From the viewpoint of interaction mechanics for solid and gas, a coupled mathematical model was presented for solid coal/rock deformation and gas leak flow in parallel deformable coal seams. Numerical solutions using ...From the viewpoint of interaction mechanics for solid and gas, a coupled mathematical model was presented for solid coal/rock deformation and gas leak flow in parallel deformable coal seams. Numerical solutions using the SIP (Strong Implicit Proce- dure) method to the coupled mathematical model for double parallel coal seams were also developed in detail. Numerical simulations for the prediction of the safety range using protection layer mining were performed with experimental data from a mine with potential danger of coal/gas outbursts. Analyses show that the numerical simulation results are consistent with the measured data in situ.展开更多
Coal and gas outburst is one of the most serious natural calamities in collieries. And protective layer mining is an effective regional method for preventing and controlling coal outburst. However, how to rationally d...Coal and gas outburst is one of the most serious natural calamities in collieries. And protective layer mining is an effective regional method for preventing and controlling coal outburst. However, how to rationally determine the mining safety range in coal mining of protective layer with quantitative analysis is a difficult problem in rock mechanics and mining engineering so far. Then in this paper applied solid gas interaction mechanics for gas leakage flow, the solid gas interaction analysis for the safety range of up protective layer mining has been achieved with the results of experimental research and in situ measurements so that the result of numerical simulation for the difficult problem is closer to reality. Furthermore, the safety range of up protective layer mining can be determined with time dependent based on the result of numerical simulation.展开更多
A computational framework for parachute inflation is developed based on the immersed boundary/finite element approach within the open-source IBAMR library.The fluid motion is solved by Peskin's diffuse-interface i...A computational framework for parachute inflation is developed based on the immersed boundary/finite element approach within the open-source IBAMR library.The fluid motion is solved by Peskin's diffuse-interface immersed boundary(IB)method,which is attractive for simulating moving-boundary flows with large deformations.The adaptive mesh refinement technique is employed to reduce the computational cost while retain the desired resolution.The dynamic response of the parachute is solved with the finite element approach.The canopy and cables of the parachute system are modeled with the hyperelastic material.A tether force is introduced to impose rigidity constraints for the parachute system.The accuracy and reliability of the present framework is validated by simulating inflation of a constrained square plate.Application of the present framework on several canonical cases further demonstrates its versatility for simulation of parachute inflation.展开更多
The data information transfer and time marching strategies between computational fluid dynamics （CFD） and computational structural dynamics （CSD） play crucial roles on the aeroelastic analysis in a time domain. An...The data information transfer and time marching strategies between computational fluid dynamics （CFD） and computational structural dynamics （CSD） play crucial roles on the aeroelastic analysis in a time domain. An improved CFD/CSD coupled system is designed, including an interpolation method and an improved loosely coupled algorithm. The interpolation method based on boundary element method （BEM） is developed to transfer aerodynamic loads and structural displacements between CFD and CSD grid systems, it can be universally used in fluid structural interaction solution by keeping energy conservation. The improved loosely coupled algo-rithm is designed, thus it improves the computational accuracy and efficiency. The new interface is performed on the two-dimensional （2-D） extrapolation and the aeroelastie response of AGARD445.6 wing. Results show that the improved interface has a superior accuracy.展开更多
Carbon(C)and nitrogen(N)coupling processes in terrestrial ecosystems have the potential to modify the sensitivity of the global C cycle to climate change.But the degree to which C–N interactions contribute to the seq...Carbon(C)and nitrogen(N)coupling processes in terrestrial ecosystems have the potential to modify the sensitivity of the global C cycle to climate change.But the degree to which C–N interactions contribute to the sequestration of terrestrial ecosystem C(C_(seq)),both now and in the future,remains uncertain.In this study,we used a meta-analysis to quantitatively synthesize C and N responses from feld experiments on grasslands subjected to simulated warming and assessed the relative importance of three properties(changes in ecosystem N amount,redistribution of N among soil,litter and vegetation,and modifcations in the C:N ratio)associated with grassland C_(seq) in response to warming.Warming increased soil,litter and vegetation C:N ratios and approximately 2%of N shifted from the soil to vegetation and litter.Warming-induced grassland C_(seq) was the result of the net balance between increases in vegetation and litter C(111.2 g·m^(−2))and decreases in soil C(30.0 g·m^(−2)).Warming-induced accumulation of C stocks in grassland ecosystems indicated that the three processes examined were the main contributors to C_(seq),with the changes in C:N ratios in soil,litter and vegetation as the major contributors,followed by N redistribution,whilst a decrease in total N had a negative effect on C_(seq).These results indicate that elevated temperatures have a signifcant infuence on grassland C and N stocks and their coupling processes,suggesting that ecological models need to include C–N interactions for more accurate predictions of future terrestrial C storage.展开更多
文摘From the viewpoint of interaction mechanics for solid and gas, a coupled mathematical model was presented for solid coal/rock deformation and gas leak flow in parallel deformable coal seams. Numerical solutions using the SIP (Strong Implicit Proce- dure) method to the coupled mathematical model for double parallel coal seams were also developed in detail. Numerical simulations for the prediction of the safety range using protection layer mining were performed with experimental data from a mine with potential danger of coal/gas outbursts. Analyses show that the numerical simulation results are consistent with the measured data in situ.
文摘Coal and gas outburst is one of the most serious natural calamities in collieries. And protective layer mining is an effective regional method for preventing and controlling coal outburst. However, how to rationally determine the mining safety range in coal mining of protective layer with quantitative analysis is a difficult problem in rock mechanics and mining engineering so far. Then in this paper applied solid gas interaction mechanics for gas leakage flow, the solid gas interaction analysis for the safety range of up protective layer mining has been achieved with the results of experimental research and in situ measurements so that the result of numerical simulation for the difficult problem is closer to reality. Furthermore, the safety range of up protective layer mining can be determined with time dependent based on the result of numerical simulation.
基金supported by the Open Project of Key Laboratory of Aerospace EDLA,CASC(No.EDL19092208)。
文摘A computational framework for parachute inflation is developed based on the immersed boundary/finite element approach within the open-source IBAMR library.The fluid motion is solved by Peskin's diffuse-interface immersed boundary(IB)method,which is attractive for simulating moving-boundary flows with large deformations.The adaptive mesh refinement technique is employed to reduce the computational cost while retain the desired resolution.The dynamic response of the parachute is solved with the finite element approach.The canopy and cables of the parachute system are modeled with the hyperelastic material.A tether force is introduced to impose rigidity constraints for the parachute system.The accuracy and reliability of the present framework is validated by simulating inflation of a constrained square plate.Application of the present framework on several canonical cases further demonstrates its versatility for simulation of parachute inflation.
基金Supported by the Ph.D.Program Foundation of Ministry of Education of China (20070699054)~~
文摘The data information transfer and time marching strategies between computational fluid dynamics （CFD） and computational structural dynamics （CSD） play crucial roles on the aeroelastic analysis in a time domain. An improved CFD/CSD coupled system is designed, including an interpolation method and an improved loosely coupled algorithm. The interpolation method based on boundary element method （BEM） is developed to transfer aerodynamic loads and structural displacements between CFD and CSD grid systems, it can be universally used in fluid structural interaction solution by keeping energy conservation. The improved loosely coupled algo-rithm is designed, thus it improves the computational accuracy and efficiency. The new interface is performed on the two-dimensional （2-D） extrapolation and the aeroelastie response of AGARD445.6 wing. Results show that the improved interface has a superior accuracy.
基金supported by the Excellent Youth Scholars Program and the Special Project on Hi-Tech Innovation Capacity(KJCX20210416)from Beijing Academy of Agriculture and Forestry Sciences(BAAFS)the National Key Research and Development Program of China(2017YFA0604604).
文摘Carbon(C)and nitrogen(N)coupling processes in terrestrial ecosystems have the potential to modify the sensitivity of the global C cycle to climate change.But the degree to which C–N interactions contribute to the sequestration of terrestrial ecosystem C(C_(seq)),both now and in the future,remains uncertain.In this study,we used a meta-analysis to quantitatively synthesize C and N responses from feld experiments on grasslands subjected to simulated warming and assessed the relative importance of three properties(changes in ecosystem N amount,redistribution of N among soil,litter and vegetation,and modifcations in the C:N ratio)associated with grassland C_(seq) in response to warming.Warming increased soil,litter and vegetation C:N ratios and approximately 2%of N shifted from the soil to vegetation and litter.Warming-induced grassland C_(seq) was the result of the net balance between increases in vegetation and litter C(111.2 g·m^(−2))and decreases in soil C(30.0 g·m^(−2)).Warming-induced accumulation of C stocks in grassland ecosystems indicated that the three processes examined were the main contributors to C_(seq),with the changes in C:N ratios in soil,litter and vegetation as the major contributors,followed by N redistribution,whilst a decrease in total N had a negative effect on C_(seq).These results indicate that elevated temperatures have a signifcant infuence on grassland C and N stocks and their coupling processes,suggesting that ecological models need to include C–N interactions for more accurate predictions of future terrestrial C storage.
