Lecture 12 - Aquatic animal propulsion

Question 1

Three theories of fish swimming?

Answer 1

A resistive force theory - The main force of interaction between the animal
and the surrounding fluid is considered to be
the resistance caused by the viscosity of the fluid.

A reactive force theory - The force of interaction between the animal and the surrounding fluid is separated into two parts: tangential force (resistive), and
normal force (reactive) generated by the inertia of the fluid.

A two-dimensional section theory - Similar to the wing’s 2D theory, considers the vortex wake due to the oscillatory motion of the tail.

Question 2

Characteristics of Anguilliform and carangiform swimming?

Answer 2

Anguilliform - Re < 1
Carangiform - Re > 1

Question 3

Undulatory vs oscillatory movement?

Answer 3

Undulatory - Motion involve the passage of a wave along the propulsive structure.

Oscillatory - The propulsive structure swivels on its base without exhibiting a wave
formation.