Reliable Damping of Free Surface Waves in Numerical Simulations

TL;DR

This paper introduces a scalable method for damping free surface waves in Navier-Stokes simulations, ensuring reliable wave damping across different scales by adjusting damping coefficients based on wave parameters.

Contribution

It presents a new scaling law for selecting damping coefficients that ensures similarity between model and full-scale simulations, improving the reliability of free surface wave damping.

Findings

Scaling law enables consistent damping across scales

Optimal damping setup can be efficiently estimated

Damping coefficients must be adjusted for each simulation

Abstract

This paper generalizes existing approaches for free-surface wave damping via momentum sinks for flow simulations based on the Navier-Stokes equations. It is shown in 2D flow simulations that, to obtain reliable wave damping, the coefficients in the damping functions must be adjusted to the wave parameters. A scaling law for selecting these damping coefficients is presented, which enables similarity of the damping in model- and full-scale. The influence of the thickness of the damping layer, the wave steepness, the mesh fineness and the choice of the damping coefficients are examined. An efficient approach for estimating the optimal damping setup is presented. Results of 3D ship resistance computations show that the scaling laws apply to such simulations as well, so the damping coefficients should be adjusted for every simulation to ensure convergence of the solution in both model and full scale. Finally, practical recommendations for the setup of reliable damping in flow simulations with regular and irregular free surface waves are given.