Authors: S. aus der Wiesche, C. Rembe, C. Maier and E.P. Hofer
Affilation: University of Ulm, Germany
Pages: 510 - 513
Keywords: microfluidic systems, microheaters, boiling nucleation, bubble dynamics
The physics of nucleation, boiling, bubble growth and collapse in thermal microactuators will be presented. The boiling process exhibits an equivalence to a phase transition of second order and this leads, in contrast to classical nucleation theory, to spatial extended nuclei. The dynamics of the resulting bubbles which grow from such extended nuclei is quite different from the dynamics of common vapor bubbles. However, a simple nucleation criterion can be given. The mathematical modeling and simulation of thermal microactuators is studied. The finite-volume-method is used to solve the coupled constitutive equations, i.e. the electrical potential equation for the heater, the nonlinear heat diffusion equation, and the three dimensional Navier-Stokes equation. Due to a hydrodynamic instability, the resulting bubble flow is found to be appreciable different from the corresponding perfect potential flow. The theoretical results agree well with experimental facts.
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