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An MHD Stokes eigenvalue problem and its approximation by a spectral collocation method
Computers & Mathematics with Applications ( IF 2.9 ) Pub Date : 2020-09-18 , DOI: 10.1016/j.camwa.2020.09.002
Önder Türk

An eigenvalue problem is introduced for the magnetohydrodynamic (MHD) Stokes equations describing the flow of a viscous and electrically conducting fluid in a duct under the influence of a uniform magnetic field. The solution of the eigenproblem is approximated by using a spectral collocation method that is based on vanishing the residual equation at the collocation points on the physical domain which are chosen to be the Chebyshev–Gauss–Lobatto points. As the solutions are sought in the physical space, the approximations to the derivatives of the unknowns are directly evaluated. The equations are formulated in the primitive variables, and hence with inclusion of the continuity equation, the discretization of the operator results in a generalized eigenproblem with zero diagonal entries. Therefore, a penalty method is applied to circumvent the degeneracy where a perturbed form of the problem is considered, and a zero mean pressure value is introduced. The numerical prospects of the algorithm are investigated and demonstrated by a number of characteristic tests. The key features of interest are the effects of introducing a magnetic field on the eigenspectrum focusing mainly on the change of the fundamental eigenpairs, and the consequential variation of the eigenstructure with the magnetic field. The mechanisms that underlie these effects are examined by the numerical model proposed, the implications of these effects are presented, and it is shown that the flow field is considerably affected with the introduction of a magnetic field into the physical model.



中文翻译:

MHD Stokes特征值问题及其通过谱配点法逼近

为磁流体动力学(MHD)斯托克斯方程引入了一个特征值问题,该方程描述了在均匀磁场影响下管道中的粘性和导电流体的流动。特征问题的解决方案是通过使用一种光谱搭配方法来近似的,该方法基于消失在物理域上的搭配点上的残差方程,这些点被选择为Chebyshev–Gauss–Lobatto点。在物理空间中寻求解决方案时,直接评估未知数导数的近似值。这些方程式用原始变量表示,因此,在包含连续性方程式的情况下,算子的离散化导致对角项为零的广义特征问题。因此,在考虑问题的扰动形式的情况下,采用惩罚方法来避免退化,并引入零平均压力值。该算法的数值前景已通过许多特性测试得到了研究和证明。感兴趣的关键特征是在本征谱上引入磁场的效果,主要集中于基本本征对的变化以及本征结构随磁场的相应变化。通过提出的数值模型检查了这些效应的基础机理,并提出了这些效应的含义,结果表明,在物理模型中引入磁场会大大影响流场。并引入零平均压力值。该算法的数值前景已通过许多特性测试得到了研究和证明。感兴趣的关键特征是在本征谱上引入磁场的效果,主要集中于基本本征对的变化以及本征结构随磁场的相应变化。通过提出的数值模型检查了这些效应的基础机理,并提出了这些效应的含义,结果表明,在物理模型中引入磁场会大大影响流场。并引入零平均压力值。该算法的数值前景已通过许多特性测试得到了研究和证明。感兴趣的关键特征是在本征谱上引入磁场的效果,主要集中于基本本征对的变化以及本征结构随磁场的相应变化。通过提出的数值模型检查了这些效应的基础机理,并提出了这些效应的含义,结果表明,在物理模型中引入磁场会大大影响流场。感兴趣的关键特征是在本征谱上引入磁场的效果,主要集中于基本本征对的变化以及本征结构随磁场的相应变化。所提出的数值模型检查了这些效应的基础机理,并提出了这些效应的含义,结果表明,在物理模型中引入磁场会大大影响流场。感兴趣的关键特征是在本征谱上引入磁场的效果,主要集中于基本本征对的变化以及本征结构随磁场的相应变化。通过提出的数值模型检查了这些效应的基础机理,并提出了这些效应的含义,结果表明,在物理模型中引入磁场会大大影响流场。

更新日期:2020-09-20
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