Tortuosity is one of the key parameters to characterize the transport properties of porous media. There are many models for tortuosity estimation based on some definitions： geometric, hydraulic, electric, and diffusi...Tortuosity is one of the key parameters to characterize the transport properties of porous media. There are many models for tortuosity estimation based on some definitions： geometric, hydraulic, electric, and diffusive definitions, However, relationships among those tortuosities remain unclear due to the lack of di- rect comparison on the same porous media. Here we focus on hydraulic and electric tortuosities and have conducted a series of finite element simulations with the Navier-Stokes equation and the equation for electric current to directly compare tortuosities. The results revealed that： （1） on average, hydraulic tortu- osity is 15% greater than that of the electric one; （2） the proposed model based on the van Genuchten-type function successfully approximates both hydraulic and electric tortuosities; （3） tortuosities obtained from the nnrnus media hacked with circular narticles and square particles show quantitatively similar trends.展开更多
The deformation of reeds in automotive hydraulic shock absorbers is analyzed with the finite element method. Combination of different thick reeds mounted on different supports is studied. The computational results sho...The deformation of reeds in automotive hydraulic shock absorbers is analyzed with the finite element method. Combination of different thick reeds mounted on different supports is studied. The computational results show that deformation of the overlapped reeds is not always equal to the sum of deflection of single reed under any conditions. Experimental results prove computational results to be correct and computational method effective. The method of analysis and view of point can provide reference to the design and manufacture of hydraulic shock absorbers using reeds.展开更多
Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build ...Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element （FE） analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed orocedure to exolain the nile refusal phenomenon.展开更多
文摘Tortuosity is one of the key parameters to characterize the transport properties of porous media. There are many models for tortuosity estimation based on some definitions： geometric, hydraulic, electric, and diffusive definitions, However, relationships among those tortuosities remain unclear due to the lack of di- rect comparison on the same porous media. Here we focus on hydraulic and electric tortuosities and have conducted a series of finite element simulations with the Navier-Stokes equation and the equation for electric current to directly compare tortuosities. The results revealed that： （1） on average, hydraulic tortu- osity is 15% greater than that of the electric one; （2） the proposed model based on the van Genuchten-type function successfully approximates both hydraulic and electric tortuosities; （3） tortuosities obtained from the nnrnus media hacked with circular narticles and square particles show quantitatively similar trends.
基金This project is supported by Provincial Natural Science Foundation of Liaoning (972028) .Manuscript received on September 16, 19
文摘The deformation of reeds in automotive hydraulic shock absorbers is analyzed with the finite element method. Combination of different thick reeds mounted on different supports is studied. The computational results show that deformation of the overlapped reeds is not always equal to the sum of deflection of single reed under any conditions. Experimental results prove computational results to be correct and computational method effective. The method of analysis and view of point can provide reference to the design and manufacture of hydraulic shock absorbers using reeds.
基金supported by the National Natural Science Foundation of China(51322904 and 51279127)the Program for New Century Excellent Talents in University(HCET-11-0370)
文摘Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element （FE） analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed orocedure to exolain the nile refusal phenomenon.
