Numerical Investigations of Macroscopic Particle Dynamics in Microflows

Sune Lomholt

    Research output: Book/ReportPh.D. thesis

    63 Downloads (Pure)


    During the last decade microflows has become an important scientific field with applications in the area of chemical, biological, and biomedical analyses. The increasing interest in using microflows for sorting and analysing cells or articles has resulted in the need of methods for computing the transport dynamics of these objects. In particulate microflows two main problems arise. Firstly, the size of the particles are only one or two orders of magnitude smaller than the smallest length scale of the carrying flow. Secondly, in many microsystems a considerably amount of particles are present (leading to a high volume fraction). So far no equation of motion for a particle in a fluid flow has been able to overcome these two problems. Consequently, another approach is needed for computing the particle dynamics in fluidic microsystems. A method called force coupling is introduced and developed. The method is not limited to small particles or to few particles (low volume fraction). It uses knowledge about the forces from the particles on the fluid flow to solve the equations of motion for the fluid. The motion of each of the particles are determined from the fluid velocity field as a volume average of the fluid velocity in the neighbourhood of each of the particles. The results from the force coupling method are verified by comparing with experimental data for a single sphere, two spheres, and three spheres rising in an inclined or vertical channel. Comparision of the trajectories and particle velocities show good agreement. Special attention is also given to the pressure driven Poiseuille flow, since microflows a typically of this kind. The force coupling method allows one to examine the disturbance flow created by the moving particles, and this can be used in the process of designing microfluidic structures for sorting, separating, or analysing particles or cells.
    Original languageEnglish
    Place of PublicationRoskilde
    PublisherRisø National Laboratory
    Number of pages139
    ISBN (Electronic)87-550-2584-6
    Publication statusPublished - 2001
    SeriesDenmark. Forskningscenter Risoe. Risoe-R


    • Risø-R-1215
    • Risø-R-1215(EN)

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