04 Feb Linear Wave Packets
Linear Wave Packets
Plane Poiseuille flow
Figure 1. Localized wave packet in Plane Poiseuille flows with Re=1000. An impulsive initial condition, located at the channel mid-plane is obtained by linear superposition of 7380 waves. The longitudinal (α) and transversal (β) components of the polar wavenumber span the range [0,10] and [-10,10], respectively. The visualization represents the three components of the perturbation velocity after 60 time scales and at y=0.5. All the spatial coordinates are non-dimensional (the reference length is the channel half thickness), and the basic flow is from left to right [movie U] [movie V] [movie W]
Blasius boundary-layer flow
Figure 2. Localized wave packet in Blasius flow with Re=1000. An impulsive initial condition, located near the wall at (x,z)=(0,0) is obtained by linear superposition of 365 waves with polar wavenumber within the range [2.5± 3.8]. The visualization represents the longitudinal component of the perturbation velocity (top panel) and the perturbation kinetic energy (bottom panel) after 150 time scales and at y=0.5. All the spatial coordinates are non-dimensional (the reference length is the displacement thickness δ*), and the basic flow is from left to right [movie U] [movie V] [movie W] [movie E]
