Study on random wind pressure field of interfered building surface using HODMD and POD method
The wind pressure field on the surface of a interfered building is a complex,stochastic,high-dimensional dynamic system,and it is difficult to fully present and replicate the flow mechanism from the wind pressure distribution.Accompany with the wind tunnel test result of rigid model pressure measurement,the proper orthogonal decomposition(POD)method and high-order dynamic mode decomposition(HODMD)method are used to decompose and reconstruct the random wind pressure field on the surface of square high-rise building under the interference of tandem arrangement.The results show that the influence of the upstream building on the windward wind pressure of the downstream interfered building is mainly the shielding effect,which leads to the negative pressure area on the windward side of the downstream building,and the minimum mean pressure coefficient of the two side wind surfaces appears in the edge area close to the windward side.With the increasement of the upstream building placement distance,the shielding effect weakens,and the serial arrangement has little effect on the leeward wind pressure of downstream buildings.Through the analysis of POD method,it can be known that 3B(B is the windward width)is a critical gap of tandem arrangement,and when the interfered building located in the rear 3B from the interfered building,the interfered building has not obvious vortex shedding.The modes obtained by POD and HODMD can reflect the characteristics of fluctuating wind pressure,but because of the high nonlinearity of wind pressure data,POD modes reflect the coupling of multiple frequencies,while HODMD method can decompose the growth rate and frequency of each mode.The single-frequency HODMD mode can capture the coherent structure formed by the vortex motion of different scales on the building surface.The periodic change of the mode coefficient reflects the turbulent energy cascade.The low-frequency vortex motion dominates under four cases,of which are principle building and the windward width is 2B,3B and 4B.The interference of buildings increases the number of low-frequency modes containing high energy.HODMD method has more advantages in revealing the flow mechanism of the random wind pressure field.
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