Numerical Calculation Of Fluid Flow Research Articles

Pore-scale modelling of fluid flow in porous media using the projection method for incompressible Navier-Stokes equations in irregular domains

This paper presents the results of numerical simulation of incompressible viscous flow in porous media, which comprise periodically arranged cylinders. This simulation is based on the numerical solution of the incompressible Navier-Stokes equations in irregular domains using the projection method on staggered grids, where the irregular boundary is represented by its level-set function at the pore-scale level. The main problem in numerical calculation of fluid flow through porous media occurs when the value of the porosity is close to 1 or is close to the threshold value since it is necessary to take a very fine numerical mesh, which requires additional computing power and increases the calculation time. There are exact analytical solutions for simple types of porous media which consist of periodically arranged cylinders. In this paper, the permeabilities of these porous media were numerically calculated and compared with the previous works based on the numerical solution of the Lattice-Boltzmann equation in irregular domains, when the fluid flow obeys Darcy’s law. The comparison of numerical and theoretical values of porosity shows that this method is sufficiently accurate for porosity values φ=0.2–0.8.

A pore network model for calculating pressure drop in packed beds of arbitrary‐shaped particles

AbstractA pore network model is built to predict pressure drop in packed beds of arbitrary‐shaped particles, using a method that consists of particle packing by the rigid body technique, pore network construction by the maximal sphere algorithm, and numerical calculation of fluid flow. The pore network model is firstly validated by comparing with experiments, Ergun‐type equations, and particle‐resolved computational fluid dynamics (CFD). The pore network model is as accurate as the particle‐resolved CFD, and is remarkably two to three orders of magnitude less computationally intensive. Then, the pore network model is used to calculate the pressure drops in the beds packed with particles of different shapes and sizes, as well as using different flow media. These calculation results prove the versatility of the pore network model. This work provides an accurate yet efficient pore network model for predicting pressure drop, which should be a powerful tool for designing packed beds.

Numerical Calculation of Fluid Flow in a Continuous Casting Tundish

Placement in the middle retaining wall package, aimed at controlling the flow of liquid steel forms, so that movement of a reasonable level remained stable, while reducing interference from turbulence and dead zones, molten steel in order to extend the average stay of removal in favor of inclusion to improve the cleanliness of molten steel. Keywords:Tundish; Retaining Wall; Flow field; Mathematical Modeling; Inclusion;Optimization setting

Erratum to “A study on preconditioning iterative methods and relativity of pressure in the numerical calculation of fluid flow” by Hiroyuki Hirano, Hideto Yoshida, Hiroyuki Ozoe, and Naotaka Okamoto, Numerical Methods for Partial Differential Equations (2004) 20(5) 789–802

AbstractThe original article to which this Erratum refers was published in Numerical Methods for Partial Differential Equations (2004) 20(5) 789–802

A study on preconditioning iterative methods and relativity of pressure in the numerical calculation of fluid flow

AbstractThis article presents the effect of preconditioning iterative methods on boundary conditions of the pressure‐correction in the numerical computation of fluid flow with known velocity components on all boundaries using the SIMPLE algorithm. In such computation, a set of solutions of the pressure‐correction is indefinite, because only the Neumann condition is imposed on all boundaries. However, solutions become unique if the value of pressure‐correction is fixed at least on one boundary point, and the Dirichlet condition is additionally imposed. Though both conditions must give exactly the same velocity and temperature fields, this problem arises from the relativity of the pressure. The mathematical illustration for this problem is provided using the numerical computation of the natural convection in an enclosure. It is concluded that the preconditioner adopted and the condition that only the Neumann condition on all boundaries is given are effective to reduce the number of iterations in solving the linear system of equations of the pressure‐correction at the computation of the natural convection. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2004

Methods of Numerically Analyzing and Visually Measuring Transport Phenomena in Chemical Equipment. Acceleration of Numerical Calculation of Fluid Flow and Heat Transfer by Preconditioning Iterative Method.

Methods of Numerically Analyzing and Visually Measuring Transport Phenomena in Chemical Equipment. Acceleration of Numerical Calculation of Fluid Flow and Heat Transfer by Preconditioning Iterative Method.

How much pressure drop is necessary for heat transfer?

In many technical applications, heat has to be transferred from a fluid to a wall. To do this efficiently in a short time and confined volume, the fluid has to be moved by applying a pressure difference. In refrigeration and power processes working with ideal gases, the pressure drop in the heat exchangers plays an important role in the overall efficiency of the cycle. The present work investigated whether the necessary pressure drop to obtain a certain amount of heat transfer can be derived from basic principles at least for Reynolds numbers below 2000. It was found that there exists a lower limit on the order of magnitude of 2 pressure heads per transfer unit. This figure is slightly dependent on the Prandtl number of the fluid. Real heat exchanger geometries have values higher than this minimum value, the magnitude depending on simple shape factors, which were derived from numerical fluid flow calculations and with published experimental data. This work identified how the ideal inner geometry of a regenerator for regenerative power and refrigeration processes should look like. [Work is supported by BMBF Grant No. 13N6619/0.]

Numerical calculation of fluid flow in a continuous casting tundish

The deposition of deoxidation and reoxidation products in continuous casting tundish nozzles results in poor surface quality of the cast product and in extreme cases, disruption of the operating schedule. Since the flow of steel in the tundish is central to the behavior of nonmetallic inclusions in the tundish, the details of the flow field are determined numerically by appropriate solutions of the equations of change. The effects of the changes of the internal configuration of the tundish and various casting parameters on the computed velocity fields, particle trajectories, and particle residence times are investigated. The conclusions drawn from the computed results are compared with the results of various independent water model studies.

Recent extensions to Eulerian methods for numerical fluid dynamics

The paper is a review of Eulerian methods for numerical fluid dynamics carried out at the Los Alamos Scientific Laboratory (USA) under the direction of well-known scientists. A new solution technique for the difference equations is suggested. There are considered flows at very low Reynolds numbers as well as the problems of atmospheric dynamics, turbulence models in numerical fluid flow calculations and so on.