Numerical Modeling Of Radon In Layer Stratum Medium

Radon comes from soil and rocks, therefore the contribution and transportinglaws of radon are important for the research on radon in houses and surrounding radon.Because of the complexity of geology, radon concentration are various, many kinds ofnumerical modeling of radon are restricted to easier geology and ignore effect ofconvection. Actually medium is not infinite, it has been divided into many layersbelow the surface. The transport of radon in each layer is different, this paper get atwo-layer modeling of radon by analyzing radon's transport in these conditions.This paper first simply introduces the characters, sources and transporting lawsof radon in the medium, and then analyses the influential factors of radon transportand find out their meanings in the model. We begin with Fick's law, Darcy's law andradon's decay in the process of simulating the model, set up transporting equation ofradon in the steady state and get the universal result of differential equation. We canfind out the right boundary condition by analyzing every influential factor in thenumerical modeling and get the right two-layer numerical modeling. Assuming theparameters in the medium are same, the graph of the change of radon concentrationalong with depth overlaps the graph of radon concentration along with depth in thehomogeneous material up to the surface, we know the correctness of the model in theacademic condition. After that we discuss these parameters which influence thetwo-layer numerical model, for example coefficient of diffusion, velocity ofconvection, porosity and the depth of interface. The influence on the two-layernumerical model is discussed by writing Matlab program to construct graph. As aresult of variety of season, the change of weather condition bring on the change ofmedium's state, the paper discusses the variety of radon concentration before the rainand after the rain. Sometimes superficial soil is covered with rain or snow, finally wesimulate radon's transport condition in the medium after superficial soil is coveredwith rain or snow.