3D3C velocimetry measurements of an electrothermal microvortex using wavefront deformation PTV and a single camera

We study the three-dimensional fluid transport in an electrothermal microvortex (EMV), by using wavefront deformation particle-tracking velocimetry (PTV) developed at Universität der Bundeswehr München. By using a cylindrical lens in conjunction with a microscope objective lens, systematic wavefront deformations in the particle images are created. The particles are observed by a single camera and appear as ellipses. The elliptical nature of the particle images encodes out-of-plane information regarding the particle’s position. This new technique is ideally suited for measuring transport in the EMV and provides full three-dimensional, time-resolved particle trajectories with Lagrangian velocity and acceleration. Measurements reveal the toroidal nature of the EMV and the experimentally obtained velocities are used to validate a simplistic model, which describes the interaction between the applied laser illumination and the microfluidic device. The model allows one to conduct numerical simulations of the complex fluid transport in the EMV.

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