Compliant Material Coating Response to a Turbulent Boundary Layer

We describe results of transient two-dimensional finite element computations used to simulate elastic and visco-elastic surface response to the stress generated by the surface turbulent boundary layer in water. We are characterizing the temporal and spatial response of soft, pliable surface coating materials such as natural rubbers, artificially treated rubber-like compounds, and cured polymeric gels. We examine a variety of coatings from stacked homogeneous layers to internally structured layers with open and fluid filled cells or with directional ribs and channels. In addition, we examine non-linear visco-elastic loss characteristics and time-dependent influences on material response. Our goal is identifying drag and characterizing the most important dynamic material properties to achieve this end. Two dimensional transient numerical computations are applied to simulate the space and time random scalar pressures which excite the material response. (Author) Prepared in cooperation with Old Dominion Univ., Norfolk, VA.