(\frac {dp}{ρa}\)

24. What are finite waves?

Sound wavesWaves with large perturbationsWaves with small temperature fluctuationsWeak waves

25. What is the region in a finite wave called where density increases?

Linearized regionExpansion regionCompression regionPropagating region