In this part the 2-D Burgers equation possesses only one nolinear term
such as
velocity is a constant. Taking
velocity as a constant simplifies the problem and the steepening of the
wave front always will be carried out in the x direction. This hypothesis
avoids obtaining a curve shock wave.

We take
to make the comparaison between the transversal convection speed and the
steepening speed of the wave front possible.