Examinando por Autor "Uriarte, Carlos"

Mostrando 1 - 5 de 5

Design of a system for controlling a levitating sphere in superfluid 3He at extremely low temperatures
(Springer Nature, 2021-10-08) Arrayás, Manuel; Trueba, José Luis; Uriarte, Carlos; Zmeev, Dmitry E.
We present a new mechanical probe to study the properties of superfluid 3He at microkelvin temperatures down to 100 μK. The setup consists of a set of coils for levitating a superconducting sphere and controlling its motion in a wide variety of regimes. In particular, the realisation of motion of a levitating body at a uniform velocity presents both an experimental challenge and a promising direction into the study of the edge states in topological superfluid 3He-B. We include the theoretical study of the device stability and simulations to illustrate the capabilities of the control system.
Evolution of Vortex Filaments and Reconnections in the Gross–Pitaevskii Equation and its Approximation by the Binormal Flow Equation
(Springer Nature, 2025-02-21) Arrayás, Manuel; Fontelos, Marco A.; González, María D. M; Uriarte, Carlos
The evolution of a vortex line following the binormal flow equation (i.e. with a velocity proportional to the local curvature in the direction of the binormal vector) has been postulated as an approximation for the evolution of vortex filaments in both the Euler system for inviscid incompressible fluids and the Gross–Pitaevskii equation in superfluids. We address the issue of whether this is a suitable approximation or not and its degree of validity by using rigorous mathematical methods and direct numerical simulations. More specifically, we show that as the vortex core thickness goes to zero, the vortex core moves (at leading order and for long periods of time) with a velocity proportional to its local curvature and the binormal vector to the curve. The main idea of our analysis lies in a reformulation of the Gross–Pitaevskii equation in terms of associated velocity and vorticity fields that resemble the Euler system written in terms of vorticity in its weak form. We also present full numerical simulations aimed to compare Gross–Pitaevskii and binormal flow in various physical situations of interest such as the periodic evolution of deformed vortex rings and the reconnection of vortex filaments.
Machine learning techniques in magnetic levitation problems
(Elsevier, 2022) Arrayás, Manuel; Trueba, José L.; Uriarte, Carlos
We present a method for calculating the stability region of a perfect diamagnet levitated in a magnetic field created by a circular current loop making use of the machine learning techniques. As an application we compute stability regions, points of stable equilibrium and stable oscillatory motions in two chip-based superconducting trap architectures used to levitate superconducting particles. Our procedure is an alternative to a full numerical scheme based on finite element methods which are expensive to implement for optimizing experimental parameters.
Phase field modelling of the detachment of bubbles from a solid substrate
(AIP Publishing, 2024-06-03) Uriarte, Carlos; Fontelos, Marco A.; Arrayás, Manuel
We develop and implement numerically a phase field model for the evolution and detachment of a gas bubble resting on a solid substrate and surrounded by a viscous liquid. The bubble has a static contact angle θ and will be subject to gravitational forces. We compute, as a function of the static contact angle, the critical Bond number over which bubbles detach from the substrate. Then, we perform similar studies for bubble resting on inclined substrates and bubbles under the action of an external flow. We provide approximate formulas for the critical Bond number under all these circumstances. Our method is also able to resolve the pinchoff of the bubble and the possible appareance of satellites.
Progress on Levitating a Sphere in Cryogenic Fluids
(Springer Nature, 2023-02-04) Arrayás, Manuel; Bettsworth, Francis; Haley, Richard P.; Schanen, Roch; Trueba, José Luis; Uriarte, Carlos; Zavjalov, Vladislav; Zmeev, Dmitry E.
We present the working prototype of a levitation system designed for investigation of flows in cryogenic helium fluids. The current device allows the levitation of a superconducting sphere and has several provisions made for allowing precise control over its motion. We report on progress in the detection and control systems of the prototype and demonstrate how uniform circular motion can be implemented.