Applications to Monotone Semi-Lagrangian Schemes in Convective Cloud Simulations
| Autor: | Wang, Jing-Ying, 王旌熒 |
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| Rok vydání: | 1998 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 86 Semi-Lagrangian advection can use longer time step without affecting stability. Thus, it is more efficient and accurate than Euler scheme. As we use semi-Lagrangian schemes, we need to use interpolations to retrieve the value of next time step. But these interpolations often result in overshoot or undershoot, especially at vicinity of strong gradients or discontinuities. If this happened to water vapor, water vapor might be supersaturation or negative. Thus make the difficulties for parameterizations of microphysical processes. Many researches had been proposed to solve this problem, one of these strategies is monotone scheme, or called shape-preserving scheme. The monotone schemes described in this paper are QMSL (quasi-monotone semi-Lagrangian), LCSL (linear constrain semi-Lagrangian) and fifth interpolation polynomial. QMSL utilized the combination of high-order and low-order interpolations to construct a monotone scheme. LCSL utilized the immediate surrounding grid points of departure point to be the judge of whether to apply linear constrains to achieve monotonicity. Another monotonic scheme utilized fifth interpolation polynomial coupled with shape-preserving derivative estimates to be the high-order interpolation scheme of semi-Lagrangian advection algorithms. Results of monotone schemes are presented for two dimensional non-divergent rotational field, one dimensional water vapor advection process and two dimensional warm cloud model. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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