The experimental analysis of eddy viscosity conducted by Oldekop et al. (2019), which incorporates Reynolds stresses, modified mean velocity, its gradients, and turbulent kinetic energy, is revisited for a plunging breaker wave and integrated into the present numerical modelling framework. Surface waves with a 2-second period were generated in an experimental flume measuring 22 meters in length and 0.6 meters in height, with a water depth of 0.3 meters. These waves approached a sloping bottom and broke on a constant slope of 1:17. The same periodic plunging breaker is numerically simulated for approximately 40 wave periods. The eddy-viscosity formulation is subsequently incorporated into a wave model, and the results are compared with those from a Reynolds-Averaged Navier-Stokes (RANS) solver employing an air-water interface model. Experimental results demonstrate that eddy viscosity beneath a plunging wave over a sloping bottom exhibits more complex variation throughout the wave cycle and water column than is typically considered in coastal engineering wave models. The computational fluid dynamics model used in this study is based on the volume-of-fluid approach with an interface-tracking method. In this model, the previously used Smagorinsky turbulence model is replaced by a k-epsilon turbulence model. Experimental findings are compared to numerical results for a plunging breaker in the surf zone, where air and water are mixed.