The water-inrush mechanism of strong water-guide collapse column in coal seam is studied based on the establishment of geological and mathematical models of "triangle" water-inrush mode. The geological backg...The water-inrush mechanism of strong water-guide collapse column in coal seam is studied based on the establishment of geological and mathematical models of "triangle" water-inrush mode. The geological background of Shuangliu mine is considered a prototype, similar simulation tests are adopted to analyze the water-inrush rules under this model, and the formation of water-guide channel and water-inrush process is investigated by examining the changes in rock resistivity. This work also uses the coupled cloud image derived from numerical simulation software to verify the results of simulation test. Results show that the numerical simulation of "triangle" water-inrush mode is consistent with the similar simulation. The "triangle" seepage area, which is located at the bottom of collapse columns and is connected to aquifer, is caused by the altered seepage direction and strengthened seepage actions after the overlapping of hydraulic transverse seepage in collapse column and hydraulic vertical seepage flow in aquifer. Under "triangle"water-inrush model, water-guide channel is formed by the communication between plastic failure zone of working face baseplate and"triangular" seepage area. Accordingly, the threatening water-inrush distance between working face and collapse column increases by 20 m compared with that of theoretical calculation.展开更多
The flow resistance of stent with different shapes of wire cross-section can be considered as a factor that influences the condition of inflow and outflow through the stent wire. Different from the traditional stents,...The flow resistance of stent with different shapes of wire cross-section can be considered as a factor that influences the condition of inflow and outflow through the stent wire. Different from the traditional stents, a novel stent with triangular wire cross-section was proposed, and numerical simulations were performed to compare the hemodynamic effect of the novel stent with that of traditional ones. Three constructed aneurysm models were treated with a different kin^l of stent separately, including one with bare circular wire cross-section stent （named CM）, one with bare rectangular wire cross-section stent （named RM）, one with bare triangular cross-section stent （named TM）. An unstented aneurysm model was also constructed to serve as a control （named UM）. Numerical simulations of the fluid-structure interaction in these four models were performed under the same boundary conditions using finite element method. The simulation results demonstrated the resistance of the novel stent is lower than RM stent, but higher than that of CM stent. TM stent attributes a higher velocity decreasing and a longer turnover time compared with CM stent. The distribution of wall shear stress indicated the possibility of aneurysm development along the distal wall was higher than the proximal wall, and the top of aneurysm was in the highest risk of rupture.展开更多
The dynamic behavior of the moving liquid column coalescing with a sessile droplet in triangular microchannels is numerically investigated by using coupled volume of fluid with level set interface tracking method impl...The dynamic behavior of the moving liquid column coalescing with a sessile droplet in triangular microchannels is numerically investigated by using coupled volume of fluid with level set interface tracking method implemented in ANSYS Fluent 14.5 in conjunction with the continuum surface force model. It is found that for both hydrophobic and hydrophilic microchannels, the coalescence between the moving liquid column and droplet can accelerate the original liquid column movement as a result of the induced curvature that lowers the liquid pressure at the interface. As compared to the rectangular microchannel with the same hydraulic diameter, the triangular microchannel exhibits smaller velocity increment ratio because of stronger viscous effect. Simulation results also reveal that the velocity increment ratio increases with the contact angle in hydrophobic microchannels, but it is reverse in the hydrophilic microchannels. The effects of the droplet size, lengthways and transverse positions are also investigated in this work. It is shown that larger droplet and smaller distance between the droplet and inlet or the substrate center can result in larger velocity increment ratio as a result of higher surface energy and lower viscous dissipation energy, respectively. The results obtained in this study create a solid theoretical foundation for designingand optimizing microfluidic devices encountering such a typical phenomenon.展开更多
基金Projects(51374093,51104058)supported by the National Natural Science Foundation of ChinaProject(2013CB227903)supported by the National Basic Research Program of China
文摘The water-inrush mechanism of strong water-guide collapse column in coal seam is studied based on the establishment of geological and mathematical models of "triangle" water-inrush mode. The geological background of Shuangliu mine is considered a prototype, similar simulation tests are adopted to analyze the water-inrush rules under this model, and the formation of water-guide channel and water-inrush process is investigated by examining the changes in rock resistivity. This work also uses the coupled cloud image derived from numerical simulation software to verify the results of simulation test. Results show that the numerical simulation of "triangle" water-inrush mode is consistent with the similar simulation. The "triangle" seepage area, which is located at the bottom of collapse columns and is connected to aquifer, is caused by the altered seepage direction and strengthened seepage actions after the overlapping of hydraulic transverse seepage in collapse column and hydraulic vertical seepage flow in aquifer. Under "triangle"water-inrush model, water-guide channel is formed by the communication between plastic failure zone of working face baseplate and"triangular" seepage area. Accordingly, the threatening water-inrush distance between working face and collapse column increases by 20 m compared with that of theoretical calculation.
文摘The flow resistance of stent with different shapes of wire cross-section can be considered as a factor that influences the condition of inflow and outflow through the stent wire. Different from the traditional stents, a novel stent with triangular wire cross-section was proposed, and numerical simulations were performed to compare the hemodynamic effect of the novel stent with that of traditional ones. Three constructed aneurysm models were treated with a different kin^l of stent separately, including one with bare circular wire cross-section stent （named CM）, one with bare rectangular wire cross-section stent （named RM）, one with bare triangular cross-section stent （named TM）. An unstented aneurysm model was also constructed to serve as a control （named UM）. Numerical simulations of the fluid-structure interaction in these four models were performed under the same boundary conditions using finite element method. The simulation results demonstrated the resistance of the novel stent is lower than RM stent, but higher than that of CM stent. TM stent attributes a higher velocity decreasing and a longer turnover time compared with CM stent. The distribution of wall shear stress indicated the possibility of aneurysm development along the distal wall was higher than the proximal wall, and the top of aneurysm was in the highest risk of rupture.
基金supported by the National Natural Science Foundation of China(5122260351276208 and51325602)+1 种基金the Fundamental Research Funds for the Central Universities(CDJZR12148801)Program for New Century Excellent Talents in University(NCET-12-0591)
文摘The dynamic behavior of the moving liquid column coalescing with a sessile droplet in triangular microchannels is numerically investigated by using coupled volume of fluid with level set interface tracking method implemented in ANSYS Fluent 14.5 in conjunction with the continuum surface force model. It is found that for both hydrophobic and hydrophilic microchannels, the coalescence between the moving liquid column and droplet can accelerate the original liquid column movement as a result of the induced curvature that lowers the liquid pressure at the interface. As compared to the rectangular microchannel with the same hydraulic diameter, the triangular microchannel exhibits smaller velocity increment ratio because of stronger viscous effect. Simulation results also reveal that the velocity increment ratio increases with the contact angle in hydrophobic microchannels, but it is reverse in the hydrophilic microchannels. The effects of the droplet size, lengthways and transverse positions are also investigated in this work. It is shown that larger droplet and smaller distance between the droplet and inlet or the substrate center can result in larger velocity increment ratio as a result of higher surface energy and lower viscous dissipation energy, respectively. The results obtained in this study create a solid theoretical foundation for designingand optimizing microfluidic devices encountering such a typical phenomenon.
