Using the lattice Boltzmann multiphase model,numerical simulations have been performed to understand the dynamics of droplet formation in a microfluidic cross-junction.The influence of capillary number,flow rate ratio...Using the lattice Boltzmann multiphase model,numerical simulations have been performed to understand the dynamics of droplet formation in a microfluidic cross-junction.The influence of capillary number,flow rate ratio,viscosity ratio,and viscosity of the continuous phase on droplet formation has been systematically studied over a wide range of capillary numbers.Two different regimes,namely the squeezinglike regime and the dripping regime,are clearly identified with the transition occurring at a critical capillary number Cacr.Generally,large flow rate ratio is expected to produce big droplets,while increasing capillary number will reduce droplet size.In the squeezing-like regime(Ca≤Cacr),droplet breakup process is dominated by the squeezing pressure and the viscous force;while in the dripping regime(Ca>Cacr),the viscous force is dominant and the droplet size becomes independent of the flow rate ratio as the capillary number increases.In addition,the droplet size weakly depends on the viscosity ratio in both regimes and decreases when the viscosity of the continuous phase increases.Finally,a scaling law is established to predict the droplet size.展开更多
Herein, we used theoretical and experimental methods to investigate the shear fracture strengths of carbon fiber/epoxy resin interfaces. The shear strengths of carbon fiber and epoxy resin were measured using the micr...Herein, we used theoretical and experimental methods to investigate the shear fracture strengths of carbon fiber/epoxy resin interfaces. The shear strengths of carbon fiber and epoxy resin were measured using the microdroplet test, whereas interaction and binding energies were estimated using?Ab initio?and molecular dynamics methods. However, binding energies did not impact the shear strength volumes determined by microdroplet tests,?i.e., bonds between functional groups of the carbon filer and the epoxy resin were difficult to break. On the other hand, the interaction energies calculated for epoxy monomers were in good agreement with experimental data. Moreover, we determined the relationship between the simulated interaction energy and the shear fracture strength volume obtained using the microdroplet test.展开更多
文摘Using the lattice Boltzmann multiphase model,numerical simulations have been performed to understand the dynamics of droplet formation in a microfluidic cross-junction.The influence of capillary number,flow rate ratio,viscosity ratio,and viscosity of the continuous phase on droplet formation has been systematically studied over a wide range of capillary numbers.Two different regimes,namely the squeezinglike regime and the dripping regime,are clearly identified with the transition occurring at a critical capillary number Cacr.Generally,large flow rate ratio is expected to produce big droplets,while increasing capillary number will reduce droplet size.In the squeezing-like regime(Ca≤Cacr),droplet breakup process is dominated by the squeezing pressure and the viscous force;while in the dripping regime(Ca>Cacr),the viscous force is dominant and the droplet size becomes independent of the flow rate ratio as the capillary number increases.In addition,the droplet size weakly depends on the viscosity ratio in both regimes and decreases when the viscosity of the continuous phase increases.Finally,a scaling law is established to predict the droplet size.
文摘Herein, we used theoretical and experimental methods to investigate the shear fracture strengths of carbon fiber/epoxy resin interfaces. The shear strengths of carbon fiber and epoxy resin were measured using the microdroplet test, whereas interaction and binding energies were estimated using?Ab initio?and molecular dynamics methods. However, binding energies did not impact the shear strength volumes determined by microdroplet tests,?i.e., bonds between functional groups of the carbon filer and the epoxy resin were difficult to break. On the other hand, the interaction energies calculated for epoxy monomers were in good agreement with experimental data. Moreover, we determined the relationship between the simulated interaction energy and the shear fracture strength volume obtained using the microdroplet test.
