Solution (source code)

= Solution

Differentiate the equation for $f$ with respect to $x$, commuting mixed <partial derivatives> for a sufficiently smooth solution. With $y=f_x$ this gives
$$
f_{xt}+f_xf_{xx}=kf_{xxx},\qquad\boxed{y_t+yy_x=ky_{xx}.}
$$
This is the <viscous Burgers equation> when $k>0$.