Both

We will now restrict ourselves to flows that are both irrotational and incompressible.

In terms of the velocity potential, by the simple existence of , irrotationality is automatic. But incompressibility requires:

Exercise:

Give a few examples of incompressible potential flows.

We will restrict ourselves even further to 2D flows, so that the incompressible 2D streamfunction exists. In terms of ,incompressibility is satisfied automatically. But irrotationality,

requires:

Exercise:

For ideal stagnation point flow (u,v)= a(x,-y),

• Is ?
• Is ?

The boundary conditions for and will be different. For flow around steady bodies, the body is a streamline, so that is constant on the body (Dirichlet boundary condition). Also the velocity normal to the body surface will be zero, so that (Neumann boundary condition.)

02/25/00 0:04:59 02/28/00 0:01:06 03/13/00 0:00:57