Direct numerical simulations are performed to predict the three-dimensional unsteady flow interactions in the near-field of a square jet issuing normal to a cross-flow. The simulated flow features reveal the formation of an upstream horseshoe vortex system, which is the result of an interaction between the oncoming channel floor shear layer and the transverse jet; the growth of a sequence of Ke...

Simultaneous dual-plane PIV experiments were performed in streamwise-spanwise planes in the log region of a turbulent boundary layer at a moderate Reynolds number (Reτ ∼ 1100). The acquired datasets were used to resolve all 9 velocity gradients from which the complete vorticity vector and other invariant quantities like 3-D swirl strength were computed. These derived quantities were used to ana...

We present experimental heat transport measurements of turbulent Rayleigh-Bénard convection with rotation about a vertical axis. The fluid, water with a Prandtl number (sigma) of about 6, was confined in a cell with a square cross section of 7.3 x 7.3 cm2 and a height of 9.4 cm. Heat transport was measured for Rayleigh numbers 2 x 10(5)<Ra<5 x 10(8) and Taylor numbers 0<Ta<5 x 10(9). We show th...

In this paper an efficient split-type Finite-Difference (FD) scheme with high modal resolution – most important for the streamwise convection terms that cause wave transport and interaction – is derived for a mixed Fourier-spectral/FD method that is designed for the spatial direct numerical simulation (DNS) of boundary-layer transition and turbulence. Using a relatively simple but thorough and ...

Cavity flows occur in a wide range of low-speed applications (Mach number ?0.3), such as aircraft wheel wells, ground transportation, and pipelines. In the current study, steady jet is forced from cavity leading edge at different momentum fluxes (0.11 kg/ms2, 0.44 kg/m·s2, 0.96 kg/m·s2). The investigation was performed for an open with length to depth ratio 4 Reynolds based on approximately 50,...

Noise generation is investigated in subsonic isothermal round jets at Mach numbers M =0.6 and M =0.9, with Reynolds numbers ReD =1700 and ReD 10, using causality methods on data provided by large-eddy simulations. The correlations between broadband sound pressure signals and broadband turbulence signals along the jet axis and the shear layer are calculated. The normalized correlations are found...

In an open channel, a hydraulic jump is the rapid transition from superto sub-critical flow associated with strong turbulence and air bubble entrainment in the mixing layer. New experiments were performed at relatively large Reynolds numbers using phase-detection probes. Some new signal analysis provided characteristic air–water time and length scales of the vortical structures advecting the ai...

This paper presents an investigation on the effect of introducing large-scale roughness through static curvature modifications on the low speed flow over an airfoil. The surfaces of a standard Eppler 398 airfoil have been modified with regular perturbations or “bumps” of the order of 2%c for this purpose. While the actual E398 airfoil is not a suitable candidate for low Re cases due to extensiv...

Subjecting a boundary layer to sudden or changing strain can have a profound effect on the flow. In turbulent boundary layers, oscillating the wall has been shown in previous studies as a viable mechanism to reduce drag. At lower Reynolds numbers, and in particular in the transition regime, the flow response is complex. On the one hand, the three dimensionality of the base state can lead to new...