an instant in the evolution of plane Couette flow in a rectangular cell of size [Lx, 2, Lz]
![[movie of plane couette flow]](Images/ubigbox.png)
[x,y,z] directions are referred to as
streamwise, wall-normal and spanwise, respectively,
velocity components are denoted by
u(x,t) = [u,v,w](x,y,z,t) .