A Review of Computational Models for the Flow of Milled Biomass Part II: Continuum-Mechanics Models

Wencheng Jin, Jonathan Stickel, Yidong Xia, Jordan Klinger

Research output: Contribution to journalArticlepeer-review

20 Scopus Citations


The design of efficient material-handling systems for milled lignocellulosic biomass is challenging due to their complex particle morphologies and frictional interactions. Computational modeling, including the discrete element method (DEM) and continuum-based finite-element/volume methods, may offer scientific insight and predictive capabilities for the flow of milled biomass in hoppers and feeders. This article (Part II) presents a review of current state-of-the-art continuum models for the flow of milled biomass, whereas DEM models are reviewed in a companion article (Part I). Advances of numerical methods to solve the global governing equations are discussed first, followed by a comprehensive review of constitutive models for granular materials, including Drucker–Prager, hypoplastic, Cambridge-type, inertial-rheology, and nonlocal granular fluidity models. Specifically, we provide in-depth discussion on the suitability of those models for milled lignocellulosic biomass materials in terms of nonlinear elasticity, dependence of flow strength on pressure, density and shear rate, and compaction (dilation) associated with hardening (softening). Our study shows that, despite the recent advances in continuum granular flow modeling, the most suitable constitutive models still need further development to account for material parametrization, multiflow regimes, and multiscale behavior before they can be reliably used to optimize the design and operation of biomass handling systems.
Original languageAmerican English
Pages (from-to)6157-6172
Number of pages16
JournalACS Sustainable Chemistry and Engineering
Issue number16
StatePublished - 2020

NREL Publication Number

  • NREL/JA-2700-75992


  • bulk flow
  • dense regime
  • finite-element
  • finite-volume
  • granular materials
  • lignocellulose
  • quasi-static regime


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