Simulation of Natural Ventilation of Workshop in Large-Scale Iron and Steel Enterprises Based on CFD

2012 ◽  
Vol 170-173 ◽  
pp. 2478-2483
Author(s):  
Yan Long ◽  
Ke Liu ◽  
Shi Ping Jin ◽  
Yan Fu
Keyword(s):  
Numerical Simulations ◽  
Design Optimization ◽  
Theoretical Basis ◽  
Large Scale ◽  
Natural Ventilation ◽  
Two Dimensional ◽  
Iron And Steel ◽  
To Come ◽  
Flow States

Method of CFD was adopted to carry out two-dimensional numerical simulations for internal natural ventilation process of a standard triple-span workshop in iron and steel enterprises with3 different layouts of heat resources. Flow states and relevant parameters of air-fluid in the workshop were obtained to come up with theoretical basis for design, optimization and process layout of natural ventilation in workshops.

Natural Ventilation Design and Optimization of Large-Scale Industrial Workshop

2014 ◽  
Vol 1065-1069 ◽  
pp. 2137-2140
Author(s):  
Xiao Hu Yang ◽  
Yan Long ◽  
Ling Zhao Meng ◽  
Yu Hui Jin
Keyword(s):  
Large Scale ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Orthogonal Experiment ◽  
Structure Design ◽  
Iron And Steel ◽  
Design And Optimization ◽  
Experiment Method ◽  
Orthogonal Experiment Method ◽  
Computational Fluid Dynamics Cfd

In this paper, we used orthogonal experiment method and Computational Fluid Dynamics (CFD) technology to simulate the thermal environment of the iron and steel workshop. By comparing and analyzing the temperature distribution and air flow of workshops with different window structures, we obtained an optimization of natural ventilation design for industrial workshop. The research results can be used for the structure design or reformation of industrial workshops as reference.

scholarly journals The fate of random initial vorticity distributions for two-dimensional Euler equations on a sphere

2015 ◽  
Vol 786 ◽  
pp. 1-4 ◽  
Author(s):  
Paul K. Newton
Keyword(s):  
Numerical Simulations ◽  
Euler Equations ◽  
Large Scale ◽  
Initial Conditions ◽  
Infinite Family ◽  
Small Scale ◽  
Two Dimensional ◽  
Random Initial Conditions ◽  
Long Time ◽  
Initial Vorticity

The paper by Dritschel et al. (J. Fluid Mech., vol. 783, 2015, pp. 1–22) describes the long-time behaviour of inviscid two-dimensional fluid dynamics on the surface of a sphere. At issue is whether the flow settles down to an equilibrium or whether, for generic (random) initial conditions, the long-time solution is periodic, quasi-periodic or chaotic. While it might be surprising that this issue is not settled in the literature, it is important to keep in mind that the Euler equations form a dissipationless Hamiltonian system, hence the set of equations only redistributes the initial vorticity, generating smaller and smaller scales, while keeping kinetic energy, angular impulse and an infinite family of vorticity moments (Casimirs) intact. While special solutions that never settle down to an equilibrium state can be constructed using point vortices, vortex patches and other distributions, the fate of random initial conditions is a trickier problem. Previous statistical theories indicate that the long-time state should be a stationary large-scale distribution of vorticity. By carrying out careful numerical simulations using two different methods, the authors make a compelling case that the generic long-time state resembles a large-scale oscillating quadrupolar vorticity field, surrounded by persistent small-scale vortices. While numerical simulations can never conclusively settle this issue, the results might help guide future theories that seek to prove the existence of such an interesting dynamical long-time state.

SYMMETRIC LARGE-SCALE VELOCITY FIELDS IN TWO-DIMENSIONAL THERMAL CONVECTION

1994 ◽  
Vol 04 (05) ◽  
pp. 1369-1374 ◽  
Author(s):  
J. PRAT ◽  
I. MERCADER ◽  
J.M. MASSAGUER
Keyword(s):  
Stability Analysis ◽  
Velocity Field ◽  
Velocity Profile ◽  
Numerical Simulations ◽  
Linear Stability Analysis ◽  
Thermal Convection ◽  
Vertical Profile ◽  
Large Scale ◽  
Velocity Fields ◽  
Two Dimensional

Recent experiments on thermal convection in finite containers [Krishnamurti & Howard, 1981; Howard & Krishnamurti, 1986] show the presence of flows spanning the largest dimension of the container. Numerical simulations of 2D thermal convection showing large-scale flows of this kind have been presented elsewhere [Prat et al., 1993a, 1993b]. In every known example the large scale velocity field has been found to display a vertical profile either antisymmetric or showing rather small departures from antisymmetry. In contrast, theoretical group arguments support the existence of symmetric velocity profiles. In the present paper it will be shown that large-scale velocity fields with vertically symmetric velocity profile do exist. In spite of these flows not being dominant in the range of parameters explored, their geometry and dynamics will be discussed on the basis of a linear stability analysis.

Vortices in oscillating spin-up

2007 ◽  
Vol 573 ◽  
pp. 339-369 ◽  
Author(s):  
M. G. WELLS ◽  
H. J. H. CLERCX ◽  
G. J. F. VAN HEIJST
Keyword(s):  
Numerical Simulations ◽  
Power Law ◽  
Large Scale ◽  
Laboratory Experiments ◽  
Passive Scalar ◽  
Decay Rates ◽  
Small Scale ◽  
Two Dimensional ◽  
Ekman Pumping ◽  
Viscous Boundary Layer

Laboratory experiments and numerical simulations of oscillating spin-up in a square tank have been conducted to investigate the production of small-scale vorticity near the no-slip sidewalls of the container and the formation and subsequent decay of wall-generated quasi-two-dimensional vortices. The flow is made quasi-two-dimensional by a steady background rotation, and a small sinusoidal perturbation to the background rotation leads to the periodic formation of eddies in the corners of the tank by the roll-up of vorticity generated along the sidewalls. When the oscillation period is greater than the time scale required to advect a full-grown corner vortex to approximately halfway along the sidewall, dipole structures are observed to form. These dipoles migrate away from the walls, and the interior of the tank is continually filled with new vortices. The average size of these vortices appears to be largely controlled by the initial formation mechanism. Their vorticity decays from interactions with other stronger vortices that strip off filaments of vorticity, and by Ekman pumping at the bottom of the tank. Subsequent interactions between the weaker ‘old’ vortices and the ‘young’ vortices result in the straining, and finally the destruction, of older vortices. This inhibits the formation of large-scale vortices with diameters comparable to the size of the container.The laboratory experiments revealed a k−5/3 power law of the energy spectrum for small-to-intermediate wavenumbers. Measurements of the intensity spectrum of a passive scalar were consistent with the Batchelor prediction of a k−1 power law at large wavenumbers. Two-dimensional numerical simulations, under similar conditions to those in the experiments (with weak Ekman decay), were also performed and the simultaneous presence of a k−5/3 and k−3−ζ (with 0 < ζ « 1) power spectrum is observed, with the transition occurring at the wavenumber at which vorticity is injected from the viscous boundary layer into the interior. For higher Ekman decay rates, steeper spectra are obtained for the large wavenumber range, with ζ = O(1) and proportional to the Ekman decay rate. Movies are available with the online version of the paper.

scholarly journals Condensates in rotating turbulent flows

2018 ◽  
Vol 841 ◽  
pp. 434-462 ◽  
Author(s):  
Kannabiran Seshasayanan ◽  
Alexandros Alexakis
Keyword(s):  
Numerical Simulations ◽  
Turbulent Flows ◽  
Rotation Rate ◽  
Large Scale ◽  
Two Dimensional ◽  
Control Parameters ◽  
Scaling Properties ◽  
Viscous Forces ◽  
Critical Rotation ◽  
Axis Of Rotation

Using a large number of numerical simulations we examine the steady state of rotating turbulent flows in triple periodic domains, varying the Rossby number $Ro$ (that measures the inverse rotation rate) and the Reynolds number $Re$ (that measures the strength of turbulence). The examined flows are sustained by either a helical or a non-helical Roberts force, that is invariant along the axis of rotation. The forcing acts at a wavenumber $k_{f}$ such that $k_{f}L=4$, where $2\unicode[STIX]{x03C0}L$ is the size of the domain. Different flow behaviours were obtained as the parameters are varied. Above a critical rotation rate the flow becomes quasi-two-dimensional and transfers energy to the largest scales of the system, forming large coherent structures known as condensates. We examine the behaviour of these condensates and their scaling properties close to and away from this critical rotation rate. Close to the critical rotation rate the system transitions supercritically to the condensate state, displaying a bimodal behaviour oscillating randomly between an incoherent-turbulent state and a condensate state. Away from the critical rotation rate, it is shown that two distinct mechanisms can saturate the growth of the large-scale energy. The first mechanism is due to viscous forces and is similar to the saturation mechanism observed for the inverse cascade in two-dimensional flows. The second mechanism is independent of viscosity and relies on the breaking of the two-dimensionalization condition of the rotating flow. The two mechanisms predict different scaling with respect to the control parameters of the system (Rossby and Reynolds), which are tested with the present results of the numerical simulations. A phase space diagram in the $Re,Ro$ parameter plane is sketched.

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