Viscous microdetonation physics

Viscous and diffusion effects on the propagation of detonations in micron-sized channels are investigated by means of numerical calculations of the Navier-Stokes equations. It is shown that an initial ZND (Zeldovich, Neumann, Doring) supersonic combustion wave becomes unstable. Distinct galloping detonation waves characterized by deviations from the inviscid dynamics propagate at different distances from the walls of the channel. The deviations include enhanced maxima in the front's pressure and multiple ignition. For the larger Reynolds numbers studied (Re=2400), the geometry and speed of the front are affected by the propagation of transverse waves. The latter are responsible for the formation of periodic in time patterns in the graphs of maximal pressure. For smaller Reynolds numbers (Re=240), the patterns are damped by viscous processes. Although occasionally the front weakens significantly during its periodic dynamics, the detonation is not quenched; its speed is non-uniform, sometimes been higher close to the wall, other times been higher close to the centerline