Semi-analytical calculation of pore-related parameters of wire/woven screens

Abstract

Wire/woven screens have a wide range of applications, from being used as simple mechanical screening device to nanoscreen wicking with nanofluids. The vast number of applications makes important to study these screens with high accuracy, to reduce errors in characterisation and performance predictions. Previous works to date focused either on the study of these screens as a two-dimensional surface (e.g. in ventilation openings as insect-proof screens) or as three-dimensional structures under important assumptions (symmetric mesh, thickness of two times their diameter, linear evolution of the pore area along the thickness). These incomplete modellings introduce errors in applications such as the estimation of permeability of the porous media (two-dimensional porosity is identical for two meshes with the same projected area of pore but different thickness) or computational simulations of ventilation in buildings/greenhouses, where these parameters are imposed as boundary condition. The present investigation shows a method to calculate three-dimensional pore related structural properties semi-analytically for the first time and for any plain square mesh. We found that when sweeping the mesh with a plane parallel to it there are up to six different zones or stretches which can be integrated by a piece-wise approach (here named Discretisation Method). Results demonstrated high accuracy in the calculation of three-dimensional porosity and constriction factor (a parameter that is calculated by integration over the pore volume). Due to the mathematical complexity in the method, a software (AeroScreen v1.0) is available to obtain pore-related structural parameters from diameters, separations and thickness of the screen.