The Research Of Effective Conductivity In The Porous Media

Porous media is a sort of multiphase space with solid framework.The transmission of quality,momentum and energy in porous media is a fundamental process happened in numerous natural phenomena,production and living.Heat conduction in porous media involves multiple scientific fields,draws people's attention to it increasingly.In addition,it has been researched and utilized for a long time.Nevertheless,due to the complicated structure of porous media,even when void rate is same,different particle dimension and different particle distribution can lead to difference in its effective conductivity.What's more, contact conductivity between particles makes the establishment and research of porous media conduct extremely demanding.Therefore,to reduce the error resulted from the hypothesis of complex construction in porous media,present research of efficient conductivity of porous media is carded through bisearch and Genetic Algorithm(GA).Effective conductivity is an important physical quantity describing heat conduction of porous media.Hence its correct determination is of crucial significance for people to understand the internal heat conduction in porous media.Firstly,the present research converts the practical heat conduction in porous media into equivalent heat conduction of common solid materials,and establishes a temperature model of heat conduction process in porous media.Besides,an experimental system is designed and temperature variation curve of different spots inside the sample under different furnace temperature is achieved.Secondly, porous media's effective conductivity-temperature variation curve is obtained through inversion operated on effective conductivity by virtue of bisearch.The research indicates that it is a rather effective method to inverse effective conductivity with bisearch.The research indicates that it is a rather effective method to inverse effective conductivity with bisearch, while the solution of biresearch is vulnerable to the influence of presupposed temperature field precision,and it is easy to fall into partial optimal solution.As to the problem caused by bisearch,the present paper establishes a model of effective conductivity in porous media by virtue of Genetic Algorithm(GA).Genetic Algorithm(GA) is a kind of random search algorithm drawing lesions from biological selection and natural genetic system.With coding of decision variable as operating object,target function as searching information,it searches information through many searching points and probability searching technology,and it has the characteristics of self-organization,self-adaptive and self-learning.Depending on the Genetic Algorithm model of effective conductivity in porous media,the effective conductivity-temperature variation curve of base sands and paraffin sand developed independently by the lab is obtained,and analysis to the curve is also operated.The findings indicate that:Genetic Algorithm is plausible in the solution of effective conductivity in porous media,and the application of this method avoids the analysis on the internal complicated structure of porous media,global solution with relatively high precision can be obtained.The solution to efficient conductivity in porous media through Genetic Algorithm(GA) and bisearch can avoid the analysis on internal complex construction of porous media,hence reduce the calculation error caused by internal structure analysis. Through comparative verification,it is plausible to solute efficient conductivity of porous media through Genetic Algorithm(GA) and bisearch.