This paper presents the application of the open source non-hydrostatic wave-flow model SWASH to propagation of irregular waves in a barred surf zone, and the model results are discussed by comparing against an extensive laboratory data set. This study focus not only on wave transformation in the surf zone, but also on the numerical prediction of undertow and vertical distribution of turbulence levels under broken waves. Present simulations demonstrate the overall predictive capabilities of the model in computing breaking surf zone waves.