Investigation of Wall Function Effects on Aerodynamic Characteristics of Turbulent Flow Around a Simplified High-Speed Train

Abstract

Modelling of turbulence is a vital issue for flow forecasting which is of great interest for most of engineering applications like flow over planes, movement of pollutants and some industrial processes. Originally, via solving the government equations (Navier-Stokes equations) the flow field can be simulated. With developing PCs and high-performance computers, implementing of Navier-Stokes equations for numerical simulation is increasing. In this research, the effects of some wall functions on aerodynamic and turbulence behavior of air flow around a simplified high-speed train via OpenFOAM software are numerically investigated. In the following, first, the effects of some default and common wall functions of OpenFOAM on the flow and aerodynamic key parameters are analyzed and then, a relatively new wall function called “Enhanced Wall Function” was implemented from ANSYS FLUENT into OpenFOAM and improvement for comprehensive simulation. Variations of flow key parameters such as velocity, pressure distribution and aerodynamic significant components and parameters such as lift, drag and side coefficients under the influence of wall functions changes are illustrated. The results could be used for obtaining more accurate analysis of aerodynamic characteristics of fluid flow around high-speed trains.

Interaction Simulation of a Lateral Wall Distance on Aerodynamic Characteristics of a Simplified High-speed Train

“…Also, to decrease the harmful influences of crosswinds, the work attempted to find an optimum porous barrier design. Finally, Hajipour et al [30][31][32] in 2021 investigated the impacts of some wall functions on the airflow and aerodynamic properties of a simplified highspeed train using OpenFOAM. They studied the implemented wall function, known as the Enhanced Wall Function, which would be helpful in high-speed train aerodynamic simulations.…”

Aerodynamic Effects of High-Speed Train Positions During Tunnel Exit Under Crosswind Conditions Using Computational Fluid Dynamics

“…All these advantages, come at a cost. The aerodynamic performance of the train is strongly impacted by its speed, creating issues with operational performance and safety, especially when traveling near a tunnel [3][4][5][6][7][8]. Moreover, moving in the opposite direction of the wind provides a crosswind component on the item, increasing the apparent wind loads on the object [9][10][11].…”