A stable and accurate control-volume technique based on integrated radial basis function networks for fluid-flow problems

Radial basis function networks (RBFNs) have been widely used in solving partial differential equations as they are able to provide fast convergence. Integrated RBFNs have the ability to avoid the problem of reduced convergence-rate caused by differentiation. This paper is concerned with the use of integrated RBFNs in the context of control-volume discretisations for the simulation of fluid-flow problems. Special attention is given to (i) the development of a stable high-order upwind scheme for the convection term and (ii) the development of a local high-order approximation scheme for the diffusion term. Benchmark problems including the lid-driven triangular-cavity flow are employed to validate the present technique. Accurate results at high values of the Reynolds number are obtained using relatively-coarse grids

A continuum-microscopic method based on IRBFs and control volume scheme for viscoelastic fluid flows

A numerical computation of continuum-microscopic model for visco-elastic flows based on the Integrated Radial Basis Function (IRBF) Control Volume and the Stochastic Simulation Techniques (SST) is reported in this paper. The macroscopic flow equations are closed by a stochastic equation for the extra stress at the microscopic level. The former are discretised by a 1D-IRBF-CV method while the latter is integrated with Euler explicit or Predictor-Corrector schemes. Modelling is very efficient as it is based on Cartesian grid, while the integrated RBF approach enhances both the stability of the procedure and the accuracy of the solution. The proposed method is demonstrated with the solution of the start-up Couette flow of the Hookean and FENE dumbbell model fluids

A Multiscale Method Based on the Fibre Configuration Field, IRBF and DAVSS for the Simulation of Fibre Suspension Flows

In this paper, an Integrated Radial Basis Function (IRBF)-based multiscale method is used to simulate the rheological properties of dilute fibre suspensions. For the approach, a fusion of the IRBF computation scheme, the Discrete Adaptive Viscoelastic Stress Splitting (DAVSS) technique and the Fibre Configuration Field has been developed to investigate the evolution of the flow and the fibre configurations through two separate computational processes. Indeed, the flow conservation equations, which are expressed in vorticity-stream function formulation, are solved using IRBF-based numerical schemes while the evolution of fibre configuration fields governed by the Jeffery’s equation is captured using the principle of Brownian Configuration Fields. The two procedures are coupled together by the Lipscomb expression which is used to determine the fibre stress of dilute fibre suspensions. Owing to advantages of the IRBF scheme and the DAVSS technique, the present method yields a more accurate solution and faster convergence rate. The simulation method is verified and its capability is demonstrated with the fibre suspension flows through two parallel plates, a circular tube and the 4:1 and 4.5:1 axisymmetric contraction geometries which are usually chosen to test a numerical method because of the challenging nature of these problems

RBFN stochastic coarse-grained simulation method: Part I - Dilute polymer solutions using Bead-Spring Chain models

In this paper, dynamic behaviours of dilute polymer solutions of various bead-spring chain models in shear flow are studied using a coarse-grained method based on the Integrated Radial Basis Function Networks (IRBFNs) and stochastic technique. The velocity field governed by the macroscopic conservation equations is determined by the IRBFN-based method, whereas the evolution of configurations of polymer chains governed by the diffusion stochastic differential equations are captured by the Brownian Configuration Field (BCF) approach. The system of micro-macro equations is closed by the Kramers’ expression, which allows for the determination of the polymer stresses in terms of BCF configurations. In this work, all nonlinear effects in a BSC model such as hydrodynamic interaction and excluded volume are considered. Since the simulation requires a considerable computational effort, parallel calculations are performed where possible. As an illustration of the method, the start-up planar Couette flow is examined, in which the evolution of viscometric functions such as shear stress, the first and the second normal stress differences is assessed with various BSC models

4th International Conference on Computational Methods (ICCM 2012)

In this paper, topology optimization is applied in optimizing tunnel reinforcement. Nonlinear behavior of geotechnical material is considered to illustrate the practical material behavior under working condition. The adjoint method is used to derive the nonlinear sensitivities. A revised bi-directional evolutionary optimization (BESO) is used to maximize the structural stiffness of reinforced tunnel with a prescribed volume of reinforcement. The developed BESO method is illustrated in a simple example of tunnel reinforcement design to verify the proposed approach

A numerical scheme based on local integrated RBFNs and Cartesian grids for solving second-order elliptic problems in two dimensions

This paper reports a new Cartesian-grid computational technique, based on local integrated radial-basis-function networks (IRBFNs), for the solution of second-order elliptic differential problems defined on two-dimensional regular and irregular domains. At each grid point, only neighbouring nodes are activated to construct the IRBFN approximations. Local IRBFNs are introduced into two different schemes for discretisation of partial differential equations, namely point collocation and control-volume (CV)/subregion-collocation. Numerical experiments indicate that the latter outperforms the former regarding accuracy. Moreover, the proposed local IRBFN CV method shows a similar level of the matrix condition number and a significant improvement in accuracy over a linear CV method