Parametric investigation of Rayleigh–Taylor instability under experimental conditions with the lattice Boltzmann method

In this paper, we explore the Rayleigh–Taylor instability (RTI) considering experimental conditions from open literature. In the simulations real properties are considered, facilitated by the dimensional lattice Boltzmann method. First, the numerical solution is validated with the experimental reference. Usually in the literature RTI is employed as a benchmark, comparing their solutions with some numeric or experimental reference. However, not always the same fluid properties are used, only the same Reynolds (Re) and Atwood (At) numbers are kept equal and the comparison is made using a dimensionless timescale. The linear theory already suggests that fixing these two dimensionless numbers may not be enough to guarantee similarity of the results. So, in this paper, we perform a parametric analysis to explore the validity of these two numbers and the impact of some components of Re on the RTI. The results yielded a different flow pattern under equal Re and At numbers, showing that they are not enough to obtain similarity. Also, the influence of Re number changes significantly depending on which parameter is changed for varying Re. Finally, on the basis of linear theory, we propose a new set of nondimensional parameters for the RTI similarity: Re, At, and Eo (Eötvös), which also accounts for the surface tension impact. Simulations are performed to verify this proposition, showing that the proposed set of dimensionless numbers is effective for surface tension values up to certain limit, which depends on the studied case.