We simulate the equations of linearized (around Poiseuille flow) 3D channel flow with
body force fields as inputs. With zero initial conditions, introduce a body
force which is a spatio-temporal
impulse near the bottom wall. Physically, this can be thought of as a concentrated
momentary "detonation" near the bottom wall. The pictures below show the development
of stream-wise vorticity and velocity thereafter. Note the striking resemblence to
some features of so-called "turbulnet spots" (e.g. the arrow head shape, span-wise
spreading, and alternating
stream-wise streaks and vortices). Keep in mind that these are the linearized Navier-Stokes
equations.
The details of this can be found in the paper:
The spatio-temporal impulse response of
the linearized Navier-Stokes equations on the publications page.
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