Wind-Driven Natural Ventilation in an Areaway-Attached Basement with a Single-Sided Opening for Residential Purposes

This paper discusses the sustainability of the areaway-attached basement concept with the attentions focused on wind-driven single-sided natural ventilation. First, numerical simulations were performed on an areaway-attached basement with a single-sided opening. Two CFD approaches: Reynolds averaged Navier-Stokes (RANS) and large-eddy simulation (LES) were used and compared with the previous experimental results of effective ventilation rate. A good agreement between the measurement and LES model was found and RANS model tends to underestimate the ventilation rates. Furthermore, Based on LES with the inflow turbulent fluctuations, the mean airflow patterns within and around the areaway-attached basement was investigated for different wind incidence angles to examine the influences of wind direction on ventilation performances.

ICCM2015: A Comparison of RANS and LES Computational Methods in Analyzing Ventilation Flow Through a Room Fitted with a Two-Sided Windcatcher

International Journal of Computational Methods ◽

10.1142/s0219876217500219 ◽

2017 ◽

Vol 14 (03) ◽

pp. 1750021 ◽

Cited By ~ 2

Author(s):

A. Niktash ◽

B. P. Huynh

Keyword(s):

Natural Ventilation ◽

Three Dimensional ◽

Navier Stokes ◽

Interior Space ◽

Eddy Simulation ◽

Large Eddy ◽

Computational Fluid Dynamics Cfd ◽

Flow Through ◽

Cfd Method ◽

A windcatcher is a structure for providing natural ventilation using wind power; it is usually fitted on the roof of a building to exhaust the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building. In this paper, the behavior of free wind flow through a three-dimensional room fitted with a centered position two-canal bottom shape windcatcher model is investigated numerically, using a commercial computational fluid dynamics (CFD) software package and LES (Large Eddy Simulation) CFD method. The results have been compared with the obtained results for the same model but using RANS (Reynolds Averaged Navier–Stokes) CFD method. The model with its surrounded space has been considered in both method. It is found that the achieved results for the model from LES method are in good agreement with RANS method’s results for the same model.

LES Applied to Ship Research

Journal of Ship Research ◽

10.5957/jsr.2015.59.4.238 ◽

2015 ◽

Vol 59 (04) ◽

pp. 238-245

Author(s):

Krishnan Mahesh ◽

Praveen Kumar ◽

Aswin Gnanaskandan ◽

Zane Nitzkorski

Keyword(s):

Navier Stokes ◽

Predictive Capability ◽

Complex Flow ◽

Flow Problems ◽

Eddy Simulation ◽

Fluid Behavior ◽

Large Eddy ◽

The Mean ◽

Physical Phenomena ◽

Numerical simulations using the Reynolds Averaged Navier-Stokes (RANS) methodology have been widely used to study fluid problems in a variety of fields including ship research. Although computationally cheap, RANS fails to predict the fluid behavior accurately in complex flow problems where the underlying physics is dominated by unsteady complex physical phenomena. This paper discusses the use of large eddy simulation (LES) to study such complex flow physics. The predictive capability of LES is demonstrated in three complex flow problems: crashback, cavitation, and hydro-acoustics, which are of particular interest to the ship community. LES results are shown to be in good agreement with experiments for the mean and root mean square values of flow quantities in all these cases.

Interpolation of LES Cloud Surfaces for Use in Direct Calculations of Entrainment and Detrainment

Monthly Weather Review ◽

10.1175/2010mwr3473.1 ◽

2011 ◽

Vol 139 (2) ◽

pp. 444-456 ◽

Cited By ~ 31

Author(s):

Jordan T. Dawe ◽

Philip H. Austin

Keyword(s):

Numerical Model ◽

Spatial Scales ◽

Grid Cell ◽

Time Step ◽

Eddy Simulation ◽

Large Eddy ◽

Temporal And Spatial ◽

Les Model ◽

Direct Calculations ◽

Abstract Direct calculations of the entrainment and detrainment of air into and out of clouds require knowledge of the relative velocity difference between the air and the cloud surface. However, a discrete numerical model grid forces the distance moved by a cloud surface over a time step to be either zero or the width of a model grid cell. Here a method for the subgrid interpolation of a cloud surface on a discrete numerical model grid is presented. This method is used to calculate entrainment and detrainment rates for a large-eddy simulation (LES) model, which are compared with rates calculated via the direct flux method of Romps. The comparison shows good agreement between the two methods as long as the model clouds are well resolved by the model grid spacing. This limitation of this technique is offset by the ability to resolve fluxes on much finer temporal and spatial scales, making it suitable for calculating entrainment and detrainment profiles for individual clouds.

Large Eddy Simulation of Round Impinging Jets With Large Stand-Off Distance

Volume 7: Fluids Engineering Systems and Technologies ◽

10.1115/imece2014-37194 ◽

2014 ◽

Author(s):

Mehrdad Shademan ◽

Vesselina Roussinova ◽

Ron Barron ◽

Ram Balachandar

Keyword(s):

Large Eddy Simulation ◽

Flow Characteristics ◽

Impinging Jet ◽

Impinging Jets ◽

Vortical Structures ◽

Nozzle Height ◽

Eddy Simulation ◽

Large Eddy ◽

The Mean ◽

Large Eddy Simulation (LES) has been carried out to study the flow of a turbulent impinging jet with large nozzle height-to-diameter ratio. The dynamic Smagorinsky model was used to simulate the subgrid-scale stresses. The jet exit Reynolds number is 28,000. The study presents a detailed evaluation of the flow characteristics of an impinging jet with nozzle height of 20 diameters above the plate. Results of the mean normalized centerline velocity and wall shear stress show good agreement with previous experiments. Analysis of the flow field shows that vortical structures generated due to the Kelvin-Helmholtz instabilities in the shear flow close to the nozzle undergo break down or merging when moving towards the plate. Unlike impinging jets with small stand-off distance where the ring-like vortices keep their interconnected shape upon reaching the plate, no sign of interconnection was observed on the plate for this large stand-off distance. A large deflection of the jet axis was observed for this type of impinging jet when compared to the cases with small nozzle height-to-diameter ratios.

LES and RANS Investigations Into Buoyancy-Affected Convection in a Rotating Cavity With a Central Axial Throughflow

Volume 3: Heat Transfer, Parts A and B ◽

10.1115/gt2006-90251 ◽

2006 ◽

Cited By ~ 5

Author(s):

Zixiang Sun ◽

Klas Lindblad ◽

John W. Chew ◽

Colin Young

Keyword(s):

Heat Transfer ◽

Tangential Velocity ◽

Navier Stokes ◽

Test Cases ◽

Test Rig ◽

Rotating Disc ◽

Eddy Simulation ◽

Rotating Cavity ◽

Large Eddy ◽

The buoyancy-affected flow in rotating disc cavities, such as occurs in compressor disc stacks, is known to be complex and difficult to predict. In the present work large eddy simulation (LES) and unsteady Reynolds-averaged Navier-Stokes (RANS) solutions are compared with other workers’ measurements from an engine representative test rig. The Smagorinsky-Lilly model was employed in the LES simulations, and the RNG k-ε turbulence model was used in the RANS modelling. Three test cases were investigated in a range of Grashof number Gr = 1.87 to 7.41×108 and buoyancy number Bo = 1.65 to 11.5. Consistent with experimental observation, strong unsteadiness was clearly observed in the results of both models, however the LES results exhibited a finer flow structure than the RANS solution. The LES model also achieved significantly better agreement with velocity and heat transfer measurements than the RANS model. Also, temperature contours obtained from the LES results have a finer structure than the tangential velocity contours. Based on the results obtained in this work, further application of LES to flows of industrial complexity is recommended.

On the Investigation of Flow around the Square Cylinder Based on Different LES Models

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.594-597.2676 ◽

2012 ◽

Vol 594-597 ◽

pp. 2676-2679

Author(s):

Zhe Liu

Keyword(s):

Flow Characteristics ◽

Turbulence Models ◽

Navier Stokes ◽

Detached Eddy Simulation ◽

Square Cylinder ◽

Rans Model ◽

Eddy Simulation ◽

Large Eddy ◽

Reynolds Averaged Navier Stokes ◽

Although the conventional Reynolds-averaged Navier–Stokes (RANS) model has been widely applied in the industrial and engineering field, it is worthwhile to study whether these models are suitable to investigate the flow filed varying with the time. With the development of turbulence models, the unsteady Reynolds-averaged Navier–Stokes (URANS) model, detached eddy simulation (DES) and large eddy simulation (LES) compensate the disadvantage of RANS model. This paper mainly presents the theory of standard LES model, LES dynamic model and wall-adapting local eddy-viscosity (WALE) LES model. And the square cylinder is selected as the research target to study the flow characteristics around it at Reynolds number 13,000. The influence of different LES models on the flow field around the square cylinder is compared.

Comparison of Partially Averaged Navier–Stokes and Large-Eddy Simulations of the Flow Around a Cuboid Influenced by Crosswind

Journal of Fluids Engineering ◽

10.1115/1.4007363 ◽

2012 ◽

Vol 134 (10) ◽

Cited By ~ 8

Author(s):

Siniša Krajnović ◽

Per Ringqvist ◽

Branislav Basara

Keyword(s):

Experimental Data ◽

Large Eddy Simulation ◽

Large Eddy Simulations ◽

Navier Stokes ◽

Eddy Simulation ◽

Large Eddy ◽

Better Than ◽

Good Agreement ◽

Near Wall

The paper presents a partially averaged Navier–Stokes (PANS) simulation of the flow around a cuboid influenced by crosswind. The results of the PANS prediction are validated against experimental data and results of a large-eddy simulation (LES) made using the same numerical conditions as PANS. The PANS shows good agreement with the experimental data. The prediction of PANS was found to be better than that of the LES in flow regions where simulations suffered from poor near-wall resolution.

Predicting Unsteady Loads in Marine Propulsor Crashback Using Large Eddy Simulation

International Journal of Rotating Machinery ◽

10.1155/2012/543096 ◽

2012 ◽

Vol 2012 ◽

pp. 1-12 ◽

Cited By ~ 3

Author(s):

Hyunchul Jang ◽

Aman Verma ◽

Krishnan Mahesh

Keyword(s):

Large Eddy Simulation ◽

Reverse Flow ◽

Reverse Direction ◽

Unsteady Forces ◽

Eddy Simulation ◽

Large Eddy ◽

The Mean ◽

Submarine Hull ◽

Marine Propulsor ◽

Propulsor crashback is an off-design operating condition where a propulsor rotates in the reverse direction to yield negative thrust. Crashback is characterized by the interaction of the free stream with the reverse flow generated by propulsor rotation. This causes a highly unsteady vortex ring which leads to flow separation and unsteady forces and moments on the blades. Large eddy simulation (LES) is performed for marine propulsors in crashback for various configurations and advance ratios and validated against experiments. The predictive capability of LES as a tool for propulsor crashback is demonstrated on an open propulsor, open propulsor with a submarine hull, and ducted propulsor with and without stator blades. LES is in good agreement with experiments for the mean and RMS levels, and spectra of the unsteady loads on the propulsors.

Hybrid LES Approach for Practical Turbomachinery Flows—Part II: Further Applications

Journal of Turbomachinery ◽

10.1115/1.4003062 ◽

2011 ◽

Vol 134 (2) ◽

Cited By ~ 10

Author(s):

Paul Tucker ◽

Simon Eastwood ◽

Christian Klostermeier ◽

Hao Xia ◽

Prasun Ray ◽

...

Keyword(s):

Navier Stokes ◽

Jet Flows ◽

Hybrid Strategy ◽

Eddy Simulation ◽

Wall Flows ◽

Large Eddy ◽

Blade Section ◽

Transition Modeling ◽

Fan Blade ◽

A hybrid large eddy simulation (LES) related technique is used to explore some key turbomachinery relevant flows. Near wall Reynolds-averaged Navier-Stokes (RANS) modeling is used to cover over especially small scales, the LES resolution of which is generally intractable with current computational power. Away from walls, large eddy type simulation is used but with no LES model (numerical LES (NLES)). Linking of the two model zones through a Hamilton–Jacobi equation is explored. The hybrid strategy is used to predict turbine and compressor end wall flows, flow around a fan blade section, jet flows, and a cutback trailing edge. Also, application of NLES to the flow in an idealized high pressure compressor drum cavity is considered. Generally, encouraging results are found. However, challenges remain, especially for flows where transition modeling is important.

Large Eddy Simulation of Aerodynamic Forces on a Bridge Pylon

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.1578 ◽

2011 ◽

Vol 243-249 ◽

pp. 1578-1582

Author(s):

Xu Yong Ying ◽

Fu You Xu ◽

Zhe Zhang ◽

Yong Gang Tan

Keyword(s):

Large Eddy Simulation ◽

Bluff Body ◽

Stokes Equations ◽

Three Dimensional ◽

Wind Tunnel Test ◽

Navier Stokes ◽

Aerodynamic Forces ◽

Eddy Simulation ◽

Large Eddy ◽

In this study, aerodynamic forces on a bridge pylon are investigated by three-dimensional computational fluid dynamics using Large eddy simulation (LES) technology. The main objective is to identify the wind load parameters of the pylon and examine the accuracy of LES model applied to the bluff-body flows. The numerical results were compared with the available wind tunnel test results. Also, a comparison between using LES and Reynolds averaged Navier-Stokes equations with the RNG model have been made. It is found that the LES model competes the RNG model in accuracy for predictions of aerodynamic forces on the pylon.