This paper will employ Lie's method to obtain a closed-form solution of partial differential equations (PDEs) describing flow at the stellar surfaces. The solution obtained gives explicit expressions for the flow variables ahead and behind the shock; we were also able to provide expressions for shock velocity and path. The evolution of the discontinuity wave and its interaction with the shock wave has been discussed in detail. The interaction of the waves produces two reflected waves, whereas the shock acceleration experiences a jump. Explicit expressions are obtained for the amplitude of the reflected waves and the jump in the shock acceleration.