Lattice Boltzmann based large eddy simulation of sweeping jet–crossflow interaction under varying skew angles

This study numerically investigates the interaction characteristics of a sweeping jet (SWJ) with a crossflow using the lattice Boltzmann method (LBM) coupled with large eddy simulation. The SWJ is generated by imposing an unsteady phenomenological boundary model and the flow field is resolved using a recursive regularised LBM combined with the Smagorinsky subgrid-scale model. The predicted unsteady and time-averaged flow fields show good qualitative and quantitative agreement with experimental data. The spatio-temporal characteristics of the SWJ–crossflow interaction are systematically analysed under various skew angles. The skew angle governs the interaction mode and associated vortex dynamics, where beta equals 90 Superscript ring β = 90 ∘ $\\beta =90^\\circ$ yields the largest spanwise penetration and strongest modulation of the counter-rotating vortex pair (CVP), beta equals 0 Superscript ring β = 0 ∘ $\\beta =0^\\circ$ produces maximum upstream and wall-normal penetration due to alternating alignment between the SWJ and crossflow over an oscillation cycle, and beta equals 45 Superscript ring β = 45 ∘ $\\beta =45^\\circ$ leads to an asymmetric intermediate state with weakened CVP formation. The penetration characteristics are further shown to depend on the opening angle and oscillation frequency, with the former enhancing normal penetration through momentum concentration and the latter modulating unsteady injection strength. The streamwise vorticity dynamics is dominated by a SWJ-induced vortex structure, whose strength increases with skew and opening angles but decreases with frequency, leading to a transition from CVP-dominated to quasi-steady behaviour in the time-averaged flow field. The double power law formulation successfully describes the maximum SWJ penetration due to the coexistence of upstream and normal momentum components, whereas the classical single power law fails.