Partial Differential Equations in Surface Hydrology, Free Surface Flows, and Ideal Fluid Flows

2021 ◽  
pp. 75-110
Author(s):  
Soumendra Nath Kuiry ◽  
Dhrubajyoti Sen
Author(s):  
I. L. Collings

AbstractSolutions are found to two cusp-like free-surface flow problems involving the steady motion of an ideal fluid under the infinite-Froude-number approximation. The flow in each case is due to a submerged line source or sink, in the presence of a solid horizontal base.


Author(s):  
Omar Abu Arqub

Purpose The purpose of this study is to introduce the reproducing kernel algorithm for treating classes of time-fractional partial differential equations subject to Robin boundary conditions with parameters derivative arising in fluid flows, fluid dynamics, groundwater hydrology, conservation of energy, heat conduction and electric circuit. Design/methodology/approach The method provides appropriate representation of the solutions in convergent series formula with accurately computable components. This representation is given in the W(Ω) and H(Ω) inner product spaces, while the computation of the required grid points relies on the R(y,s) (x, t) and r(y,s) (x, t) reproducing kernel functions. Findings Numerical simulation with different order derivatives degree is done including linear and nonlinear terms that are acquired by interrupting the n-term of the exact solutions. Computational results showed that the proposed algorithm is competitive in terms of the quality of the solutions found and is very valid for solving such time-fractional models. Research limitations/implications Future work includes the application of the reproducing kernel algorithm to highly nonlinear time-fractional partial differential equations such as those arising in single and multiphase flows. The results will be published in forthcoming papers. Practical implications The study included a description of fundamental reproducing kernel algorithm and the concepts of convergence, and error behavior for the reproducing kernel algorithm solvers. Results obtained by the proposed algorithm are found to outperform in terms of accuracy, generality and applicability. Social implications Developing analytical and numerical methods for the solutions of time-fractional partial differential equations is a very important task owing to their practical interest. Originality/value This study, for the first time, presents reproducing kernel algorithm for obtaining the numerical solutions of some certain classes of Robin time-fractional partial differential equations. An efficient construction is provided to obtain the numerical solutions for the equations, along with an existence proof of the exact solutions based upon the reproducing kernel theory.


2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Liu-Chao Qiu ◽  
Yi Liu ◽  
Yu Han

This work presents a three-dimensional two-way coupled method to simulate moving solids in viscous free-surface flows. The fluid flows are solved by weakly compressible smoothed particle hydrodynamics (SPH) and the displacement and rotation of the solids are calculated using the multisphere discrete element method (DEM) allowing for the contact mechanics theories to be used in arbitrarily shaped solids. The fluid and the solid phases are coupled through Newton’s third law of motion. The proposed method does not require a computational mesh, nor does it rely on empirical models to couple the fluid and solid phases. To verify the numerical model, the floating and sinking processes of a rectangular block in a water tank are simulated, and the numerical results are compared with experimental results reported in published literatures. The results indicate that the method presented in this paper is accurate and is capable of modelling fluid-solid interactions with a free-surface.


Author(s):  
Xiang Zhao ◽  
Zhi Yang ◽  
Sijun Zhang ◽  
Chien-Pin Chen

Algebraic multi-grid (AMG) is increasingly used for large practical problems, its parallelization is highly demanded. A parallel algorithm to enhance the robustness and performance for AMG was proposed with regard to unique characteristics of partial differential equations governing fluid flows. A building strategy was developed to accomplish grid coarsening and build the hierarchy of multi-level grids. Moreover an agglomeration approach was proposed, which stems from the consideration of both the physical and mathematical properties of flow fields. The parallelized AMG has demonstrated excellent performances and strong enhancement on many cases.


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