The computational crystallography is proposed. Its basic concept and research method are systematically introduced, with aluminum-based spinel (ABS) as an example, through (i) selecting basic crystal structural unit, ...The computational crystallography is proposed. Its basic concept and research method are systematically introduced, with aluminum-based spinel (ABS) as an example, through (i) selecting basic crystal structural unit, (ii) determining the mathematical expression of crystal structure, (iii) computing the stability energy of growth unit and finding out which is (are) favorable one(s), and (iv) describing the formation process of crystal morphology. The morphology of ABS deduced from the computation is in excellent agreement with that from hydrothermal experiments.展开更多
The closure problem of turbulence is still a challenging issue in turbulence modeling. In this work, a stability condition is used to close turbulence. Specifically, we regard single-phase flow as a mixture of turbule...The closure problem of turbulence is still a challenging issue in turbulence modeling. In this work, a stability condition is used to close turbulence. Specifically, we regard single-phase flow as a mixture of turbulent and non-turbulent fluids, separating the structure of turbulence. Subsequently, according to the picture of the turbulent eddy cascade, the energy contained in turbulent flow is decomposed into different parts and then quantified. A turbulence stability condition, similar to the principle of the energy-minimization multi-scale （EMMS） model for gas-solid systems, is formulated to close the dynamic constraint equa- tions of turbulence, allowing the inhomogeneous structural parameters of turbulence to be optimized. We name this model as the ＂EMMS-based turbulence model＂, and use it to construct the corresponding turbulent viscosity coefficient. To validate the EMMS-based turbulence model, it is used to simulate two classical benchmark problems, lid-driven cavity flow and turbulent flow with forced convection in an empty room, The numerical results show that the EMMS-hased turbulence model improves the accuracy of turbulence modeling due to it considers the principle of compromise in competition between viscosity and inertia.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.59832080).
文摘The computational crystallography is proposed. Its basic concept and research method are systematically introduced, with aluminum-based spinel (ABS) as an example, through (i) selecting basic crystal structural unit, (ii) determining the mathematical expression of crystal structure, (iii) computing the stability energy of growth unit and finding out which is (are) favorable one(s), and (iv) describing the formation process of crystal morphology. The morphology of ABS deduced from the computation is in excellent agreement with that from hydrothermal experiments.
基金supported by the National Natural Science Foundation of China(No.21106155)Science Foundation of the Chinese Academy of Sciences(No.XDA07080303)China Postdoctoral Science Foundation(No.2012M520385)
文摘The closure problem of turbulence is still a challenging issue in turbulence modeling. In this work, a stability condition is used to close turbulence. Specifically, we regard single-phase flow as a mixture of turbulent and non-turbulent fluids, separating the structure of turbulence. Subsequently, according to the picture of the turbulent eddy cascade, the energy contained in turbulent flow is decomposed into different parts and then quantified. A turbulence stability condition, similar to the principle of the energy-minimization multi-scale （EMMS） model for gas-solid systems, is formulated to close the dynamic constraint equa- tions of turbulence, allowing the inhomogeneous structural parameters of turbulence to be optimized. We name this model as the ＂EMMS-based turbulence model＂, and use it to construct the corresponding turbulent viscosity coefficient. To validate the EMMS-based turbulence model, it is used to simulate two classical benchmark problems, lid-driven cavity flow and turbulent flow with forced convection in an empty room, The numerical results show that the EMMS-hased turbulence model improves the accuracy of turbulence modeling due to it considers the principle of compromise in competition between viscosity and inertia.
