Numerical Simulation Of Turbulent Flow Characteristics On Two-dimensional Rough Wall

The flow on the near-surface wall is one of the most important research topics in the field of blown sand physics and structural wind engineering.The description of the near-wall flow field structure can correctly understand and predict the behavior of the fluid,so the study of the near-wall surface flow field structure is very critical.Therefore,the research works of this article are as follows:1.This paper briefly reviews the current research status of turbulence characteristics and nearsurface flow field structure of fluids flowing through the near surface by scholars at home and abroad,and summarizes and analyzes them from three aspects: theoretical research,numerical simulation and wind tunnel test;2.Aiming at the rough walls such as buildings,vegetation layers,grass squares and stone squares existing in nature,a simplified discrete rough element model is proposed for numerical analysis.It is calculated that the differential form drag coefficient reaches the maximum value when the distance and height ratio of the adjacent rough elements is 7;Through the calculation of the skin friction coefficient,the position of the flow field reattachment point is obtained,and this value is consistent with the existing results.The aerodynamic roughness length and zero-plane displacement height are calculated based on the flow resistance,and it is found that the aerodynamic roughness length reached the maximum at a distance and height ratio of 6;3.For the undulating topography and landform of sand ripples,sand dunes,etc.,it is simplified as a continuous cosine function-like continuous rough element model,and numerical analysis of the rough wall surface is performed.The results show that the differential form drag coefficient decreases with the increase of the wavelength and amplitude ratio.By analyzing and calculating the skin friction coefficient on the wall surface of the wavy wall,the position of the separation point and reattachment point where the tail vortex falls behind the peak is obtained.The zero-plane displacement height and aerodynamic roughness length on a rough wall composed of continuous rough elements can be calculated from the flow resistance.Under different Reynolds number,the form drag coefficient,skin friction coefficient and zero plane displacement height decrease with increasing wind speed;Through the calculation and analysis of the rough wall composed of two kinds of different rough elements,it is found that the numerical simulation method can describe the flow field characteristics and flow field structure of the fluid flowing through the near wall surface and provide a certain basis for engineering practice.