The drag force on a cylindrical particle is calculated using lattice Boltzmann method. The results show that the drag coefficient of a particle with different orientation angles decreases with increasing Reynolds numb...The drag force on a cylindrical particle is calculated using lattice Boltzmann method. The results show that the drag coefficient of a particle with different orientation angles decreases with increasing Reynolds number. When the principal axis of the particle is parallel to flow, the drag coefficient is much larger than that of others and decreases fastest with increasing Reynolds number, which becomes more obvious with increasing particle aspect ratio. When the principal axis of the particle is inclined to flow, the drag coefficient is nearly the same for different particle aspect ratios. In the case of flow with small Reynolds number （Re〈 100）, the drag coefficient decreases with increasing orientation angle at different aspect ratios and Reynolds numbers. The drag coefficient is more sensitive to particle orientation angle when the particle orientation angle is small and the aspect ratio is large. Finally, a new correlation formula for the drag coefficient of cylindrical particle is established, with which the drag force on a cylindrical particle can be directly calculated based on the Reynolds number, particle aspect ratio and orientation angle.展开更多
We conducted measurements of black carbon （BC） aerosol in Jiaxing, China during autumn from September 26 to November 30, 2013. We investigated temporal and diurnal variations of BC, and its cor relations with meteor...We conducted measurements of black carbon （BC） aerosol in Jiaxing, China during autumn from September 26 to November 30, 2013. We investigated temporal and diurnal variations of BC, and its cor relations with meteorological parameters and other major pollutants. Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3, with an average of 5.1 μg/ms. The diurnal variation of BC exhibited a bimodal distribution, with peaks at 07：00 and 18：00. The morning peak was larger than the evening peak. The mass percentages of BC in PM2.s and PM10 were 7.1%and 4.8g, respectively. The absorption coefficient of BC was calculated to be 44.4 Mm-1, which accounted for 11.1% of the total aerosol extinction. BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11μg/m3 during the measurement period. Correlation analysis indicated that the main sources of BC were motor vehicle exhaust, and domestic and industrial combustion.展开更多
基金supported by the Scientific Project of Zhejiang Province (No.2008C01024-4)
文摘The drag force on a cylindrical particle is calculated using lattice Boltzmann method. The results show that the drag coefficient of a particle with different orientation angles decreases with increasing Reynolds number. When the principal axis of the particle is parallel to flow, the drag coefficient is much larger than that of others and decreases fastest with increasing Reynolds number, which becomes more obvious with increasing particle aspect ratio. When the principal axis of the particle is inclined to flow, the drag coefficient is nearly the same for different particle aspect ratios. In the case of flow with small Reynolds number （Re〈 100）, the drag coefficient decreases with increasing orientation angle at different aspect ratios and Reynolds numbers. The drag coefficient is more sensitive to particle orientation angle when the particle orientation angle is small and the aspect ratio is large. Finally, a new correlation formula for the drag coefficient of cylindrical particle is established, with which the drag force on a cylindrical particle can be directly calculated based on the Reynolds number, particle aspect ratio and orientation angle.
基金funded by the National Natural Science Foundation of China(Grant No.41305135)the Natural Science Foundation of Zhejiang Province(Grant No.LQ13D050001)the Chinese Academy of Sciences Strategic Priority Research Program (Grant No.XDB05020206)
文摘We conducted measurements of black carbon （BC） aerosol in Jiaxing, China during autumn from September 26 to November 30, 2013. We investigated temporal and diurnal variations of BC, and its cor relations with meteorological parameters and other major pollutants. Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3, with an average of 5.1 μg/ms. The diurnal variation of BC exhibited a bimodal distribution, with peaks at 07：00 and 18：00. The morning peak was larger than the evening peak. The mass percentages of BC in PM2.s and PM10 were 7.1%and 4.8g, respectively. The absorption coefficient of BC was calculated to be 44.4 Mm-1, which accounted for 11.1% of the total aerosol extinction. BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11μg/m3 during the measurement period. Correlation analysis indicated that the main sources of BC were motor vehicle exhaust, and domestic and industrial combustion.
