Fluid Flow In Complex Geometries Research Articles

Development of pressure-based composite multigrid methods for complex fluid flows

Progress in the development of a multiblock, multigrid algorithm, and a critical assessment of the κ-ε two-equation turbulent model for solving fluid flows in complex geometries is presented. The basic methodology employed is a unified pressure-based method for both incompressible and compressible flows, along with a TVD-based controlled variation scheme (CVS), which uses a second-order flux estimation bounded by flux limiters.Performance of the CVS is assessed in terms of its accuracy and convergence properties for laminar and turbulent recirculating flows as well as compressible flows containing shocks. Several other conventional schemes are also employed, including the first-order upwind, central difference, hybrid, second-order upwind and QUICK schemes. For better control over grid quality and to obtain accurate solutions for complex flow domains, a multiblock procedure is desirable and often a must.Here, a a composite grid algorithm utilizing patched (abutting) grids is discussed and a conservative flux treatment for interfaces between blocks is presented.A full approximation storage-full multigrid (FAS-FMG) algorithm that is incorporated in the flow solver for increasing the efficiency of the computation is also described. For turbulent flows, implementation of the κ-ε two-equation model and in particular the wall functions at solid boundaries is also detailed.In addition, different modifications to the basic k-e model, which take the non-equilibrium between the production and dissipation of κ and ε and rotational effects into account, have also been assessed.Selected test cases are used to demonstrate the robustness of the solver in terms of the convection schemes, the multiblock interface treatment, the multigrid speedup and the turbulence models.

FINITE-VOLUME MULTIGRID CALCULATION OF NATURAL-CONVECTION FLOWS ON UNSTRUCTURED GRIDS

This article presents details and performance of a pressure-based multigrid procedure for natural-convection fluid flows in complex geometries. A control-volume finite-element method using triangular elements is employed to discretize the governing equations. The multigrid technique provides rapid convergence of the numerical solution. Three different geometries are investigated, and the performance of the method at several grid densities and Rayleigh numbers is reported. Also, representative flow fields and temperature contours are presented.

Prediction of Heat and Fluid Flow in Complex Geometries Using General Orthogonal Coordinates

Prediction of Heat and Fluid Flow in Complex Geometries Using General Orthogonal Coordinates

A method for computing three dimensional flows using non‐orthogonal boundary‐fitted co‐ordinates

AbstractFor three‐dimensional fluid flows in complex geometries, it is convenient to make predictions using a non‐orthogonal boundary‐fitted mesh. The present paper describes an economical method of solving the equations of motion for two and three dimensional problems using such meshes. The locations on the mesh at which the depenent variables are calculated, and the methods used to solve the equations, are key issues in the development of a successful algorithm; these are discussed in the present paper. Results obtained when the proposed method is applied to several problems are also described. The method is intended for flows in which compressibility effects do not dominate.

FIDAP (A Fluid Dynamics Analysis Program)

This paper describes the program FIDAP, a general purpose finite element code for simulating steady state or transient two-dimensional, axi-symmetric or three-dimensional incompressible fluid flows in complex geometries, including (if required) the effects of heat transfer. Many different classes of problems are amenable to analysis including isothermal Newtonian and non-Newtonian flows, natural and/or forced convection problems and atmospheric flows. A companion graphics post-processor program FIPOST, allows the production of velocity vector, pressure contour, streamline, vorticity contour, temperature contour and time history plots for two- or three-dimensional simulations.