BIO325H5 Lecture Notes - Lecture 10: Fish Locomotion, Turbulence, Reynolds Number
Document Summary
Forces on swimming- drag or lift: fins in swimming by fish, aquatic insects, reynolds numbers: creole wrasse: drag vs. lift-based labriform swimming, blackfly viscous entrainment. Defining inertia & viscosity- introduction to reynolds numbers. Swimming involves the transfer of momentum [mass x velocity] from the fish to the surrounding water . Fin gives backward momentum to the water & this action gives a forward-momentum reaction to the fish as thrust. Main momentum transfer mechanism involve 3 forces. Term roll, pitch & yaw describe body attitude change relative to gravity. Swimming involves transfers of momentum from the fish to the water & back from the water to the fish. Swimming drag (drag= resistance) on fish can be partitioned into 3 kinds: skin (friction, viscous) drag, form drag, vortex (induced) drag. Free stream" flow, where the drag effects of the passing fish cease: skin drag changes the swimming speed & the area of the no-slip.
