Naslov
Wo-way coupled Eulerian-Eulerian finite volume simulation of drifting snow

Autori
Ziad, Boutanios

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Fakultet
Fakultet strojarstva i brodogradnje

Mjesto
Zagreb

Datum
28.09

Godina
2018

Stranica
140

Mentor
Jasak, Hrvoje

Ključne riječi
Eulerian-Eulerian ; drifting snow ; sediment transport ; saltation ; suspension ; two-way coupling ; turbulent drag ; particle-laden flow ; solid particle phase viscosity

Sažetak
An Eulerian-Eulerian two-way coupled model for simulating drifting snow, and solid particle-laden ows, is presented. Turbulent drag is used to account for particles turbulent dispersion. A new solid particle phase viscosity model is also developed from rst principles. The present transport model resolves the saltation layer, instead of modelling it with equilibrium formulations as in one-way coupled models. Implementation is done in foam-extend, a community-driven fork of OpenFOAM R . Validation in saltation is done against measurements from a controlled drifting snow experiment using real snow particles. The present model accurately predicts snow ux and air ow velocity in equilibrium and non-equilibrium regimes, when particle size polydispersity is considered. The model overestimates experimental measurements of turbulent kinetic energy, with concerns over the completeness of the measurements. Validation in suspension is done against measurements from a controlled sediment suspension experiment. The present model accurately predicts sediment concentration pro les, water velocity pro les, and sediment fall velocity. The present model is also shown to be superior to a one-way coupled convection-diffusion model based on an equilibrium formulation. Finally, a non-perforated boundary condition used to represent perforated bottoms is found to have a localized e ect for the present model, and unsuitable for one-way coupled models. Using wall functions in such situations is also discouraged since it would produce turbulence structures very di erent from what is observed on perforated bottoms. A resolved low Reynolds number approach is recommended instead. The present viscosity model predicts mixture viscosity accurately, and more physically than published mixture viscosity models. In the dense drifting snow regime, a volume fraction correction and multiplicative constant of 0.1 are suggested to improve the Kazhikov-Smagulov particle viscosity model, and a variable constant equal to the local phase density ratio for the Carrier-Cashwell particle viscosity model. Particle turbulent viscosity modelled with the Ct model is found negligible for drifting snow, and comparable to water turbulent viscosity for sediment, due to phase density ratio.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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