hydrodynamics

KeelyNet: Dale Pond: The Four Basic Types of Cavitation (January 1st, 1995)

KEELYNET:CAVITY1.ASC

                                  CAVITATION

There are four basic types of cavitation. Fundamentally cavitation results
from a drop in pressure on a liquid creates pockets or bubbles in the liquid -
an increase in pressure causes these bubbles to collapse resulting in a
tremendous "local" force which can cause damage to metals, emulsification, de-
gasification, sonoluminescence and many other strange and wonderous phenomena.

Fish Exploiting Vortices Decrease Muscle Activity - forelvortex.pdf

 James C. Liao,  David N. Beal,  George V. Lauder,  Michael S. Triantafyllou

 

Fishes moving through turbulent flows or in formation are regularly exposed to vortices. Although animals living in fluid environments commonly capture energy from vortices, experimental data on the hydrodynamics and neural control of interactions between fish and vortices are lacking. We used quantitative flow visualization and electromyography to show that trout will adopt a novel mode of locomotion to slalom in between experimentally generated vortices by activating only their anterior axial muscles. Reduced muscle activity during vortex exploitation compared with the activity of fishes engaged in undulatory swimming suggests a decrease in the cost of locomotion and provides a mechanism to understand the patterns of fish distributions in schools and riverine environments.....

Part 1B Engineering: Biological and Medical Engineering, Fish Swimming, Lecture 1 -2 - Trout_propulsion.pdf

..."Evidence suggests that many fish exploit the natural instability of the flow energetics to assist them in propulsion and maneuvering. By tuning their own kinematics, the fish is able to swim efficiently, to generate large thrust and turning forces, and to move silently through the flow with minimal wasted energy...."
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