Simulation and Modeling of Microparticle Manipulation Using Standing Surface Acoustic waves

  • Fatima Ali Alshehhi

Student thesis: Master's Thesis

Abstract

Simulating particles behavior in microchannel considered to be an important and useful in many microfluidic applications that researchers try to understand, e.g. separation of cancer cells from blood. A dynamic behavior of polystyrene particle in water is described in this research. Theoretical analysis of forces acting on particles is conducted. Two different models are developed. The first model is based on Newton's equation of motion. The governing equations are solved using fourth order of Runga-Kutta method. The second model is based on immersed boundary-lattice Boltzmann method and the particle is under the effect of acoustic radiation force. Mapping parameters from the physical domain to the LBM domain is required to visualize the physical phenomena. Thus, A conversion factor is calculated by equalizing the ratios of acoustic radiation force to inertial force in both domains. The particles assumed to be at rest at the inlet of the channel. Standing surface acoustic waves are applied to align a microparticle with the centerline of a microchannel or focus them on the sides depending on the pressure node place. The effect of added mass force, Basset force, sedimentation force and Brownian motion compared to acoustic radiation force is very small and neglected for this case. The trajectory of a microparticle includes transient and steady state stages. Both models investigated for a microparticle entered the channel from different positions and for microparticles with different sizes, compressibility, and density. The larger particle moves a larger distance vertically due to the acoustic force differences. Also, the denser particle moves towards the pressure nodes faster due to the same previous reason. In addition, an experiment is conducted to focus the microparticle on sides and use it to validate the code. In this paper, Polystyrene, Iron oxide, Poly(methyl methacrylate), and other microparticles with a radius of 3 µm, 5 µm, 7 µm, and 9 µm are used.
Date of AwardApr 2022
Original languageAmerican English

Keywords

  • Microfluidics
  • Lattice Boltzmann
  • immersed boundary
  • Acoustophoresis
  • microparticle.

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