We demonstrate a novel strategy for mixing solutions and initiating chemical reactions in microfluidic systems. This method utilizes highly focused nanosecond laser pulses from a Q-switched Nd:YAG laser at lambda = 532 nm to generate cavitation bubbles within 100- and 200-microm-wide microfluidic channels containing the parallel laminar flow of two fluids. The bubble expansion and subsequent co...

The impact of shock waves on supersonic cooling films is studied using large-eddy simulations (LES). A laminar cooling film is injected through a slot at a Mach number Mai = 1.8 into a fully turbulent boundary layer at a freestream Mach number Ma∞ = 2.44. The cooling film is disturbed by oblique shock waves at deflection angles of 5° and 8° at two downstream positions of the slot. At shock impi...

A NUMBER of military and civilian applications require efficient operation of airfoils in low chord Reynolds numbers. The applications include propellers, sailplanes, ultralight mancarrying/man-powered aircraft, high-altitude vehicles, wind turbines, unmanned aerial vehicles, and micro air vehicles. Careful management of boundary layers on low-Reynolds-number airfoils is required to alleviate t...

A parametric investigation of the influence a small cylinder on laminar separated boundary layer over NACA0012 wing is performed using numerical simulations. The (γ - Reθ,t) steady RANS transitional model first validated in capturing separation baseline suction surface. effects three rod diameter ratios (d/c = 0.67%, 1.33% and 2%) bubble aerodynamic performances were examined. qualitative analy...

The flow around a circular arc is governed by the effect of sharp leading edge and arc's curvature. There range incidences where leading-edge separation bubble (LESB) formed on convex side arc, reattached boundary layer separates further downstream. Akin to foils cylinders, for increasing values Reynolds number, turns from laminar turbulent resulting in step change forces, here termed force cri...

We compute the probability distribution of the invariant separation between nucleation centers of colliding true vacuum bubbles arising from the decay of a false de Sitter space vacuum. We find that even in the limit of a very small nucleation rate (ΓH−5 ≪ 1) the production of widely separated bubble pairs is suppressed. This distribution is of particular relevance for the recently proposed “co...

Hypersonic laminar flow over a canonical 25°–55° double cone is studied using computational fluid dynamics and global stability analysis (GSA) with free-stream Mach number of 11.5 various unit Reynolds numbers. Axisymmetric simulations reveal that secondary separation occurs beneath the primary bubble beyond critical number. The numerical results agree well existing experiments triple-deck theo...

Effect of forcing using a modeled zero-net mass-flux (ZNMF) jet on a stalled NACA 4418 airfoil at Rc=40,000 is examined using two-dimensional numerical simulations. The baseline uncontrolled simulations are modeled after the experiments of Zaman & Culley. The simulations indicate that the stalled airfoil is subject to three naturally occurring frequencies corresponding to the shear layer, the s...

Flow visualization by the schlieren technique in the neighbourhood of a fully developed cavity on two axisymmetric headforms has shown the existence of laminar boundary-layer separation upstream of cavitation separation, and the distance between the two separations to be strongly dependent on Reynolds number. Based on present results, a semi-empirical method is developed to predict the position...