In this paper, we study the interaction of 2D vorticity waves with a normal shock which is an elementary problem in linear interaction analysis (LIA) theory. The shock refracts the vorticity wave and generates additional acoustic and entropy waves in the downstream flow. The characteristics of the downstream waves are a function of up-stream wave amplitude, wave orientation, and Mach number. Our main motive here is to quantify the non-linear effects outside the limits of LIA as a function of these basic parameters theoretically. We perform high order accurate numerical simulations of the full non-linear Euler equations for this problem. RMS error(σ) for the deviation between LIA and high order numerical solution is studied. Results are presented with respect to the variation in fluctuation intensity, wave orientation, and Mach number. The σ is observed to increase with an increase in fluctuation intensity, wave orientation, and Mach number. We present a weakly non-linear analysis of the vorticity amplification at the shock wave. Predictions from the analysis are found to agree with σ variation for the given set of parameters. The results from the analysis for vorticity are used to corrobo-rate the observations. Using weakly non-linear analysis, we discovered σ to scale with the square of the mean compression ratio across the shock for a given upstream orientation of the elementary waves.