Lattice-Boltzmann modeling of unstable flows amid arrays of wires

A lattice-Boltzmann model (LBM) of unstable flows amid easily permeable obstructions consisting of regular arrays of wires is presented. The obstacles are modeled by forces incorporated as source terms in the LBM equation, following the same procedure as the immersed boundary method. Yet the present method differs from the latter in that the structure is represented by a volumetric array of fixed points. Also each structural point exerts reactive forces governed by the Darcy law, rather than by elastic kinematics. The model is validated against two experiments consisting of air flowing in a channel partially obstructed by arrays of wires, finding excellent agreement. The simulations reveal the formation of complex vortical structures amid the wired region, which can be of interest in understanding natural phenomena or practical applications.