Module 4 - Inviscid Flow Flashcards
What is irrotational flow?
Flow where the vorticity is zero everywhere in the flow
What is inviscid flow?
Effects of viscosity are neglected, with no friction, thermal conduction, or diffusion
What is incompressible flow?
Flow where changes in density are small and can be neglected
What is vorticity?
Twice the angular velocity of the flow, curl of the velocity field
What is a streamline?
Line where the tangent is parallel to the local velocity vector at each point
What is a path line?
Path that traces the route of a single fluid element within a flow
What is circulation?
The negative of the line integral of velocity around a closed curve
What flow is the velocity potential function defined for?
Irrotational
How do equipotential lines relate to streamlines
Normal (perpendicular)
What is a stagnation point?
Point where the velocity is zero, highest pressure (Cp=1 for incompressible flow)
What are the governing equations for potential flow? What is special about them?
Laplace Equation -> linear equation which allows superposition of basic flows
What are the basic flows in potential flow?
- Uniform flow
- Line Vortex
- Source/sink
- Doublet
What basic flows are used to create the flow over a rotating cylinder?
Uniform flow, doublet, line vortex
What basic flows are superimposed to create a fixed cylinder?
Uniform flow, doublet
What is D’Alembert’s paradox?
Paradox in inviscid flow where the drag of a cylinder is zero, as viscous effects cause drag which are ignored in potential flow
What is the Magnus effect? How is it used?
A rotating cylinder or sphere will produce a lift force, is used in rotating “sails” and curveballs in sports
What is the takeaway of the Kutta-Joukowski theorem?
Regardless of the shape of an object, circulation is required for a body to produce lift
