Results from numerical simulations and guidance from an approximated corrected-theory, developed by Oliveira and Pinho (1997), (Oliveira, P.J. and Pinho, F.T. 1997. Pressure drop coecient of laminar Newtonian ̄ow in axisymmetric sudden expansions. Int. J. Heat and Fluid ̄ow 18, 518±529) have been used to arrive at a correlation expressing the irreversible loss coecient for laminar Newtonian ̄...

Abstract We performed a characterization of the bubbly and slug flow regimes in minichannels in conditions relevant to microgravity. Two-phase flows were generated on ground by means of a T-junction device (1 mm i.d.), whose operation is independent to changes in gravity level [1]. Air and water were injected at several superficial velocities ranging from 0 up to 2 m/s. The generation and detac...

NGC 1275 in the centre of the Perseus cluster of galaxies, Abell 426, is surrounded by a spectacular filamentary Hα nebula. Deep Chandra X-ray imaging has revealed that the brighter outer filaments are also detected in soft X-rays. This can be due to conduction and mixing of the cold gas in the filaments with the hot, dense intracluster medium. We show the correspondence of the filaments in bot...

Recent DNS studies of buoyant bubbly flows in vertical channels are discussed. Simulations of nearly spherical bubbly flows in vertical channels show that the bubbles move towards the wall for upflow and away from the wall for downflow in such a way that the core is in hydrostatic equilibrium. For downflow the wall layer is free of bubbles but for upflow there is an excess of bubbles in the wal...

We present a theoretical analysis and experimental demonstration of particle trapping and manipulation around optothermally generated bubbles. We show that a particle located within 500 μm of a surface bubble can be attracted towards a bubble by drag force resulting from a convective flow. Once the particle comes in contact with the bubble's surface, a balance between surface tension forces and...

Quasi-static and dynamic stall control experiments, using dielectric barrier discharge plasma actuators, were performed on a square-tipped aspect-ratio-one wing, with NACA 0015 profile, under harmonic pitching, at Reynolds number of . Relatively low relatively high pulse-modulated reduced excitation frequencies introduced the leading edge; former produced largest poststall lift improvements, wh...

Direct numerical simulations (DNS) are conducted of flow through a linear low-pressure turbine cascade with T106 blade sections at Re=60,000, based on chord and isentropic exit velocity. A highly efficient in-house compressible Navier-Stokes solver was adapted for turbine cascade simulations and applied to investigate the effect of inflow disturbances on transition behaviour and blade profile l...

In the present study, aerodynamic performance of horizontal-axis wind turbine blades by considering flap-wise oscillations are numerically investigated using direct numerical simulations (DNS). The details flow structure can be analysed and predicted performing DNS over an oscillating blade realistic behaviour with natural vibration frequencies. this impact vibrations on separation point, lamin...

Leading-edge inflatable (LEI) kites use a pressurized tubular frame to structurally support single skin membrane canopy. The presence of the tubes on pressure side wing leads characteristic flow phenomena for this type kite. In paper, we present steady-state Reynolds-Averaged Navier-Stokes (RANS) simulations LEI airborne wind energy applications. Expanding previous work where only leading-edge ...