THE EFFECT OF PERMEABILITY ON WAKE CHARACTERISTICS BEHIND STRUCTURED POROUS CYLINDERS

This study experimentally investigates the wake structure of a porous square cylinder, emphasizing permeability across a broad range of Da (i.e., 2.4 × 10⁻⁵ < Da < 2.9 × 10⁻³). With a simple cubic lattice configuration, the cylinder was produced using advanced additive manufacturing techniques. By combining this technique with a periodic and scalable lattice design, permeability was effectively separated from porosity, allowing for an in-depth parametric study. The primary parameter, permeability, was determined by measuring the pressure drop and superficial velocity for each porous disk within an open-loop pipe flow system. Standard planar particle-image velocity (PIV) measurements in an open-loop wind tunnel captured downstream wake characteristics. The data provided insights into structural alternation in the near-wake related to permeability, revealing four distinct flow regimes based on Da. Additionally, the internal flow adjustment length (L_i) was examined by incorporating a permeability-based source term into the momentum equation, leading to the development of an analytical model for L_i. The experimental results validate this model, highlighting L_i as a characteristic length scale in the near-wake.