BIO325H5 Lecture Notes - Lecture 5: Propulsor, Reynolds Number, Swim Bladder
Document Summary
Reynolds number: a dimensionless index that tells you whether fluid flow is laminar or turbulent. If reis <10, flow is laminar; any re >100 indicates turbulent flow. Laminar flow occurs where re is low and so viscous forces dominate; turbulent flow is where. Modified slightly from nasa"s online account: as an animal moves through a fluid the molecules of the fluid near the animal"s body surface are disturbed and so move around the animal generating forces. The forces generated depend in a complex way on the viscosity of the fluid: some of the molecules stick to the animal"s integument creating a layer near the surface called a boundary layer*. In effect the boundary layer changes the shape of the animal"s body. The flow of air or water reacts to the edge of the boundary layer as if it was the physical surface of the animal.
