Large eddy simulation and self-similarity analysis of the momentum spreading in the near field region of turbulent submerged round jets

Numerical simulation and self-similarity of the mean mass transfer in turbulent round jets

“…In the past few years, we investigated numerically both the momentum and the passive scalar spreading in turbulent submerged jets. The momentum spreading in the NFR of turbulent round jets is found self-similar in [1]. The passive scalar spreading of turbulent rectangular jets is found self-similar in the URF and PCR, [20].…”

“…The threedimensional (3D) grid is generated with blockMesh, the OpenFOAM utility for mesh generation. Full details of the computational grid are reported in [1] and omitted here for shortage of space. The nozzle diameter is 5 mm and the nozzle lip thickness 1.8 mm.…”

“…The dimensionless grid stencils in the jet boundary layer are reported in Table 2, as mean value and standard deviation, because grid is not uniform and momentum thickness increases with the distance from the nozzle. The full grid validation is reported in [1], where the grid is analyzed in terms of the following variables: i) ratio between sub-grid viscosity and laminar viscosity; ii) ratio between sub-grid kinetic energy and turbulent kinetic energy; iii) ratio between local grid stencil and Kolmogorov length scale; iv) turbulence energy spectra. A flat velocity profile is imposed on the nozzle exit, similarly to the experiments of [29], and previous numerical investigations [13,[30][31].…”

“…Replacing the expressions found in [1] for u and v, and expressing the derivatives of the self-similar variable in terms of the axial coordinate, we obtain:…”

“…Selfsimilarity (or self-preservation) is a property of the field occurring when its profiles can be brought into congruence by coordinates-dependent scale factors. This concept has been used to describe the momentum spreading in turbulent jets, with the Boussinesque hypothesis [1][2][3][4][5][6][7], or without [8].…”