A High-Fidelity Simulation Framework for Turbulent Flows with Complex (Metamaterial) Structures

We present a high-fidelity fluid–structure interaction framework based on a continuous-forcing immersed boundary method, integrated into a parallelized three-dimensional turbulent channel flow solver. The method is designed to handle a wide range of (sub)surface geometries, including complex metamaterial interfaces. We extend an existing strongly coupled IB-FSI formulation with new spatially discrete operators that enable information transfer between subsurface metamaterials and compliant IB patches. Several key modifications support this versatile functionality: a hybrid uniform–stretched grid to reduce the computational load, IB forcing to compute one-sided velocity gradients for accurate friction velocity, and parallelized IB operations aligned with the underlying flow solver’s domain decomposition. We demonstrate the method using five test cases: laminar cylindrical Couette flow; a parallel scaling test; and three turbulent channel flow configurations at a friction Reynolds number of 186, including a minimal flow unit with rigid walls, a channel with prescribed traveling wave–like wall deformations, and a channel with a compliant wall exhibiting rigid-body–like dynamics. The last test problem demonstrates the growing capability to handle arbitrary structures engaging in coupled dynamics with the flow, towards future investigations into fluid–metamaterial interaction.