Experimental study on the electrohydrodynamic deformation of droplets in a combined DC electric field and shear flow field

A visualization experiment was conducted to investigate the electrohydrodynamic deformation of droplets in a combined DC electric field and shear flow field. Detailed experimental data on both the transient and steady droplet deformation parameters (D) and orientations (phi(d)) are provided at R > S and R < S (R: conductivity ratio; S: permittivity ratio) under different electric field and shear flow field combinations. The internal flow characteristics of the deformed droplet were also examined via the digital particle image velocimetry (DPIV) method. Due to the competition of the extensional component (EC) and the rotational component (RC) of these two fields on the droplet, the response of.. d is faster than that of D when an electric field is combined with a shear flow. Additionally, under the competition of the EC and RC at R > S and R < S, the steady-state D and phi(d) values exhibit distinct variations. In particular, surface charge convection plays a non-negligible role in enhancing and reducing droplet deformation at R > S and R < S, respectively. In addition, an asymmetric vortex forms inside the deformed droplet in the combined fields, and its velocity is lower under R > S and higher under R < S than in pure shear flow. The available prediction models use the experimental data to predict D, and a modified prediction model is proposed for improving the prediction accuracy of..phi(d)

Automated summary

The electrohydrodynamic deformation of droplets in a combined DC electric field and shear flow field was investigated through a visualization experiment. Detailed experimental data on both the transient and steady droplet deformation parameters and orientations were provided under different electric field and shear flow field combinations. The internal flow characteristics of the deformed droplet were also examined. The experimental results showed that the response of the droplet is faster than its deformation parameter when an electric field is combined with a shear flow. Additionally, an asymmetric vortex forms inside the deformed droplet in the combined fields.