Hydrothermal Coupling Analysis of Freezing Process of Black Soil Farmland Profile Based on COMSOL Model
To quantitatively analyze the coupling characteristics of water and heat in the profile of typical black soil cultivated land during the freezing process,the topsoil in the typical black soil region in NE China was taken as the research object.Through indoor single soil column simulation experiments and combination with COMSOL Multiphysics model PDE module,the coupling solution of temperature field and moisture field during black soil freezing process was achieved.Results showed that:(1)The COMSOL model could realize the hydrothermal coupling analysis of the freezing process of black soil profile,and the fitting effect of temperature field(R2=0.83,RMSE=0.91℃)and water field(R2 =0.88,RMSE=0.02 cm/cm3)was good,which could meet the fitting accuracy requirements.(2)The temperature change rate of black soil cultivated land profile exhibited a trend of rapid cooling followed by a slow approach to stability,and the closer to the cold end,the faster the rate at which soil temperature decreased to the stability stage.(3)The frozen black soil cultivated land profile underwent significant water redistribution during the freezing process.An ice crystal aggregation phenomenon was observed at the warm end,which occured at a fast rate[0.000 93～0.001 00 cm/(cm3·h)],while the cold end showed the opposite phenomenon[0.000 34～0.000 42 cm/(cm3·h)].The research results can provide technical support for analyzing the water heat transport law of frozen black soil,as well as a theoretical basis for the study of the mechanism of frozen thawing and hydraulic composite erosion of black soil profiles and dynamic simulation of water-heat in profiles.
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