Simulation Of Multi-Physics Coupling Based On The Theory In Porous Media

There is porous media throughout in the natural,industrial,agricultural and other fields,it exists everywhere.The transmission process of energy and quality in porous media is the basic element of natural phenomena or manufacturing or our daily lives,although basic,but extremely complex.Because a variety of physical field coupling,known or unknown in porous media is countless.It is also the intersection of multiple disciplines at the same time.Because of its extremely wide range of applications,the transmission mechanism in porous media is of great value.In this paper,a new mathematical model is developed to explore the multi-field coupling transmission process in porous media based on the mature research model of multi-physics field of porous media established by predecessors.The concrete approach is as follows:By studying the existing one-dimensional and one-half coupled heat and moisture transfer model,a two-dimensional model of full coupling of heat and moisture deformation in concrete was established based on Fick's second law,Fourier's law and elastic constitutive equation.On this basis,COMSOL multiphysics simulation software was used to simulate the thermos-hydro-mechanical coupling of concrete through its PDE module,and the temperature and content of the concrete in different time steps,moisture distribution,the overall deformation,the overall average drying curve were obtained.The numerical simulation results of this paper are compared with the experimental data and the results of the one-dimensional model to verify the correctness of the model,and the two-dimensional coupled model is used to analyze the relationship between ambient temperature and air relative humidity for the coupling of heat and moisture influences.The analysis results show that the concrete samples based on the property of porous media have little change in moisture content during the heat-moisture coupling deformation,but the temperature changes obviously.By comparing the temperature and moisture content of concrete specimens under different environmental conditions,it is concluded that the internal temperature change of concrete specimens is affected by a certain degree of ambient temperature,which is basically unaffected by the relative humidity of air.The internal moisture content of concrete specimens is less affected by the ambient temperature and more less affected by the relative humidity of the air.The change of the length of the concrete specimens is only affected by the ambient temperature,which has nothing to do with the relative humidity of the air.Based on Fick's second law,Fourier's law and the elastic mechanics constitutive equations considering the factors of temperature and humidity,the hot-air drying problem of porous media of fruits and vegetables was studied.Taking potatoes as an example,expanding the dimension of existing mathematical model,then with the simulating from COMSOL,the results were compared with the data in the literature toverify the feasibility of the model.Finally,by comparing the temperature and moisture content of potato slices under different environmental conditions,it is confirmed that ambient temperature has a greater impact on the energy transfer of potato slices,and also has some impact on the mass transfer;while the relative humidity of air has little effect on the energy transfer of potato slices,The impact of quality transmission is also limited.