The effect of material compliance on turbulence–viscoelastic wall interactions

We perform direct numerical simulations of turbulent flow over compliant walls, across a range of material stiffnesses. The material properties are selected such that the shear-wave speed ranges from well below to well above the bulk velocity. For soft materials, we observe strong two-way coupling between turbulence and the compliant walls, and the deformation is primarily two dimensional and has large amplitude. As the material stiffness increases beyond a critical threshold, the deformation becomes three dimensional with small amplitude. This trend is explained with aid of two-dimensional simulations of material characterization, where we apply streamwise-traveling stress at the surface. The characterization captures the large two-dimensional wave response of soft materials, and significant damping of these waves above the critical stiffness. The impact of material compliance on the turbulence and wall-pressure spectra will also be discussed.