Innovative flexible protection barriers against shallow landslides, made from high tensile steel meshes, demanded the development of numerical models for the different mesh types accompanied with 1:1 scale prototype field testing. To generate the barrier model, a special Discrete Element had to be developed that represents the chain link type of steel mesh. It was crucial that it includes the complex out-of-plane height of the mesh that accomodates the local high deformations of the net. The filling process of the barrier is simulated using OpenFOAM, taking the fluid-structure interaction with high deformations into account. In addition to the shear thinning behaviour of the mud, the turbulence in form of a large eddy simulation can be introduced, having regard to the interaction with the complex geometry and free surface by a Dynamic Mixed Model approach for the subgrid scales. The model is validated with 1:1 scale tests where shots of 50 m3 of mud travel down a 40 m long slope and hit the barrier.