CFD Study Of Wind Load Characteristics Of Slab-type High-rise Buildings

The study of wind field and wind effect has important guiding significance for wind-resistant design of high-rise buildings.The related study is always important in wind engineering area.When the airflow flows through the high-rise building,due to the inertia and viscosity of the airflow,the structure is subject to aerodynamic forces and complex fluid-solid coupling effects will be induced,including shear layer switching,airflow separation and reattachment,vortex formation and shedding,the flow wake transition and so on.In the present work,the computational fluid dynamics program OpenFOAM is used to simulate the two-dimensional cross-section and three-dimensional model of the slab building with different aspect ratios under various wind direction angles.The numerical results are compared with the wind tunnel test data.Firstly,the two-dimensional rectangular section of the building with zero wind direction angle is numerically simulated by using the Reynolds stress model k-epsilon model.With the increase of aspect ratio,the wind pressure coefficient and the drag/lift coefficients are reduced.Through the flow field analysis,it is because in large aspect ratio case,the vortex structures are stable attached to the surface of the building,leading to a week oscillation of wake.Then the large eddy simulation method is used to simulate the three-dimensional slab-type building at various wind angles.When h=2/3H,the drag and lift force coefficients are largest along the height direction of the building.With increase of wind angle,the drag coefficient is increased.While for the lift coefficient,the maximum value occurs at wind angle of 40° for ratio of building length to width L/W=4 and 10° for L/W-9.With high slap ratio,both the drag and lift coefficient are enlarged.Through the analysis of the three-dimensional flow field of the slab building,There are two vortex in the leeward side of building,the one in the high attitude are stable and it will deviate from the building at large wind angle,while the other one in the low position is easy to crush and reformed.With larger slap ratio,the vortex in the high attitude will become stronger while the one in the low position will decay.Moreover,all these vortex structures exist in the leeward of building with the length of 4W-8W..