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Aerodynamics of Particle Detachment from Surfaces: A Numerical Study

Palakurthi, Nithin Kumar
http://orcid.org/0000-0002-6754-9044
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867161850956

Abstract Details

2017, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Understanding particle detachment from surfaces is necessary to better characterize dust generation and entrainment in large scale industries (such as metallurgical and foundry facilities, or in clean room settings, semiconductor device fabrication) and in health care, such as the desired inhalation of pharmaceuticals or the unwanted respiratory exposure to small particles (e.g. asbestos). The present work explores aerodynamics of a particle resting on a flat and non-flat surface subjected to fluid flows. Since many of the difficulties and results of the full 3D problem are manifest in the two-dimensions (2D), as a first step (2D) simulations are conducted in a parallel plate channel, where we approximate the particle as a cylinder. Next, in three-dimensions (3D), particle is represented as a sphere in a parallel plate channel. In both 2D and 3D cases, to model the particle just touching the surface leads to singularity in grid generation; we have addressed this issue with two concurrent approaches. In the first approach, the particle is located at various finite distances from the surface; results are then extrapolated to zero height (particle just touching the surface). In the second approach, the bottom of the particle is embedded into the surface at different depths; again, results are extrapolated to zero embedding depth. To study aerodynamics of the particle on a non-flat surface (Wedge and Cone), test particle is positioned at various axial (2D & 3D) and azimuthal (3D) locations on the wedge/cone. The cylinder diameter, wedge height and angles are varied to understand their effect on lift, drag and moment experienced by the test cylinder. Flow is assumed to be steady, laminar and incompressible. Simulations are carried out for a range of Reynolds numbers 1 < Re < 2000. A fully-developed velocity profile is specified at inlet of the domain. The computational domain is discretized using structured and hybrid grids taking into account the boundary layer physics. Incompressible Navier-Stokes equations are solved using finite-volume numerical code FLUENT. From the obtained numerical results, aerodynamic forces and moment for the test particle are computed and compared with results published in the literature. For the particle touching the surface, aerodynamic forces (drag and lift) and moments are obtained by extrapolation within both approaches (particle situated at finite height and the partially embedded particle). The results of the 2D and 3D simulations show that for a particle touching the surface, a threshold velocity (threshold Re) exists for particle detachment (i.e. positive lift) and moment plot indicates that the particle will tend to roll as it detaches. The results of the particle on a cone/wedge clearly indicate large variations in the lift and drag forces experienced by the particle on the sand pile. It is observed that forces are highest in magnitude on the test cylinder/sphere when it’s located upstream, near top of the wedge/cone. These forces and moment are insensitive to wedge angle, and increase with increase in wedge height. Drag doesn’t not vary significantly, whereas lift increases with decrease in particle size on wedge.
David Thompson, Ph.D. (Committee Chair)
Urmila Ghia, Ph.D. (Committee Member)
Kirti Ghia, Ph.D. (Committee Member)
Leonid Turkevich, Ph.D. (Committee Member)
78 p.
Aerospace Engineering; Mechanical Engineering
CFD; Lift; Drag; Particle Detachment; Singularity; Laminar

Recommended Citations

Citations

  • Palakurthi, N. K. (2017). Aerodynamics of Particle Detachment from Surfaces: A Numerical Study [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867161850956

    APA Style (7th edition)

  • Palakurthi, Nithin Kumar. Aerodynamics of Particle Detachment from Surfaces: A Numerical Study. 2017. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867161850956.

    MLA Style (8th edition)

  • Palakurthi, Nithin Kumar. "Aerodynamics of Particle Detachment from Surfaces: A Numerical Study." Master's thesis, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867161850956

    Chicago Manual of Style (17th edition)

ucin1511867161850956
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This open access ETD is published by University of Cincinnati and OhioLINK.