摘要
研究设计了一种二维和三维嵌套、外模态和内模态分离的水动力学数值模式,既可用于潮汐,也可用于风暴潮的数值计算。该模型对全部海区进行二维计算,对其中重点关心的海区同时进行三维计算。在三维计算区域,采用了内、外模态既分离又耦合的计算技术。数值格式采用全部交错的网格结构,三维模型中垂直方向采用σ-坐标代替通常的z-坐标,垂直涡动粘性系数由混合长度理论确定,垂直粘性项采用隐式差分格式。作为算例,本文对南海北部湾潮波进行了细网格的数值计算。
To simulate the vertical structure of oceanic current in an interested area with less computer time a combined two-and three-dimensional numerical model is developed. The 3-D model covers the interested area and the 2-D model covers a larger area. The sea-surface elevation and the depth-mean current are computed from the 2-D model with an explicit scheme, thus the time step is restricted by the Courant-Friedrichs-Lewy condition. In the 3-D domain the sea-surface elevation is known and the current is obtained by solving the momentum equations using an implicit and thus unconditionally stable scheme. The nonlinear terms and the bottom stress calculated in the 3-D model are then fed back to the 2-D computation. Thus, the computations of external mode and internal mode are splitted but coupled, resulting in allowance of much larger time step in 3-D compution.The numerical model is applied to the simulation of the tides and tidal currents in the Beibuwan Gulf (Gulf of Tonkin). The 3-D model covering an area of 2.5°×2.5° to the southwest of Hainan Province is embedded in a 2-D model, which covers the whole area of the Beibuwan Gulf. The horizontal grid spacing is 1/8 degree and the water column in the 3-D model is divided into 5 layers. The time steps in 2-D and 3-D models are 90s and 450s, respectively.The model produced tidal harmonics are in good agreement with the empirical ones. The model produced vertical structure of tidal current is consistent with the observed one and the basical features of both the computed and observed vertical distributions of tidal current agree with the theoretical conclusion advanced by Fang and Ichiye (1983).
出处
《海洋与湖沼》
CAS
CSCD
北大核心
1993年第2期117-125,共9页
Oceanologia Et Limnologia Sinica
关键词
数值模拟
潮汐
流体动力学
潮流
Three-dimensional model Embedding Mode-splitting technique Tide
