• A new numerical method based on a porous medium physical model is proposed to simulate wind fields behind porous windbreaks for high-speed railways.
• The method transforms the porosity–windproof performance matching problem into a relationship between the resistance coefficient and train aerodynamic loads.
• The influence of hole type on the wind field is examined, and explicit relationships among resistance coefficient, porosity, and aerodynamic loads are established.
• The porous media model effectively replaces geometrical windbreak structures in aerodynamic simulations, offering a simplified and efficient approach for engineering design.