Roberto Zenit

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We conduct experiments with flexible swimmers to address the impact of fluid viscoelasticity on their locomotion. The swimmers are composed of a magnetic head actuated in rotation by a frequency-controlled magnetic field and a flexible tail whose deformation leads to forward propulsion. We consider both viscous Newtonian and glucose-based Boger fluids with(More)
The motion of a two-dimensional vortex pair moving toward a wall is studied numerically. The case for which the wall is heated is analyzed. The equations of momentum and energy conservation are solved using a finite volume scheme. In this manner, the instantaneous heat transfer from the wall is obtained and is related to the dynamics of the fluid vortex(More)
A novel device to produce a rotating magnetic field was designed, constructed, and tested. The system consists of a Helmholtz coil pair which is mechanically coupled to a dc electric motor whose angular velocity is controlled. The coil pair generates a uniform magnetic field; the whole system is rotated maintaining the coils energized using brushes. The(More)
A comparative experimental study of the velocity field and the strain field produced down-stream of biological and mechanical artificial valves is presented. In order to determine the spatial and temporal distributions of these fields, a phase-locked stereoscopic particle image velocimetry (or 3D-PIV) technique was implemented. Emphasis was placed on the(More)
Phys. Fluids 23, 107102 (2011) Particle accumulation on periodic orbits by repeated free surface collisions Phys. Fluids 23, 072106 (2011) Drag force of a particle moving axisymmetrically in open or closed cavities J. Chem. Phys. 135, 014904 (2011) Modal and non-modal stability of particle-laden channel flow Phys. Fluids 23, 064110 (2011) The suspension(More)
A numerical investigation of the collapse of granular columns has been conducted. In particular, we address the effect of the grain shape on the properties of the collapse. We show that the final runout and height of the deposits scale as a power law of the initial aspect ratio of the column, a, independently of the elongation of the grains used. We(More)
In a recent study the collisional particle pressure was measured for liquid fluidized beds and liquid-solid flows. The particle pressure was defined as the 'additional pressure' generated by the presence of the particulate-solid phase in a liquid-solid mixture. The particle pressure generated by collisions of particles was found to be composed of two main(More)
Painters often acquire a deep empirical knowledge of the way in which paints and inks behave. Through experimentation and practice, they can control the way in which fluids move and deform to create textures and images. David Alfaro Siqueiros, a recognized Mexican muralist, invented an accidental painting technique to create new and unexpected textures. By(More)