  The paper performs simulation of a rectangular plate excited by turbulent
channel flow at friction Reynolds numbers of 180 and 400. The fluid-structure
interaction is assumed to be one-way coupled, i.e, the fluid affects the solid
and not vice versa. We solve the incompressible Navier Stokes equations using
finite volume direct numerical simulation in the fluid domain. In the solid
domain, we solve the dynamic linear elasticity equations using a time-domain
finite element method. The obtained plate averaged displacement spectra
collapse in the low frequency region in outer scaling. However, the high
frequency spectral levels do not collapse in inner units. This spectral
behavior is reasoned using theoretical arguments. We further study the sources
of plate excitation using a novel formulation. This formulation expresses the
average displacement spectra of the plate as an integrated contribution from
the fluid sources within the channel. Analysis of the net displacement source
reveals that at the plate natural frequencies, the contribution of the fluid
sources to the plate excitation peaks in the buffer layer. The corresponding
wall-normal width is found to be $\approx 0.75\delta$. We analyze the
decorrelated features of the sources using spectral Proper Orthogonal
Decomposition (POD) of the net displacement source. We enforce the
orthogonality of the modes in an inner product with a symmetric positive
definite kernel. The dominant spectral POD mode contributes to the entire plate
excitation. The contribution of the remaining modes from the different
wall-normal regions undergo destructive interference resulting in zero net
contribution. The envelope of the dominant mode further shows that the location
and width of the contribution depend on inner and outer units, respectively.
