Microstructure Analysis And Laminar Drag Prediction Of Elemental Fluids Based On Energy Density

Tunnel and underground engineering field involving large amounts of fluid motion,such as groundwater seepage,the grouting engineering rock and soil mass flow slurry,pollutant migration,water seepage erosion,etc.,different fluid has the characteristics of different flow patterns,different viscous resistance in the process of performance for sports,now many indoor test method is adopted to improve the rheological test,a rheological model is then built,There is a lack of theoretical prediction methods for viscous resistance.However,rheological parameters of fluid vary greatly due to different components and it is difficult to sample and test.Therefore,it is urgent to establish a prediction method for fluid resistance to provide theoretical support for related researches on fluid motion.In order to reveal the intermolecular interaction on the influence of the fluid flow resistance mechanism,this article is based on the energy density of the fluid laminar motion state was studied by means of energy conversion,in a linear viscous fluid(small molecule Newtonian fluid)and nonlinear viscous fluid(carlo polymer fluid)as the research object,analyzes the fluid laminar flow resistance and quantitative relations of mutual acting force between the molecules,The prediction formula and constitutive equation of laminar flow resistance considering microcosmic action were established to provide a theoretical basis for the subsequent study of rheological properties of grout at molecular level.(1)Based on the energy density,the energy transformation process and internal causes of fluid laminar movement are revealed from macroscopic and microscopic levels.Based on differential element analysis method of moving fluid,the relationship between shear stress and work density of external force is studied,and the transformation process of work density of external force is clarified.On this basis,the viscous friction effect was considered to analyze the internal energy transformation path of fluid,and the concept of energy density was introduced to reveal the energy transformation process and internal reasons of fluid laminar movement from the macroscopic and microscopic perspectives,providing theoretical basis for the construction of steady laminar molecular movement model in the next step.(2)A steady laminar molecular motion model was established for small Newtonian fluid and the relationship between molecular interaction and fluid shear stress was established.Based on molecular state reunion with steady laminar microstructure characteristics,microscopic structure of molecular clusters of fluid coarse graining processing and layer structure processing,the steady laminar small molecule Newtonian fluid when the state of molecular motion,steady laminar molecular motion model is established,and reveals the van der Waals force and hydrogen bond interaction between molecules and the corresponding relation of shear stress,It provides theoretical basis for further research on laminar resistance prediction formula.(3)For linear viscous fluid(small molecule Newtonian fluid)and nonlinear viscous fluid(macromolecule Carreau fluid),the prediction formula and constitutive equation of laminar flow resistance considering microscopic effect are established.Based on the molecular well theory and the relationship between velocity gradient and shear rate,the prediction formula and constitutive equation of laminar flow resistance were established.For linear viscous fluids,small molecular alkanes,alcohols and water are studied.For nonlinear viscous fluid,the accuracy of prediction results of the new model was compared by temperature and shear rate with polydimethylsiloxane as the research object.The reliability of laminar flow resistance prediction model considering microcosmic effects is verified by comparing theoretical and experimental studies.