Editing Stream function (section)

=== Assumptions ===
The two-dimensional stream function is based on the following assumptions:
* The flow field can be described as two-dimensional plane flow, with velocity vector
:<math>
\quad \mathbf{u} = \begin{bmatrix}
u (x,y,t) \\
v (x,y,t) \\
0
\end{bmatrix}.
</math>
* The velocity satisfies the [[continuity equation]] for incompressible flow:
:<math>
\quad \nabla \cdot \mathbf{u} = 0.
</math>
* The domain has no holes, or only has holes that have no net flux inwards or outwards.

Although in principle the stream function doesn't require the use of a particular coordinate system, for convenience the description presented here uses a right-handed [[Cartesian coordinate system]] with coordinates <math>(x, y, z)</math>.