The Study Of Inverse Problem In Urban Underground Road Pollutants Based On Inverse Problem Method

With the growing of urban traffic, urban underground roads have become an important means to alleviate urban transport problems. Due to the underground road space depressive, vehicle emissions is not easy to spread. And mainly through export or tower emissions to the atmosphere environment, is located in the city underground road emissions of pollutants. The diffusion level will directly affect the surrounding the environmental quality of residential area, such as administrative office or business district. So study and predict underground road pollutant diffusion model on urban underground road design has a guiding significance.Underground road air quality forecasting calculation, it usually takes a given initial conditions, boundary conditions and the concentration of the corresponding physical parameters to solve, this is the so-called pollutants diffusion calculation is the problem. The inverse problem refers to the measured results according to the pollutants to calculate unknown initial conditions, boundary conditions and physical parameters. In the control theory, the solution of the unknown object known as control variable, the corresponding inverse problem is called the control problem.Measured data contains abundant pollutant diffusion process information. If any model can be analyzed by using dynamic equation, the organic extract, the useful information in the measured information. This can be used to pollutant diffusion analysis and prediction, so it is possible to improve the model computing capacity, calculated in accordance with the actual most of the "real" pollutants concentration distribution. Based on this idea, within the framework of the inverse problem in this paper, based on the adjoint assimilation theory, set up about the concentration of the initial conditions, boundary conditions and physical parameters such as control variables of the inverse problem of pollutant diffusion dynamics model, through the dynamic model and the measured information fusion to improve the concentration of the initial conditions, boundary conditions and the accuracy of the physical parameters.Firstly, This article tested the Shanghai Yanan and the Changsha Yingpan road tunnel. Tested along the direction of motor vehicle quality of CO concentration distribution in tunnel, analyses the inside and outside traffic characteristics, the tunnel air conditions (temperature, wind speed), the environment quality, and the characteristics of tunnel structure (ramp, bend, fork), and other factors the influence the characteristics of the motor vehicle emissions laws.Second within the framework of the inverse problem, based on the partial differential equation of optimal control theory, established the dynamic model and observation information highway tunnel underground pollutants convection diffusion calculation model of the inverse problem, and the model solving method is given.The source item of the convection diffusion equation, for the inversion calculation, can be used to the inversion calculation of the source term pollutant concentration forecasted. Study shows that compared with the traditional is the problem of the model, the inverse problem of source term model inversion calculated from can reflect dynamic tunnel traffic, speed, comprehensive emission characteristics and so on factors, and calculate the pollutant concentration field precision more accurate. Using this method, through effective to using the observation data of all kinds of pollutants, can identify some uncertain parameters, which can better realize the analysis and prediction of the distribution of pollutant concentration.Finally, this paper calculated using the inverse problem of tunnel pollutant source term, combined with the proportion of road motor vehicle traffic, models, road geometry to calculate the tunnel motor bike emission factor. Explored in this paper, the inverse problem of the model in the actual application method.