Structure resolved simulations of flow around porous coated cylinders based on a simplified pore-scale model

Abstract

Porous materials play a significant role in flow control and noise reduction of bluff bodies. The commonly used numerical macroscopic model cannot intuitively and accurately simulate the flow field and forces inside the porous material, while the direct numerical simulation using the microscopic model to resolve the complex structure of porous media requires massive computational resources. This study adopts a simplified microscopic porous model to simulate the flow around a porous coated cylinder (PCC) in the subcritical regime (at a Reynolds number of 8.2×104), and is expected to provide improved internal flow characteristics yet at reasonable computational costs. An array of small cylinders are regularly distributed around the large bare cylinder to mimic the pore structure in which the diameters of the small cylinders are varied to represent different porosities. The numerical simulation uses the k-ω Reynolds average turbulence model and the Ffowcs Williams-Hawkings (FW-H) acoustic analogy to calculate the flow and acoustic characteristics. Numerical results of this simplified microscopic model show that such an approximate PCC has significant effects on flow control and noise reduction, that bear strong similarity with other numerical methods and experimental results. Each model with different porosity reveals noise reduction relative to a bare cylinder. Flow field phenomena within the porous coating are revealed that help shed more light on those inside the realistic microstructures of porous media and the mechanisms of flow and noise control by PCCs.