LES of Compressible Turbulent Annular Pipe Flow With a Rotating Wall

2003 ◽  
Author(s):  
Joon Sang Lee ◽  
Xiaofeng Xu ◽  
R. H. Pletcher
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Outer Wall ◽  
Navier Stokes ◽  
Subgrid Scale ◽  
Turbulent Structures ◽  
Navier Stokes Equations ◽  
Rotating Wall ◽  
Annular Pipe

Flow in an annular pipe with and without a wall rotating about its axis was investigated at moderate Reynolds numbers. The compressible filtered Navier-Stokes equations were solved using a second order accurate finite volume method. Low Mach number preconditioning was used to enable the compressible code to work efficiently at low Mach numbers. A dynamic subgrid-scale stress model accounted for the subgrid-scale turbulence. When the outer wall rotated, a significant reduction of turbulent kinetic energy was realized near the rotating wall and the intensity of bursting effects appeared to decrease. This modification of the turbulent structures was related to the vortical structure changes near the rotating wall. It has been observed that the wall vortices were pushed in the direction of rotation and their intensity increased near the non-rotating wall. The consequent effect was to enhance the turbulent kinetic energy and increased the intensity of the heat transfer rate there.

Effects of Wall Rotation on Heat Transfer to Annular Turbulent Flow: Outer Wall Rotating

2004 ◽  
Vol 127 (8) ◽  
pp. 830-838 ◽  
Author(s):  
Joon Sang Lee ◽  
Xiaofeng Xu ◽  
Richard H. Pletcher
Keyword(s):  
Heat Transfer ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Outer Wall ◽  
High Heat ◽  
High Heat Flux ◽  
Subgrid Scale ◽  
Turbulent Structures ◽  
Rotating Wall

Abstract Simulations were conducted for air flowing upward in a vertical annular pipe with a rotating outer wall. Simulations concentrated on the occurrence of laminarization and property variations for high heat flux heat transfer. The compressible filtered Navier-Stokes equations were solved using a second-order accurate finite volume method. Low Mach number preconditioning was used to enable the compressible code to work efficiently at low Mach numbers. A dynamic subgrid-scale stress model accounted for the subgrid-scale turbulence. When the outer wall rotated, a significant reduction of turbulent kinetic energy was realized near the rotating wall and the intensity of bursting appeared to decrease. This modification of the turbulent structures was related to the vortical structure changes near the rotating wall. It has been observed that the wall vortices were pushed in the direction of rotation and their intensity increased near the nonrotating wall. The consequent effect was to enhance the turbulent kinetic energy and increase the Nusselt number there.

scholarly journals AUTOMATIC INSERTION OF A TURBULENCE MODEL IN THE FINITE ELEMENT DISCRETIZATION OF THE NAVIER–STOKES EQUATIONS

2009 ◽  
Vol 19 (07) ◽  
pp. 1139-1183 ◽  
Author(s):  
CHRISTINE BERNARDI ◽  
TOMÁS CHACÓN REBOLLO ◽  
FRÉDÉRIC HECHT ◽  
ROGER LEWANDOWSKI
Keyword(s):  
Finite Element ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
A Posteriori Error Estimates ◽  
Navier Stokes ◽  
Mesh Adaptivity ◽  
Finite Element Discretization ◽  
Navier Stokes Equations ◽  
Element Discretization

We consider the finite element discretization of the Navier–Stokes equations locally coupled with the equation for the turbulent kinetic energy through an eddy viscosity. We prove a posteriori error estimates which allow to automatically determine the zone where the turbulent kinetic energy must be inserted in the Navier–Stokes equations and also to perform mesh adaptivity in order to optimize the discretization of these equations. Numerical results confirm the interest of such an approach.

scholarly journals Simulations of Moving Effect of Coastal Vegetation on Tsunami Damping

2016 ◽  
Author(s):  
Ching-Piao Tsai ◽  
Ying-Chi Chen ◽  
Tri Octaviani Sihombing ◽  
Chang Lin
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Wave Height ◽  
Stokes Equations ◽  
Coastal Vegetation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Turbulent Closure ◽  
Gmo Model

Abstract. A coupled wave-vegetation simulation is presented for the moving effect of the coastal vegetation on tsunami wave height damping. The problem is idealized by solitary wave propagating on a group of emergent cylinders. The numerical model is based on general Reynolds-averaged Navier-Stokes equations associated with renormalization group turbulent closure model by using volume of fluid technique. The general moving object (GMO) model developed in CFD code Flow-3D is applied to simulate the coupled motion of vegetation with wave dynamically. The damping of wave height and the turbulent kinetic energy dissipation as waves passed over both moving and stationary cylinders are discussed. As comparing with the stationary cylinders, it obtains markedly less wave height damping and turbulent kinetic energy dissipation by the moving cylinders. The result implies that the wave decay by the coastal vegetation might be overestimated if the mangrove vegetation was represented as stationary state.

scholarly journals Simulations of moving effect of coastal vegetation on tsunami damping

2017 ◽  
Vol 17 (5) ◽  
pp. 693-702 ◽  
Author(s):  
Ching-Piao Tsai ◽  
Ying-Chi Chen ◽  
Tri Octaviani Sihombing ◽  
Chang Lin
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Wave Height ◽  
Stokes Equations ◽  
Coastal Vegetation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Turbulent Closure ◽  
Computational Fluid Dynamics Cfd ◽  
Gmo Model

Abstract. A coupled wave–vegetation simulation is presented for the moving effect of the coastal vegetation on tsunami wave height damping. The problem is idealized by solitary wave propagation on a group of emergent cylinders. The numerical model is based on general Reynolds-averaged Navier–Stokes equations with renormalization group turbulent closure model by using volume of fluid technique. The general moving object (GMO) model developed in computational fluid dynamics (CFD) code Flow-3D is applied to simulate the coupled motion of vegetation with wave dynamically. The damping of wave height and the turbulent kinetic energy along moving and stationary cylinders are discussed. The simulated results show that the damping of wave height and the turbulent kinetic energy by the moving cylinders are clearly less than by the stationary cylinders. The result implies that the wave decay by the coastal vegetation may be overestimated if the vegetation was represented as stationary state.

scholarly journals Effect of Baffles on the Sloshing in Road Tankers Carrying LPG: A Comparative Numerical Study

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
J. L. Bautista-Jacobo ◽  
E. Rodríguez-Morales ◽  
J. J. Montes-Rodríguez ◽  
H. Gámez-Cuatzín
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Numerical Study ◽  
Interface Velocity ◽  
Vehicle Control ◽  
Navier Stokes ◽  
Type I ◽  
Type Ii ◽  
Navier Stokes Equations

This work presents a comparative numerical study of the effect of using baffles, and its design, on the behavior of sloshing in a partially filled road tanker carrying LPG. Navier-Stokes equations and standardk-εturbulence model are used to simulate fluid movement; the Volume of Fluid (VOF) method is used to track the liquid-gas interface. Velocity distributions, sloshing stabilization times, and contours of turbulent kinetic energy, which are of high importance in choosing the best design of baffles, are shown. The results show sloshing stabilization times of 22 and 21 s for road tankers with cross-shaped (Type I) and X-shaped (Type II) baffles, respectively, finding lower values of turbulent kinetic energy for Type II design, being, therefore, the best design of baffles for damping of sloshing and vehicle control among studied ones.

scholarly journals INVESTIGATION OF HEAT DISTRIBUTION PROCESSES ON THE INNER SURFACE OF THE ENCLOSING STRUCTURE, TAKING INTO ACCOUNT THE MOVEMENT OF AIR IN THE BOUNDARY AREA BETWEEN THE DEVICE AND FENCING

2019 ◽  
Vol 16 (32) ◽  
pp. 345-361
Author(s):  
B. A. UNASPEKOV ◽  
Z. O. ZHUMADILOVA ◽  
S. S. AUELBEKOV ◽  
A. S. TAUBALDIEVA ◽  
G. B. ALDABERGENOVA
Keyword(s):  
Stokes Equations ◽  
Outer Wall ◽  
Conjugate Problem ◽  
Navier Stokes ◽  
Geometrical Parameters ◽  
Downward Flow ◽  
Navier Stokes Equations ◽  
Boundary Area ◽  
Air Mass ◽  
Hydrodynamic Motion

A study was made of the nature of the movement of air mass in the space between the device that warms the room and the confining outer wall of the room. The hydrodynamic motion of the air mass was simulated on the basis of the two-dimensional in space Navier-Stokes equations and the convective heat conduction equation to find out a detailed picture of the physical processes that occur. Also for some particular cases, analytical solutions were obtained for the conjugate problem, where the movement of air is caused by its thermal expansion and the action of gravity in areas with different densities (Archimedes' forces). The simulation of more complex types of air movement with the formation of vortex flows using numerical methods and the corresponding program codes written in C++. It was found that the movement of air mass in the space between the device and the fence strongly depends not only on the temperature of the device, the wall, and the outside air. It was revealed that hydrodynamics and heat transfer are significantly influenced by two geometrical parameters: the distance between the device and the wall, and the distance from the flooring to the bottom of the device. In particular, a thin layer of the downward flow of cold air along the fence and above the floor is possible. The condition for the occurrence of such a downward flow has been found, it is determined by the ratio of the temperature of the wall, the device, and the average temperature in the room.

scholarly journals Numerical simulation of supersquare patterns in Faraday waves

2015 ◽  
Vol 772 ◽  
Author(s):  
L. Kahouadji ◽  
N. Périnet ◽  
L. S. Tuckerman ◽  
S. Shin ◽  
J. Chergui ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Outer Wall ◽  
Wave Pattern ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Critical Wavelength ◽  
Characteristic Wavelength ◽  
Cylindrical Domains ◽  
Lagrangian Tracking

We report the first simulations of the Faraday instability using the full three-dimensional Navier–Stokes equations in domains much larger than the characteristic wavelength of the pattern. We use a massively parallel code based on a hybrid front-tracking/level-set algorithm for Lagrangian tracking of arbitrarily deformable phase interfaces. Simulations performed in square and cylindrical domains yield complex patterns. In particular, a superlattice-like pattern similar to those of Douady & Fauve (Europhys. Lett., vol. 6, 1988, pp. 221–226) and Douady (J. Fluid Mech., vol. 221, 1990, pp. 383–409) is observed. The pattern consists of the superposition of two square superlattices. We conjecture that such patterns are widespread if the square container is large compared with the critical wavelength. In the cylinder, pentagonal cells near the outer wall allow a square-wave pattern to be accommodated in the centre.

scholarly journals A Modified Gas-Kinetic Scheme for Turbulent Flow

2014 ◽  
Vol 16 (1) ◽  
pp. 239-263 ◽  
Author(s):  
Marcello Righi
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Kinetic Energy ◽  
Turbulent Boundary Layer ◽  
Numerical Scheme ◽  
Stokes Equations ◽  
Kinetic Scheme ◽  
Navier Stokes ◽  
Turbulent Stress ◽  
Navier Stokes Equations

AbstractThe implementation of a turbulent gas-kinetic scheme into a finite-volume RANS solver is put forward, with two turbulent quantities, kinetic energy and dissipation, supplied by an allied turbulence model. This paper shows a number of numerical simulations of flow cases including an interaction between a shock wave and a turbulent boundary layer, where the shock-turbulent boundary layer is captured in a much more convincing way than it normally is by conventional schemes based on the Navier-Stokes equations. In the gas-kinetic scheme, the modeling of turbulence is part of the numerical scheme, which adjusts as a function of the ratio of resolved to unresolved scales of motion. In so doing, the turbulent stress tensor is not constrained into a linear relation with the strain rate. Instead it is modeled on the basis of the analogy between particles and eddies, without any assumptions on the type of turbulence or flow class. Conventional schemes lack multiscale mechanisms: the ratio of unresolved to resolved scales – very much like a degree of rarefaction – is not taken into account even if it may grow to non-negligible values in flow regions such as shocklayers. It is precisely in these flow regions, that the turbulent gas-kinetic scheme seems to provide more accurate predictions than conventional schemes.

Viscous Flow Computations for Compressor/Combustor Diffuser Design to Allow Air Extraction for IGCC Systems

1991 ◽  
Author(s):  
Ajay K. Agrawal ◽  
Tah-Teh Yang
Keyword(s):  
Coal Gasification ◽  
Stokes Equations ◽  
Outer Wall ◽  
Computational Procedure ◽  
Navier Stokes ◽  
Structural Constraints ◽  
Navier Stokes Equations ◽  
Annular Diffuser ◽  
High Reynolds ◽  
Suction Slot

A computational procedure based on the solution of fully elliptic Navier-Stokes equations on a body-fitted non-orthogonal grid was used to obtain flow fields in annular diffusers with a suction slot at the inner and outer walls. The turbulence effects were simulated by high Reynolds number form of the k-ε model. The calculation method was used to modify an industrial gas turbine (GE MS · 7001F) compressor/combustor annular diffuser to allow extraction of compressed airflow for coal gasification in simplified IGCC Systems. The air for gasification was extracted through a suction slot on the outer wall of the diffuser which was curved to improve the overall performance and to avoid flow separation; both of these insured by providing accelerated flow through the suction slot and nearly constant wall pressure downstream of the slot. Suction slot and outer wall geometries to result in the above conditions were determined by a trial and error procedure. The diffuser’s performance was further improved by extracting 6% of the compressed air through a slot at the inner wall, kept straight due to structural constraints. The resulting diffuser arrangement was relatively insensitive to the upstream disturbances.

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