Download Eulerian Multiphase Granular.zip for CFD-Based Erosion Analysis

A modal discontinuous Galerkin method was developed for computing compressible rarefied gaseous flows interacting with rigid particles and granular medium. In contrast to previous particle-based models that were developed to handle rarefied flows or solid phase particles, the present computational method employs full continuum-based models. This work is one of the first attempts to apply the modal discontinuous Galerkin method to a two-fluid model framework, which covers a wide range of gas and solid phase regimes, from a continuum to non-equilibrium gas, and from dusty to collisional regimes. The rarefaction effects were taken into account by applying the second-order Boltzmann-Curtiss-based constitutive relationship in a two-fluid system of equations. For the dust phase, computational models were developed based on the kinetic theory of the granular flows. Due to the orthogonal property of the basis functions in the method, no specific treatment of the source terms, commonly necessary in the conventional finite volume method, was required. Moreover, a high-fidelity approach was selected to treat the non-strictly hyperbolic equations of a dusty gas. This allows the same inviscid numerical flux functions to be applied to both the gaseous Euler and solid pressureless-Euler system of equations. Further, we observed that, for the discretization of the viscous fluxes in multiphase cases, the local discontinuous Galerkin is superior to the first method by Bassi and Rebay. After a verification and validation study, the new computational model was used to simulate the impingement of an underexpanded jet on a dusty surface in a rarefied condition. A surface erosion model based on viscous erosion associated with aerodynamic entrainment was implemented at a solid surface. Simulation cases in the near-field of the nozzle flow were tested to evaluate the capabilities of the present computational model in handling the challenging problems of multi-scale multiphase flows.

Eulerian Multiphase Granular.zip

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The role of scientific research is vital in understandingthe key phenomena and processes involved in advanced technologies. Theenvironmental concerns require special consideration in all technologiesrelated to energy, chemical, manufacturing and similar industries. Gas-solidmultiphase flow systems are scientifically very challenging to study because ofcomplexities which make their modeling very hard to precisely and reliablypredict. A broad application of the gas-solid multiphase flows in fluidized bed(FB) technology used in boilers, gasifiers, plants for calcium looping incarbon capture and storage, and plants for chemical looping indicate that anyimprovement in scientific views into the processes associated with gas-solidsystems can substantially improve the related technology for betterperformance. In practical terms, it means a lower cost with lower negativeimpacts on environment. This project aims at developing a multiscale approachto treat the core factor in gas-solid multiphase systems, which is known as thedrag force between phases. More specifically, this project focuses on systemswhich contain solid phases with granular particles of large size ratios (over10). Some preliminary computational studies conducted by the principal investigator(PI) of project have shown the significant failure of existing continuumformulation in estimation of drag forces. This consequently leads toinefficient, inaccurate and unreliable Eulerian two-fluid model computersimulations of gas-solid systems such as in FB plants for various industrialapplications mentioned above. The multiscale approach in the project relies onboth experimental and computational methods in collaboration with a leadingphysicist in experimental granular matter from Duke University, and amathematician from New Jersey Institute of Technology. The collaborations areboth to study the two-dimensional systems. The three-dimensional systems willbe also studied experimentally and computationally in internal collaborationwithin Lappeenranta University of Technology. The PI and collaborating groupsare experts in related fields with distinguished scientific knowledge andskills. In addition to scientific and technological outcome of project, it willhave many indirect impacts on society as well by making positive economiceffects on above-mentioned industries as well as helping for reducing theemissions with damaging environmental effects. 2ff7e9595c