Surrogate wall modeling for large-eddy simulations with diffuse-interface immersed boundary method

The diffuse-interface immersed boundary method has rarely been used in the large-eddy simulation of wall-bounded turbulent flows despite its efficiency and robustness in handling walls. The primary shortcomings of the method are the unavailability of explicit reconstructions of velocities and the low fidelity of interpolations contaminated by the diffuse-interface. We propose a surrogate wall model to circumvent these shortcomings. Its main features are (1) to construct a Lagrangian surrogate layer near the wall to introduce explicit reconstructions of velocities, (2) to reconstruct the velocities at the surrogate layer using a near wall model, and (3) impose the immersed boundary method on the surrogate layer instead of the wall to reduce the undesirable effects of the diffuse-interface on flows. The surrogate wall model is used to simulate the canonical plane channel flows at different Reynolds numbers and further tested against flows over periodic hills. The results obtained are in agreement with those of boundary-conformal mesh and/or sharp-interface immersed boundary method.