An efficient immersed boundary projection method for flow over complex/moving boundaries

A revised immersed boundary projection method with the primitive variables is proposed. The pressure and the momentum forcing are regarded as multipliers for enforcing the divergence-free constraint of the flow field and the no-slip condition along the immersed boundary. An efficient computation algorithm is developed by utilizing a two-step approximate factorization, so that only little modification to the original Navier-Stokes solver is needed and the additional computational cost due to calculation of the momentum forcing is small. Three computation sequences derived from the different factorization processes are introduced and compared. The temporal and spatial accuracies are found to be between the first and second orders. Both two- and three-dimensional benchmark problems are examined for validation of the proposed method for flow over complex/moving boundaries. Flow over a flying three-dimensional dragonfly model with real morphology is also simulated as an application to the complex insect flight problem. (C) 2016 Elsevier Ltd. All rights reserved..