Further improvements of the delta-LES-SPH model

This work presents novel studies and investigations regarding the SPH model presented in [1], where the SPH equations are rewritten within a Large Eddy Simulation (LES) framework. Compared with the original formulation, here the model is recast in a quasi-Lagrangian fashion and the fluid particles are moved by adding to the actual velocity a small deviation based on the Particle Shifting Technique (PST) described in [2]. Moreover, to avoid the formation of voids in the fluid regions characterized by high vorticity and negative pressure, the Tensile Instability Control (TIC) technique presented in [3] is also implemented. The combination of the particle shifting technique with the tensile instability control allows for a stable and robust numerical scheme, which is suited for the simulations of high Reynolds number flows typical of the LES approach. The proposed model is tested within a 2D framework, considering the evolution of a fluid at rest which is forced by an initial time window and, then, left free to evolve, generating freely decaying turbulence. The forcing used in the above problem mimics the formation of the vortex patches of the Taylor-Green problem. The results obtained with the proposed model are going to be compared with the solutions obtained from a Mesh-based Finite Volume Method.