共查询到19条相似文献，搜索用时 281 毫秒
1.
显式完全平方守恒差分格式在近岸海流数值模拟中的应用 总被引：2，自引：0，他引：2
用显式完全平方守恒差分格式及其改进分解算法对南海月平均流和海面起伏进行了数值模拟，与隐式完全平方守恒差分格式相比，计算时间可省３－５倍，具有良好的时间效益，而且，其计算效果不比稳式完全平方守恒差分格式差。因此，显式完全平方守恒差分格式及其改进分解算法具有良好的实用价值。 相似文献
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黄海冬季环流的数值模拟 总被引：4，自引：1，他引：4
在北黄海和渤海冬季环数值研究的基础上，利用其进一步改进的数值差分格式，对整个黄海的冬季环流进行了数值模拟。数模结果表明，改进的差分格式完全保持了计算海区的总能量和总质量守恒。就环流的总趋势而论，数据模拟结果与由资料所分析的结果几乎完全相同。 相似文献
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近岸浅海潮流数值模型及其应用 总被引：2，自引：0，他引：2
在Ｃａｓｕｌｌｉ提出的半隐式有限差分方法的基础上,通过改进底摩擦力公式以避免在超浅水域底摩擦项过大的缺点,对底摩擦项进行线性化处理以获得隐式效果,对平流项采用适当的差分格式以减小假扩散及对活动边界误差的传播,采用高效的迭代格式提高运算速度,建立适合于近岸浅海的潮流数值模型。该模型有良好的稳定性,计算时间步长不受ＣＦＬ条件的限制,在防城港的潮流模拟中,模型的验证结果良好。 相似文献
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斜压海洋动力学的一种三维数值模式 Ⅰ.动力学方程数值格式 总被引：1，自引：0，他引：1
依据自由海面海洋动力学原始方程建立了一种三维有限差分数值模式,可用于潮波、风暴潮和海流的数值模拟和预报。运动方程和连续方程的数值格式采用内、外模态分离的技术。外模态采用交替方向隐格式,用于计算海面高度和垂直平均流速,时间步长不受Ｃｏｕｒａｎｔ－Ｆｒｉｄｅｒｉｃｈｓ－Ｌｅｗｙ条件限制;内模态采用半隐格式,用于计算海流的垂直２颁布,其时间步长可大于外模态时间步长。模式的计算程度比一般显式模式可快１０倍 相似文献
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流速逆变张量隐式求解方法及其在航道港池流场计算中的应用 总被引：6，自引：1，他引：5
运用高分辨率的边界适应网格进行流体动力学数值计算时,如何提高计算稳定性和减少计算量成为数值求解的关键性问题.在非正交的边界适应坐标系中,每个动量方程中同时出现了两个交叉方向的水位偏导数项,给隐式求解带来困难,而显式格式下的时间步长由于受与空间步长有关的Courant-Friedrichs-Lewy条件限制,计算量成倍增加.本文从广义曲线坐标系下浅海动力学方程组出发,导出了流速的逆变张量所满足的动量方程组,使方程中的水位偏导数项变成了沿某一协变基向量方向占优的形式,方便地采用了交替方向隐式差分格式,从而提高了计算稳定性并减小了计算量.本文通过对澳门海域航道和港池中流场的计算,证实了该模式是一种进行高分辩率数值计算的有效方法. 相似文献
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基于一维阻尼潮波传播方程解析解,从求解数值格式及Heuristic稳定性分析方面,讨论了数值解的精度、计算耗时和摩阻系数选取等问题。研究结果表明:1)Courant数小于1时,潮波方程显格式解的精度略高于隐格式解,计算耗时少于隐格式解;2)为减少计算耗时,潮波方程的隐格式解允许较大的时间步长,但解的精度有所降低,须通过减小底床摩阻系数以保证计算精度;3)隐格式解摩阻系数的选取与Courant数有关,Courant数越大,摩阻系数的选取值比实际值越小,通过理论分析结合数值试验得到了相应的关系式。这些研究结论对实际海域的潮波传播的数值模拟具有重要的应用价值。 相似文献
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给出了解铁磁链方程的1个二阶线性化隐式差分格式；证明了差分解按离散L^2范数的最优阶先验误差估计及稳定性；给出数值算例。 相似文献
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A two-dimensional vertical (2DV) non-hydrostatic boundary fitted model based on a Godunov-type shock-capturing scheme is introduced and applied to the simulation of waves from deep water up to the swash zone. The effects of shoaling, breaking, surf zone dissipation and swash motions are considered. The application of a Godunov-type shock-capturing algorithm together with an implicit solver on a standard staggered grid is proposed as a new approach in the 2DV simulation of large gradient problems such as wave breaking and hydraulic jumps. The complete form of conservative Reynolds averaged Navier–Stokes (RANS) equations are solved using an implicit finite volume method with a pressure correction technique. The horizontal advection of the horizontal velocity is solved by an explicit predictor–corrector method. Fluxes are predicted by an exact Riemann solver and corrected by a downwind scheme. A simple total variation diminishing (TVD) method with a monotonic upstream-centered scheme for conservation laws (MUSCL) limiter function is employed to eliminate undesirable oscillations across discontinuities. Validation of the model is carried out by comparing the results of the simulations with several experimental test cases of wave breaking and run-up and the analytical solution to linear short waves in deep water. Promising performance of the model has been observed. 相似文献
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在中国近海的不少海域曾经发现相当强的内潮现象,例如赵俊生(1992)报道了渤海海峡的内潮现象, Yamashiro(1988)在东海陆坡处亦发现内潮的存在。特别是Amoco石油公司在南海陆坡处进行了一年多的海流测量,测得最大的全日潮流振幅可超过60cm/s,这里正压潮流小于10cm/s,故观测到的潮流主要与内潮有关。迄今关于内潮的数值模式大多将表面潮作为已知输入条件、从而使模式的应用受到较多限制(Jiang and Fang，1992)。Heaps(1983)曾发展了一种自由海面多层模式,但他们忽略了非线性平流项,这无疑也会损失许多有用信息。本文将叙述一种自由海面的多层模式,它能够同时模拟表面潮和内潮,并包含了非线性平流项。 相似文献
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预估修正法对河口海岸海洋模式稳定性的提高 总被引：4，自引：0，他引：4
河口海岸海洋模式时间差分为欧拉前差格式，在涡动粘滞系数较小的情况下，模式存在着弱不稳定性。为提高模式的稳定性，采用预估修正法对模式中科氏力项作半隐式处理。首先在理论上证明了模式稳定性的提高，随后设计一个高分辨率网格，考虑实际岸线和水深、边界通量、密度梯度力和风应力，把模式应用于冬季渤、黄、东海环流的数值模拟，数值试验也证明了模式稳定性的提高。改进后的河口海岸海洋模式较成功地模拟出了冬季渤、黄、东海环流（黑潮、台湾暖流、对马暖流、黄海暖流和沿岸流），与实际观测和研究结果较为一致。 相似文献
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lNTRODUCTIONAsoneofthenumericalcalculationmethodsinvolvingfluiddynamicsinnearshoreareas,theboundaryfittedgridmethodhasmanyadvantagessuchasfittingboundaries,beingsuitableforengineeringconstructionswithsmallscalesandimprovingtheaccuracybydensifyinggridpointsintheinterestedareas'Incomparisonwiththefiniteelementmethodwithnon-uniformgrids,theboundary-fittedgridmodelismorewidelyusedbecauseofitssuperioritiesinusingthematurefi-nitedifferenceschemeandinoccupyingsma1lcomputermemory(Sheng,l986;Haase.… 相似文献
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提出了一种模拟三维海流运动的隐式差分方法,井给出其计算步骤。通过对该差分方法的稳定性分析可以发现,它的时间步长取值有较大的灵活性。该方法被用于崖门海域的海流模拟。实例计算表明,该差分方法计算过程稳定,计算结果合理,能较好地反映出三维海流运动的特征。 相似文献
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A depth-integrated, non-hydrostatic model with hybrid finite difference and finite volume numerical algorithm is proposed in this paper. By utilizing a fraction step method, the governing equations are decomposed into hydrostatic and non-hydrostatic parts. The first part is solved by using the finite volume conservative discretization method, whilst the latter is considered by solving discretized Poisson-type equations with the finite difference method. The second-order accuracy, both in time and space, of the finite volume scheme is achieved by using an explicit predictor-correction step and linear construction of variable state in cells. The fluxes across the cell faces are computed in a Godunov-based manner by using MUSTA scheme. Slope and flux limiting technique is used to equip the algorithm with total variation dimensioning property for shock capturing purpose. Wave breaking is treated as a shock by switching off the non-hydrostatic pressure in the steep wave front locally. The model deals with moving wet/dry front in a simple way. Numerical experiments are conducted to verify the proposed model. 相似文献
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A mode-splitting method is applied to the quasi-3D nearshore circulation equations in generalized curvilinear coordinates. The gravity wave mode and the vorticity wave mode of the equations are derived using the two-step projection method. Using an implicit algorithm for the gravity mode and an explicit algorithm for the vorticity mode, we combine the two modes to derive a mixed difference–differential equation with respect to surface elevation. McKee et al.'s [McKee, S., Wall, D.P., and Wilson, S.K., 1996. An alternating direction implicit scheme for parabolic equations with mixed derivative and convective terms. J. Comput. Phys., 126, 64–76.] ADI scheme is then used to solve the parabolic-type equation in dealing with the mixed derivative and convective terms from the curvilinear coordinate transformation. Good convergence rates are found in two typical cases which represent respectively the motions dominated by the gravity mode and the vorticity mode. Time step limitations imposed by the vorticity convective Courant number in vorticity-mode-dominant cases are discussed. Model efficiency and accuracy are verified in model application to tidal current simulations in San Francisco Bight. 相似文献
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SHI Fengyan DING Pingxing KONG Yazhen
Associate Professor State Key Laboratory of Estuarine Coastal Research East China Normal University Shanghai P. R. China.
Professor State Key Laboratory of Estuarine Coastal Research East China Normal University Shanghai P. R. China.
Senior Engineer State Key Laboratory of Estuarine Coastal Research East China Normal University Shanghai P. R. China. 《中国海洋工程》1999,(2)
Fine grids with small spacing in boundary-fitted coordinates are normally used to treat thecomputation of fluid dynamics for estuarine areas and tidal flats.However,the adoption of Cartesian com-ponents of velocity vectors in this kind of non-orthogonal coordinates will definitely result in a diffculty insolving implicitly the transformed momentum equations,and also complicate the wet-dry point judgementused for flood areas.To solve this problem,equations in terms of generalized contravariant velocityvectors in curvilinear coordinates are derived in the present study,by virtue of which,anAlternative-Direction-Implicit numerical scheme in non-orthogonal grids would then be easily obtained,and wet-dry point judgement would as well be largely simplified.A comparison is made between the explic-it scheme and implicit scheme,showing that the present model is accurate and numerically stable for com-putations of fluid dynamics for estuarine areas and tidal flats. 相似文献