scholarly journals Loosely coupled and coupled solution methods for the RANS equations and a one-equation turbulence model

2021 ◽  
pp. 105186
Author(s):  
Stefan Langer ◽  
Guillermo Suárez
Keyword(s):  
Turbulence Model ◽  
Rans Equations ◽  
Loosely Coupled ◽  
Solution Methods ◽  
Coupled Solution

Development and validation of an incompressible Navier-Stokes solver including convective heat transfer

2015 ◽  
Vol 25 (4) ◽  
pp. 861-886 ◽  
Author(s):  
Konstantinos Stokos ◽  
Socrates Vrahliotis ◽  
Theodora Pappou ◽  
Sokrates Tsangaris
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Laminar Flows ◽  
Navier Stokes ◽  
Content Type ◽  
Strongly Coupled ◽  
Loosely Coupled ◽  
Wide Range ◽  
Coupled Solution

Purpose – The purpose of this paper is to present a numerical method for the simulation of steady and unsteady incompressible laminar flows, including convective heat transfer. Design/methodology/approach – A node centered, finite volume discretization technique is applied on hybrid meshes. The developed solver, is based on the artificial compressibility approach. Findings – A sufficient number of representative test cases have been examined for the validation of this numerical solver. A wide range of the various dimensionless parameters were applied for different working fluids, in order to estimate the general applicability of our solver. The obtained results agree well with those published by other researchers. The strongly coupled solution of the governing equations showed superiority compared to the loosely coupled solution as inviscid effects increase. Practical implications – Convective heat transfer is dominant in a wide variety of practical engineering problems, such as cooling of electronic chips, design of heat exchangers and fire simulation and suspension in tunnels. Originality/value – A comparison between the strongly coupled solution and the loosely coupled solution of the Navier-Stokes and energy equations is presented. A robust upwind scheme based on Roe’s approximate Riemann solver is proposed.

Tall building influence on city wind pattern

2018 ◽  
Vol 29 (10) ◽  
pp. 1850086
Author(s):  
M. S. Almeida ◽  
A. D. Araújo ◽  
M. P. Almeida
Keyword(s):  
Population Growth ◽  
Numerical Simulations ◽  
Turbulence Model ◽  
Natural Ventilation ◽  
Tall Buildings ◽  
Navier Stokes ◽  
Urban Centers ◽  
Wind Pattern ◽  
Rans Equations ◽  
Weak Wind

The population growth in big urban centers generates the necessity for tall buildings. This phenomenon happens also in tourist regions where it is necessary to host many people. However, locations with high buildings interfere with the flow of the wind and can affect the comfort and safety of pedestrians at street level. Tall buildings barrier reduces the natural ventilation in regions far from the beach. This work presents the results concerning the effects created by tall buildings on Mucuripe beach, Fortaleza, Brazil. We performed numerical simulations to verify the wind interference with buildings in an area of [Formula: see text][Formula: see text]m2, using the OpenFOAM toolbox, to solve the Reynolds Averaged Navier–Stokes (RANS) equations with the [Formula: see text]–[Formula: see text] turbulence model. The results showed how the obstacles alter the airflow. From them, one can identify the regions with reduced safety and pedestrian comfort, and also the weak wind zone created by the downstream of the constructions for the different wind directions that are locally observed.

A comparative numerical study of four turbulence models for the prediction of horizontal axis wind turbine flow

2010 ◽  
Vol 224 (9) ◽  
pp. 1973-1979 ◽  
Author(s):  
N S Tachos ◽  
A E Filios ◽  
D P Margaris
Keyword(s):  
Wind Turbine ◽  
Turbulence Model ◽  
Numerical Study ◽  
Free Field ◽  
Turbulence Models ◽  
Horizontal Axis ◽  
Wind Condition ◽  
Computational Domain ◽  
Horizontal Axis Wind Turbine ◽  
Rans Equations

The analysis of the near and far flow fields of an experimental National Renewable Energy Laboratory (NREL) rotor, which has been used as the reference rotor for the Viscous and Aeroelastic Effects on Wind Turbine Blades (VISCEL) research program of the European Union, is described. The horizontal axis wind turbine (HAWT) flow is obtained by solving the steady-state Reynolds-averaged Navier—Stokes (RANS) equations, which are combined with one of four turbulence models (Spalart—Allmaras, k—∊, k—∊ renormalization group, and k—ω shear stress transport (SST)) aiming at validation of these models through a comparison of the predictions and the free field experimental measurements for the selected rotor. The computational domain is composed of 4.2×106 cells merged in a structured way, taking care of refinement of the grid near the rotor blade in order to enclose the boundary layer approach. The constant wind condition 7.2 m/s, which is the velocity of the selected experimental data, is considered in all calculations, and only the turbulence model is altered. It is confirmed that it is possible to analyse a HAWT rotor flow field with the RANS equations and that there is good agreement with experimental results, especially when they are combined with the k—ω SST turbulence model.

Application of a Fast Loosely Coupled Fluid/Solid Heat Transfer Method to the Transient Analysis of Low-Pressure-Turbine Disk Cavities

2013 ◽  
Author(s):  
Arnau Altuna ◽  
Jose M. Chaquet ◽  
Roque Corral ◽  
Fernando Gisbert ◽  
Guillermo Pastor
Keyword(s):  
Graphics Processing Units ◽  
Axisymmetric Flow ◽  
Low Pressure ◽  
Loosely Coupled ◽  
Low Pressure Turbine ◽  
Transfer Method ◽  
Turbine Design ◽  
Graphics Processing ◽  
Coupled Solution ◽  
Fully Coupled

A transient aero-thermal analysis of the disk cavities of an aero-engine LPT (Low Pressure Turbine) is presented. The full simulation includes a 2D thermal model of the solid parts combined with an axisymmetric flow model of six separate cavities interconnected through inlet and outlet boundaries. Computing elapsed time is significantly reduced by using a cluster of GPUs (Graphics Processing Units) making this approach compatible with turbine design time-frames. The problem of flow reversal that takes place in some of the cavity boundaries along the transient flight cycle is addressed in detail. The fully coupled numerical solution is validated against engine data and compared as well against an uncoupled simulation. It is shown that the coupled solution outperforms the uncoupled one in terms of accuracy, since it removes some hypotheses inherent to the uncoupled approach. It is believed that this is the first time that GPUs have been used to solve a fully coupled fluid/solid thermal problem of industrial interest for the gas turbine community.

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