2. Overview, Regular And Irregular Waves

Question 1

The value of the natural period depends on the

Answer 1

Restoring and mass contribution

Question 2

The amplitude of the motions at resonance deoends on the

Answer 2

Damping mechanisms

Question 3

Considering the classification of wave forces diagram.

Which loads are important for lambda/D < 5 ?

Answer 3

Diffraction loads are important

Question 4

Basic assumptions of potential flow theory

Answer 4

Inviscid: zero viscosity, ie., viscous stresses are 0

Irrotational

Incompressible: locally the fluid volum does not change. Net flux is 0

Question 5

The wavefront propagates along the positive x-axis with a speed c, expressed by

Answer 5

c = omega/k

Question 6

Wave energy E travels with a speed cg (group velocity) expressed by

Answer 6

cg = 1/2 * omega/k

Question 7

Governing equations

Answer 7

1) conservation of fluid mass

2) conservation of fluid momentum

Question 8

Stokes drift says that

Answer 8

A fluid particle has a non-zero average horizontal velocity over one period in the wave-propagating direction

Question 9

The wave power is ___ multiplied with what

Answer 9

Wave-energy density multiplied with wave-energy speed (cg)

Question 10

Long-crested means

Answer 10

The wave energy propogates in one direction, i.e., 2D waves

Question 11

Irregular waves means

Answer 11

Waves with energy distributed within a certain range of frequencies

Question 12

Superposition principle for irregular waves

Answer 12

Split the energy in the spectrum in a finite number of regular wave conponents

Question 13

We can study the response of a marine structure to irregular waves as the ___ of the responses to regular waves

Answer 13

Sum

Question 14

The 6 degrees of freedom

Answer 14

1. Surge
2. Sway
3. Heave
4. Roll
5. Pitch
6. Yaw