Direct numerical simulations of turbulent mixing in a channel with two splitter plates

Turbulent mixing processes are of great importance in reacting flows owing to the fact that turbulence induces reactants to mix rapidly thereby increasing the reaction rate. A turbulent mixing flow exhibits complex dynamic behavior and the advec-tion of a passive scalar by the same flow reveals many phenomenological parallels with the behavior of the velocity field. Direct numerical simulations are performed for the evolution of a mixing layer in a channel with two splitter plates at the inlet, for the first time. A splitter plate configuration is a well-studied geometry, known to induce mixing as a result of the Kelvin-Helmholtz instability in shear layers. The transport of a conserved passive scalar is examined to assess the mechanisms of entrainment and mixing within the shear flow. The scalar probability density functions are evaluated to trace the evolution of the mixing layer along the streamwise direction. Solutions are obtained from the time-dependent Navier-Stokes equations by means of an artificial compressibility formulation with dual-time stepping.