In this study,the evaporation characteristics and drying patterns of various sessile ferrofluid droplets on certain substrate under horizontal magnetic fields of controlled intensities are reported.The effects of drop...In this study,the evaporation characteristics and drying patterns of various sessile ferrofluid droplets on certain substrate under horizontal magnetic fields of controlled intensities are reported.The effects of droplet concentration and magnetic field intensity on the duration of each evaporation stage and drying patterns of droplets have been systematically investigated.It turned out that a plateau appears at the initial stage of evaporation in the absence of magnetic field and it was found that the plateau value is positively correlated with the concentration of ferrofluid droplets.Under the external magnetic field,the evaporation time of droplets decreases,the stage of contact line retreat extends,the stage of late pinning mode shortens,and the deposition area of ferrofluid droplet decreases compared to that of without magnetics field.The deposition area increases gradually and becomes more uniform with the increase of magnetic field.The decrease of friction force which is due to the decrease of the number of nanoparticles at the contact line under external magnetic field is the main reason for the observed phenomena.We found that the coffee ring and the uniform deposition inside the droplet will be destroyed when the magnetic field intensity is higher than a critical value.Our work has a significant reference value for the evaporation of sessile magnetic fluid droplets under the applied magnetic field,especially when the drying pattern needs to be precisely controlled,such as in spray or biomedicine.展开更多
A new dry deposition velocity pattern (NDDVP) for the study of region-scale dry deposition processes is developed. The mean ratio between NDDVP and 1022 experimental data of dry deposi- tion velocity V_d is 1. 06±...A new dry deposition velocity pattern (NDDVP) for the study of region-scale dry deposition processes is developed. The mean ratio between NDDVP and 1022 experimental data of dry deposi- tion velocity V_d is 1. 06±0.82. The result shows that NDDVP is well consistent with experimental data. Practical cases are forecasted by the high resolution regional acid deposition model (EM3) with both NDDVP and old V_d pattern. The maximum ratio between the central concentrations for SO4 can reach 2.4 only due to different V_d patterns. 3-D distributions of species concentrations and dry depositions forecasted by NDDVP are better than those by the old V_d pattern.展开更多
基金The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China(Grants No.52025061 and 51961130386)Royal Society-Newton Advanced Fellowship(Grant No.NAF/R1/191163)This work was also supported by the China Fundamental Research Funds for the Central Universities.
文摘In this study,the evaporation characteristics and drying patterns of various sessile ferrofluid droplets on certain substrate under horizontal magnetic fields of controlled intensities are reported.The effects of droplet concentration and magnetic field intensity on the duration of each evaporation stage and drying patterns of droplets have been systematically investigated.It turned out that a plateau appears at the initial stage of evaporation in the absence of magnetic field and it was found that the plateau value is positively correlated with the concentration of ferrofluid droplets.Under the external magnetic field,the evaporation time of droplets decreases,the stage of contact line retreat extends,the stage of late pinning mode shortens,and the deposition area of ferrofluid droplet decreases compared to that of without magnetics field.The deposition area increases gradually and becomes more uniform with the increase of magnetic field.The decrease of friction force which is due to the decrease of the number of nanoparticles at the contact line under external magnetic field is the main reason for the observed phenomena.We found that the coffee ring and the uniform deposition inside the droplet will be destroyed when the magnetic field intensity is higher than a critical value.Our work has a significant reference value for the evaporation of sessile magnetic fluid droplets under the applied magnetic field,especially when the drying pattern needs to be precisely controlled,such as in spray or biomedicine.
基金The study is supported by the National Natural Science Foundation of China,LASG and LAPC in IAP, CAS
文摘A new dry deposition velocity pattern (NDDVP) for the study of region-scale dry deposition processes is developed. The mean ratio between NDDVP and 1022 experimental data of dry deposi- tion velocity V_d is 1. 06±0.82. The result shows that NDDVP is well consistent with experimental data. Practical cases are forecasted by the high resolution regional acid deposition model (EM3) with both NDDVP and old V_d pattern. The maximum ratio between the central concentrations for SO4 can reach 2.4 only due to different V_d patterns. 3-D distributions of species concentrations and dry depositions forecasted by NDDVP are better than those by the old V_d pattern.
