Two-dimensional direct numerical simulations of a forced-ignition event in an initially quiescent mixing layer of hydrogen and air have been carried out at atmospheric pressure using detailed chemistry and mixture-averaged diffusion coefficients. Since control of the ignition location is known to be critical in DISI engines, this study primarily investigates the effect of initial spark placement within the flammability limits of hydrogen-air. Displacement and stabilization speeds of the propagating flame fronts have been computed along isocontours of water vapor representing 10% and 25% of the downstream equilibrium concentration. Following the period of spark energy-addition the flame kernel is observed to bifurcate into twin triple flame structures that subsequently propagate towards opposite sides of the domain along the stoichiometric line. The point of maximum heat release was found to remain on the lean side after the transient spark interlude. For all cases of successful ignition, transient spark effects are observed to dissipate within 0.2 milliseconds.
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