Research On Scaled Simulation Of Atmospheric Flow In Urban Residential Quarters Considering Radiation

The CFD simulation of urban microclimate has very high requirements on the computing power and storage capacity of the computing platform,which is currently a key obstacle restricting its practical application.Exploring and improving calculation methods to improve calculation efficiency is important,which is an effective way to solve this problem,so that the CFD simulation can run on ordinary computer systems or small computing platforms.The research of this paper takes the urban microclimate CFD scale simulation simulation method under radiation conditions as the research object.Based on similarity theory,the similarity criteria that the scale and full-scale model need to meet are derived through equation analysis and dimensional analysis.The research doesn't follow the conditions of wind tunnel test.Instead,the physical parameters of the virtual flow medium are derived through the similarity criteria to ensure that the flow and the boundary conditions are similar.Based on the Fluent 19.0 platform,the accuracy of the turbulence model and radiation model used by the CFD simulation software is verified.The scale model is constructed according to the scale ratio of 1:4 and buoyancy effect caused by conduction,convection and radiation is considered in the working condition.The CFD simulation of the full scale and the model scale are performed and the accuracy,authenticity and validity of the simulation is judged by qualitative analysis and quantitative analysis.(1)Through qualitative analysis of the velocity,temperature and turbulent kinetic energy contour and velocity vector diagrams of the full-scale and scaled models,the results show that the fluid flow patterns and the temperature field distribution of the full-scale and scaled models are basically the same.The scale model maintains good similarity.(2)Quantitative analysis of wind pressure coefficient,dimensionless wind speed,dimensionless turbulent kinetic energy and dimensionless turbulence specific dissipation rate are performed on 14 measuring point sets near the building.The results show that through the fitting analysis of scaled and full-scaled simulation,the data of full scale and scale models fit well at most measuring points,and the change trend of variables between measuring points is basically the same.The scale simulation method can basically restore the flow characteristics of full-scaled flow accurately and effectively,which meets similar requirements.(3)Scale simulation can greatly improve calculation efficiency,reducing calculation time by 39.2% and reduce calculation memory usage by 32.7%.(4)In areas with high Reynolds number,such as roadway area and bypass area,the scale simulation error is relatively small.In areas with low Reynolds number,such as recirculation cavity area and building wake area,there are more measurement points with larger errors in scale simulation.Synthesizing all the measuring points,the error is roughly in the range of 0?10%,and there are only a few measuring points where the error is greater than 20%.