Turbulent Flow Of Incompressible Fluid Research Articles

A control‐volume based finite element method for three‐dimensional incompressible turbulent fluid flow, heat transfer, and related phenomena

AbstractA control‐volume based finite element method of equal‐order type for three‐dimensional incompressible turbulent fluid flow, heat transfer, and related phenomena is presented. The discretization equations are based mainly on the physics of the phenomena under consideration, more than on mathematical arguments. Special emphasis is devoted to the discretization of the convective terms and the continuity equation, and to the treatment of the boundary conditions imposed by the use of a high Reynolds k‐ϵ, type turbulence model. The pressure‐velocity coupling in the fluid flow calculation is made from a derivative of the original SIMPLER method, without pressure correction. The discretized equations are solved in a sequential, rather than a coupled, form with significant advantage in the required computer time and storage. The method is an extension of a former version proposed by us for two‐dimensional, laminar problems, and is here successfully applied to the following situations: three‐dimensional deflected turbulent jet, and flows in 90° and 45° junctions of ducts with rectangular cross sections. The calculated results are in very good agreement with the experimental and numerical (obtained with the well established finite difference method) data available in the literature.

Two-layer turbulent flow over a rough rotating surface

A model of turbulent incompressible fluid flow over a rough surface under the action of the Coriolis force with a turbulent transfer coefficient corresponding to the Prandtl mixing length is proposed. A solution of the problem, asymptotic in the small Coriolis parameter, is presented for horizontally uniform steady-state flow. It is shown that for a small Coriolis parameter the velocity profile and the turbulent transfer coefficient can differ substantially from the limiting expressions known from Prandtl theory. The smaller the roughness coefficient, the greater the difference.

Flow Features to Control Thermally Induced Convection in a Vertical Laminar Flow Cleanroom

This paper presents results of a flow simulation study of convection heat currents above a heat source in a vertical laminar flow (VLF) cleanroom as determined both experimentally and computationally. Typical clcanroom operations have numerous pieces of equipment that generate heat— thus the importanec of this study. The experiment was carried out in a full-scale mockup of a cleanroom. Temperature distributions above an electrical hot plate were measured for 12 airflow velocities and four heat source levels. The results showed that when the mean downward airflow velocity was 0.20 m/s or greater, the plume of heated air was completely suppressed and rose only 30 cm above the heat source. The relation between the convection current zone and the Richardson number was determined. Computer models simulating the turbulent incompressible fluid flow in a Cartesian coordinate system were applid to analyze the three-dimensional heat currents inside the VLF cleanroom and to prediet the temperature and velocity distributions. The velocity distributions clearly indicated the magnitude of the area within which the heat current disturbed the vertical flow. Comparisons between the experimental findings and the calculated results provided significant information on how to apply the computer simulation to a practical design.

Turbulent incompressible fluid flow in a channel with unilateral mass transfer

Turbulent incompressible fluid flow in a channel with unilateral mass transfer

Numerical and physical modeling of turbulent flow around a plate with two transverse ribs

Results are presented of a numerical and experimental investigation of turbulent incompressible fluid flow near a horizontal plate on which one and two interceptors are installed.

Analysis of the drag of two discs in a turbulent incompressible fluid flow

The effect of reducing the drag of two discs is investigated by using difference modeling of their flow by using the two-parameter k — ɛ turbulence model.

Influence of channel walls on the formation of vortices behind a wedge

A study is made of the influence of channel walls on the occurrence of periodic vortex formation in the wake of a wedge in a turbulent flow of incompressible fluid. The results of numerical simulation of the flow are confirmed by experimental data. The influence of the blocking of the flow by the body on the existence of the regime of vortex formation is explained by means of a linear analysis of the stability of the non-parallel flow in the near wake.

Use of the equation for turbulent viscosity to describe the flow near a rough surface

An investigation of the flow at a rough surface, as well as in pipes and channels with rough walls, is one of the most important problems of applied hydrodynamics. Results of classical investigations, in which the most important flow properties near a rough surface are clarified, are generalized in [1–3]. These investigations are the basis for the construction of numerous semiempirical theories using the “mixing path∝ model of L. Prandtl (for instance, [4–6]). However, despite their simplicity these methods possess all the disadvantages inherent in the Prandtl theory: They are not universal, they describe the transition from the laminar to the turbulent mode poorly, and they are not applicable for the computation of complex non-self-similar flows. Meanwhile, an analysis of the experimental results obtained in [7], for example, indicates an extremely complex flow structure both in the neighborhood of the rough surface and far away from it. Models using the differential equation of the kinetic energy of turbulence have recently been developed to describe turbulent flow near a rough surface [8]. The possibilities of applying a model using the equation for turbulent viscosity to close the problem [9] are analyzed in this paper in an example of a steady turbulent incompressible fluid flow in a circular pipe with rough walls.

On Turbulent Flow Between Parallel Plates

Abstract The Reynolds equations of motion of turbulent flow of incompressible fluid have been studied for turbulent flow between parallel plates. The number of these equations is finally reduced to two. One of these consists of mean velocity and correlation between transverse and longitudinal turbulent-velocity fluctuations u 1 ′ u 2 ′ ¯ only. The other consists of the mean pressure and transverse turbulent-velocity intensity. Some conclusions about the mean pressure distribution and turbulent fluctuations are drawn. These equations are applied to two special cases: One is Poiseuille flow in which both plates are at rest and the other is Couette flow in which one plate is at rest and the other is moving with constant velocity. The mean velocity distribution and the correlation u 1 ′ u 2 ′ ¯ can be expressed in a form of polynomial of the co-ordinate in the direction perpendicular to the plates, with the ratio of shearing stress on the plate to that of the corresponding laminar flow of the same maximum velocity as a parameter. These expressions hold true all the way across the plates, i.e., both the turbulent region and viscous layer including the laminar sublayer. These expressions for Poiseuille flow have been checked with experimental data of Laufer fairly well. It also shows that the logarithmic mean velocity distribution is not a rigorous solution of Reynolds equations.