Eighth Mississippi State - UAB Conference on Differential Equations and Computational Simulations. Electron. J. Diff. Eqns., Conference 19 (2010), pp. 235-244. Title: Numerical solution to nonlinear Tricomi equation using WENO schemes Authors: Adrian Sescu (Univ. of Toledo, OH, USA) Abdollah A. Afjeh (Univ. of Toledo, OH, USA) Carmen Sescu (Univ. of Toledo, OH, USA) Abstract: Nonlinear Tricomi equation is a hybrid (hyperbolic-elliptic) second order partial differential equation, modelling the sonic boom focusing. In this paper, the Tricomi equation is transformed into a hyperbolic system of first order equations, in conservation law form. On the upper boundary, a new mixed boundary condition for the acoustic pressure is used to avoid the inclusion of the Dirac function in the numerical solution. Weighted Essentially Non-Oscillatory (WENO) schemes are used for the spatial discretization, and the time marching is carried out using the second order accurate Runge-Kutta total-variation diminishing (TVD) scheme. Published September 25, 2010. Math Subject Classifications: 76Q05, 35L60, 35L65, 65M22. Key Words: Nonlinear aeroacoustics; hyperbolic conservation law; discretized equations.