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Using Boundary Conditions: Screencasts

Simplifies the Navier-Stokes equation for flow between two parallel plates and sets up boundary conditions for different situations for parallel plates.

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Describes how to solve for the velocity profile for laminar flow through a pipe using the Navier-Stokes equation.

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Important Terms:

No slip boundary condition: The velocity of the fluid at the interface between the fluid and a solid surface will be equal to the velocity of the solid surface.  This velocity can be zero or non-zero.

Symmetrical boundary conditionThe shear stress on a fluid at a point or line of symmetry is zero.  An example of this would be at the center (r = 0) of a fluid flowing through a pipe.

Stress continuity boundary condition: The shear stress at the interface between two fluids must be the same for both fluids.  If one of the fluids is inviscid (such as air), then the shear stress at the interface must be zero for both fluids.

Velocity continuity boundary condition: At the interface between two fluids, the velocities of the fluids must be equal and continuous.