Nonlinear Spanwise Modulated Waves in Channel Flow

This paper presents results about laminar-turbulent transition due the temporal evolution of spanwise modulated wavetrain in plane Poiseuille flow. The proposal here was to understand the nonlinear regime using a constant Reynolds number, typical to channel flow, towards to interpretation of the transition phenomena in boundary layer flow. The adopted method to build results was Direct Numerical Simulation. The spanwise wavetrain was obtained by simulating the temporal evolution of a disturbance along of computational domain to the normal velocity component (v-velocity). After, the wavetrain was introduced in flow as an initial condition. A high order numerical code was developed and tested to the present study. The results indicated which the classical k-type intability dominates the flow transition to the chosen parameters. It occurred because oblique wave seeds were nonlinearly produced, prior to the secondary instability. The results were in sense those by 1 in the investigation of the production of subharmonic seeds in modulated waves, in order, which the production of seeds for secondary instability appears to be a general feature of modulated waves in wall bounded flows.