Publications

Results 51–75 of 163
Skip to search filters

Letter: Modeling reactive shock waves in heterogeneous solids at the continuum level with stochastic differential equations

Physics of Fluids

Kittell, David E.; Yarrington, Cole Y.; Lechman, Jeremy B.; Baer, M.R.

A new paradigm is introduced for modeling reactive shock waves in heterogeneous solids at the continuum level. Inspired by the probability density function methods from turbulent reactive flows, it is hypothesized that the unreacted material microstructures lead to a distribution of heat release rates from chemical reaction. Fluctuations in heat release, rather than velocity, are coupled to the reactive Euler equations which are then solved via the Riemann problem. A numerically efficient, one-dimensional hydrocode is used to demonstrate this new approach, and simulation results of a representative impact calculation (inert flyer into explosive target) are discussed.

More Details
TYPE Journal Article YEAR 2018
ScopusOSTIDOI

Simulations of the effects of proppant placement on the conductivity and mechanical stability of hydraulic fractures

International Journal of Rock Mechanics and Mining Sciences

Bolintineanu, Dan S.; Rao, Rekha R.; Lechman, Jeremy B.; Romero, Joseph A.; Jove Colon, Carlos F.; Quintana, Enrico C.; Bauer, Stephen J.; Ingraham, Mathew D.

We generate a wide range of models of proppant-packed fractures using discrete element simulations, and measure fracture conductivity using finite element flow simulations. This allows for a controlled computational study of proppant structure and its relationship to fracture conductivity and stress in the proppant pack. For homogeneous multi-layered packings, we observe the expected increase in fracture conductivity with increasing fracture aperture, while the stress on the proppant pack remains nearly constant. This is consistent with the expected behavior in conventional proppant-packed fractures, but the present work offers a novel quantitative analysis with an explicit geometric representation of the proppant particles. In single-layered packings (i.e. proppant monolayers), there is a drastic increase in fracture conductivity as the proppant volume fraction decreases and open flow channels form. However, this also corresponds to a sharp increase in the mechanical stress on the proppant pack, as measured by the maximum normal stress relative to the side crushing strength of typical proppant particles. We also generate a variety of computational geometries that resemble highly heterogeneous proppant packings hypothesized to form during channel fracturing. In some cases, these heterogeneous packings show drastic improvements in conductivity with only moderate increase in the stress on the proppant particles, suggesting that in certain applications these structures are indeed optimal. We also compare our computer-generated structures to micro computed tomography imaging of a manually fractured laboratory-scale shale specimen, and find reasonable agreement in the geometric characteristics.

More Details
TYPE Journal Article YEAR 2017
ScopusOSTIDOI
Results 51–75 of 163
Results 51–75 of 163