Show simple item record

dc.contributor.advisorKamrin, Ken
dc.contributor.authorKim, Seongmin
dc.date.accessioned2021-11-22T18:04:29Z
dash.embargo.terms2022-05-16
dc.date.created2021
dc.date.issued2021-11-16
dc.date.submitted2021-11
dc.identifier.citationKim, Seongmin. 2021. Determining Nonlocal Granular Rheology from Discrete Element Simulations. Doctoral dissertation, Harvard University Graduate School of Arts and Sciences.
dc.identifier.other28768248
dc.identifier.urihttps://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37370215*
dc.description.abstractWe determine the constitutive equation of simple granular materials considering them as continuous fluids. Based on discrete element simulations, we propose two rheological models with different Rivlin-Ericksen tensor orders. In the first-order model, we identify that rescaling the shear-to-stress ratio $\mu$ by a power function of dimensionless granular temperature $\Theta$ makes the data from many different flow geometries collapse to a single curve which depends only on the inertial number $I$. The basic power-law structure appears robust to varying surface friction in both 2D and 3D systems. We also observe that $\phi$ is a function of $\mu$, which connects our rheology to kinetic theory and the nonlocal granular fluidity model. In order to describe stress anisotropy and secondary flows, we extend our model by including the second-order Rivlin Ericksen tensor. Using DEM data, we find the equations for three model parameters $\mu_1$, $\mu_2$, and $\mu_3$ as functions of $I$ and $\Theta$. We observe similar power-law scaling in $\mu_1$ and $\mu_2$ while $\mu_3$ distributes near zero for small $I$. The first and second normal stress differences $N_1$ and $N_2$ are also measured and discussed. We validate the models by running finite difference method simulations of inclined chute flows. We show that the second-order model predicts all the velocity components including secondary flows while the first-order model predicts velocity in the downstream direction only. Both models successfully predict the exponentially decaying velocity as $\Theta$ is included in the model parameters.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dash.licenseLAA
dc.subjectAmorphous Material
dc.subjectGranular Flow
dc.subjectGranular Material
dc.subjectGranular Rheology
dc.subjectNonlocal Rheology
dc.subjectSoft Matter
dc.subjectApplied physics
dc.subjectMechanical engineering
dc.subjectGeophysics
dc.titleDetermining Nonlocal Granular Rheology from Discrete Element Simulations
dc.typeThesis or Dissertation
dash.depositing.authorKim, Seongmin
dash.embargo.until2022-05-16
dc.date.available2021-11-22T18:04:29Z
thesis.degree.date2021
thesis.degree.grantorHarvard University Graduate School of Arts and Sciences
thesis.degree.levelDoctoral
thesis.degree.namePh.D.
dc.contributor.committeeMemberRycroft, Chris
dc.contributor.committeeMemberSpaepen, Frans
dc.type.materialtext
thesis.degree.departmentEngineering and Applied Sciences - Applied Physics
dc.identifier.orcid0000-0001-5766-7605
dash.author.emailseongminage@gmail.com


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record