Skip to Main Content
 

Global Search Box

 
 
 
 

ETD Abstract Container

Abstract Header

Characterization of Low Weber Number Post-Impact Drop-Spread Dynamics by a Damped Harmonic System Model

Gande, Sandeep K.

Abstract Details

2011, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
The post-impact spread, recoil, and shape oscillations of a droplet impinging on a dry horizontal substrate at low Weber numbers (We < ~ 30) are modeled as the behavior of a second- order damped harmonic system. Droplets of six different Newtonian liquids (acetic anhydride, 4:3 aqueous glycerin, ethylene glycol, glycerin, propylene glycol, and water) impinging on hydrophobic (Teflon) and hydrophilic (glass) substrates are considered. These liquids are selected so as to cover a wide range of viscosities and surface tension coefficients. Photographic images of the post-impact spread-recoil process obtained using a high-speed digital video camera (2000 frames per second) at different Weber numbers are analyzed. A MATLAB® based numerical tool was developed to obtain the temporal variations of droplet height and spread from the high-speed images. The results are presented in terms of the flatness factor (the ratio of liquid height to the droplet diameter prior to impact) and the spread factor (the ratio of liquid spread to the droplet diameter prior to impact). It is observed that the transient flatness and spread factor variations on a hydrophobic substrate at low Weber number resemble the damped harmonic response of a mass-spring-damper system. During the spread, recoil, and shape oscillations, the surface tension force acts as a spring and liquid viscosity provides the damping. Due to contact angle hysteresis, the frequency of oscillations for the transient flatness factor variation is slightly different from that for the spread factor variation. Semi-empirical correlations are developed for the oscillation frequency and the damping factor as a function of drop Weber and Reynolds numbers. The predictions of temporal variations of the flatness factor and the spread factor from these equations agree very well with experimental measurements on a hydrophobic substrate (Teflon). The drop spread behavior on a glass substrate, because of its hydrophilic nature, does not follow the response of a mass-spring-damper system with a linear spring; perhaps a non-linear spring stiffness might capture its spread dynamics.
Milind Jog, PhD (Committee Chair)
Raj Manglik, PhD (Committee Member)
David Thompson, PhD (Committee Member)
91 p.

Recommended Citations

Citations

  • Gande, S. K. (2011). Characterization of Low Weber Number Post-Impact Drop-Spread Dynamics by a Damped Harmonic System Model [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1313696024

    APA Style (7th edition)

  • Gande, Sandeep. Characterization of Low Weber Number Post-Impact Drop-Spread Dynamics by a Damped Harmonic System Model. 2011. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1313696024.

    MLA Style (8th edition)

  • Gande, Sandeep. "Characterization of Low Weber Number Post-Impact Drop-Spread Dynamics by a Damped Harmonic System Model." Master's thesis, University of Cincinnati, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1313696024

    Chicago Manual of Style (17th edition)