A constant$-$density fluid flows in the converging, two$-$dimensional channel as shown. The width perpendicular to the paper is quite large compared to the channel height. The velocity in the z direction is zero. The channel half$-$height, Y$,$ and the fluid $x$ velocity, $u,$ are given by

$Y=\frac{Y_0}{A+\frac{x}{2}}$ and $u=u_0(1+\frac{x}{l})(1-(\frac{y}{Y}{)}^2)$

where $x,y,Y$ and $l$ are in meters, $u$ is in $\frac{m}{s},u_0=1\mathrm{.}0\frac{m}{s},$ and $Y_0=1\mathrm{.}0m.$

Is this flow steady or unsteady? Is it one$-$dimensional, two$-$dimensional, or three$-$dimensional?