Numerical simulation of propagation of small perturbations interacting with flows and solid bodies

CFD-CAA Coupled Calculations of a Tandem Cylinder Configuration to Assess Facility Installation Effects

“…Because the grid was generated analytically, smoothness of the grid and metrics could be assured to be greater than the order of the CAA solver. Although the grid was not systematically refined, the grid spacing was chosen to resolve the important range of frequencies in the problem based on the demonstrated resolving capability of the CAA code 4,5,16 . Furthermore, some grid sensitivity studies were performed, and the results were found to be relatively insensitive to refinement beyond the grid spacing used in this study.…”

“…All the CAA calculations were conducted with ONERA's sAbrinA.v0 solver [3][4][5][6][7][16][17][18] , using NASA computational resources. sAbrinA.v0 is a structured grid, time-accurate CAA code that solves the full Euler equations, either in a conservative form or non-conservative, perturbed form (with a splitting of the complete variables into a 'frozen' mean flow and a 'fluctuating' perturbation).…”

An advanced hybrid method for the acoustic prediction

“…The latter technique consisted in forcing explicitly the CAA computed field with the acoustic signal to be transferred, such explicit forcing being applied at each time step and over a few rows of ghost cells (see details in Refs. [17,18]). As is, such an interface technique was not only straightforward to implement and use, but it was also general enough to be applicable to many situations of interest.…”

“…Within this framework, several dedicated studies were achieved, which all served the same purpose, whilst focusing each on a particular aspect of the problem; besides previous works that led to the development of an optimal CAA method/solver [17,18], a specific research action [22][23][24] consisted in developing a weak coupling approach that could allow a CAA-based propagation stage to be forced with any given acoustic signal whilst offering to handle acoustic backscattering phenomena, for the overall hybrid method is compatible with many situations of interest (cf. the anechoicity requirement evocated above).…”

“…This weak coupling approach relies on the so-called Non Reflective Interface (NRI) technique [22][23][24], which constitutes an improved version of the original (reflective) interfacing technique that had been initially developed by the present first author a decade ago [17,18]. The latter technique consisted in forcing explicitly the CAA computed field with the acoustic signal to be transferred, such explicit forcing being applied at each time step and over a few rows of ghost cells (see details in Refs.…”