The non-homogeneous flow of a thixotropic fluid around a sphere
- Kim, Jaekwang; Park, Jun Dong
- Issue Date
- ELSEVIER SCIENCE INC
- Thixotropy; Flow around a sphere; Structure-kinetics model; non-homogenous flow
- APPLIED MATHEMATICAL MODELLING, v.82, pp.848 - 866
- Journal Title
- APPLIED MATHEMATICAL MODELLING
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- End Page
- The non-homogeneous flow of a thixotropic fluid around a settling sphere is simulated. A four-parameter Moore model is used for a generic thixotropic fluid and discontinuous Galerkin method is employed to solve the structure-kinetics equation coupled with the conservation equations of mass and momentum. Depending on the normalized falling velocity U*, which compares the time scale of structure formation and destruction, flow solutions are divided into three different regimes, which are attributed to an interplay of three competing factors: Brownian structure recovery, shear-induced structure breakdown, and the convection of microstructures. At small U*( << 1), where the Brownian structure recovery is predominant, the thixotropic effect is negligible and flow solutions are not too dissimilar to that of a Newtonian fluid. As U* increases, a remarkable structural gradient is observed and the structure profile around the settling sphere is determined by the balance of all three competing factors. For large enough U*( >> 1), where the Brownian structure recovery becomes negligible, the balance between shear-induced structure breakdown and the convection plays a decisive role in determining flow profile. To quantify the interplay of three factors, the drag coefficient Cs of the sphere is investigated for ranges of U*. With this framework, the effect of the destruction parameter, the confinement ratio, and a possible nonlinearity in the model-form on the non-homogeneous flow of a thixotropy fluid have been addressed. (C) 2020 Elsevier Inc. All rights reserved.
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