scholarly journals Effects of Inflow Condition on RANS and LES Predictions of the Flow around a High-Rise Building

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 233
Author(s):  
Giulio Vita ◽  
Simone Salvadori ◽  
Daniela Anna Misul ◽  
Hassan Hemida
Keyword(s):  
Navier Stokes ◽  
Ambient Conditions ◽  
Engineering Applications ◽  
Building Model ◽  
High Rise ◽  
High Rise Building ◽  
Eddy Simulation ◽  
Turbulent Inflow ◽  
Flow Features ◽  
Inflow Condition

An increasing number of engineering applications require accurate predictions of the flow around buildings to guarantee performance and safety. This paper investigates the effects of variations in the turbulent inflow, as predicted in different numerical simulations, on the flow pattern prediction around buildings, compared to wind tunnel tests. Turbulence characteristics were assessed at several locations around a model square high-rise building, namely, above the roof region, at the pedestrian level, and in the wake. Both Reynolds-averaged Navier–Stokes (RANS, where turbulence is fully modelled) equations and large-eddy simulation (LES, where turbulence is partially resolved) were used to model an experimental setup providing validation for the roof region. The performances of both techniques were compared in ability to predict the flow features. It was found that RANS provides reliable results in regions of the flow heavily influenced by the building model, and it is unreliable where the flow is influenced by ambient conditions. In contrast, LES is generally reliable, provided that a suitable turbulent inflow is included in the simulation. RANS also benefits when a turbulent inflow is provided in simulations. In general, LES should be the methodology of choice if engineering applications are involved with the highly separated and turbulent flow features around the building, and RANS provides reliable information when regions of high wind speed and low turbulence are investigated.

Large-eddy simulation evaluation of wind loads on a high-rise building based on the multiscale synthetic eddy method

2018 ◽  
Vol 22 (4) ◽  
pp. 997-1006 ◽  
Author(s):  
Yin Luo ◽  
Hongjun Liu ◽  
Huili Xue ◽  
Kun Lin
Keyword(s):  
Large Eddy Simulation ◽  
Wind Pressure ◽  
Turbulent Structures ◽  
Building Model ◽  
High Rise ◽  
High Rise Building ◽  
Eddy Simulation ◽  
Simulation Evaluation ◽  
Large Eddy ◽  
Inflow Turbulence

In this study, the multiscale synthetic eddy method, which can establish coherent turbulent structures and satisfy predefined turbulent statistical and spectral properties, is employed to generate the inflow turbulence for large-eddy simulation of a high-rise building. The recycling method of Lund and synthetic eddy method is also applied to assess the suitability of multiscale synthetic eddy method. The wind pressure at each mesh face centre on the surface of the high-rise building model is exported in the simulation to determine the wind-induced aerodynamic loads. Compared with the synthetic eddy method, the multiscale synthetic eddy method result is in higher agreement with that of the recycling method of Lund in terms of the wind pressure distribution, wind load characteristic and external flow field of the high-rise building.

Earthquake induced floor accelerations on a high-rise building: Scale model tests on a shaking table

2021 ◽  
Author(s):  
Fabio Rizzo ◽  
Alessandro Pagliaroli ◽  
Giuseppe Maddaloni ◽  
Antonio Occhiuzzi ◽  
Andrea Prota
Keyword(s):  
Soil Structure ◽  
Shaking Table ◽  
Soil Structure Interaction ◽  
Scale Model ◽  
Structural Elements ◽  
Shaking Table Tests ◽  
Building Model ◽  
High Rise ◽  
High Rise Building ◽  
Story Building

<p>The paper discusses results of shaking table tests on an in-scale high-rise building model. The purpose was to calibrate a dynamic numerical model for multi-hazard analyses to investigate the effects of floor acceleration. Accelerations, because of vibration of non-structural elements, affect both the comfort and safety of people. The research investigates the acceleration effects of both seismic and wind forces on an aeroelastic in-scale model of a multi-story building. The paper discusses the first phase of experiments and gives results of floor accelerations induced by several different base seismic impulses. Structural analyses were first performed on the full-scale prototype to take soil-structure interaction into account. Subsequently the scale model was designed through aeroelastic scale laws. Shaking table experiments were then carried out under different base accelerations. The response of the model and, in particular, amplification of effects from base to top are discussed.</p>

Numerical Investigation of Energy Saving Device Effects on Ships With Propeller-Hull Interactions

2018 ◽  
Author(s):  
Ravi Chaithanya Mysa ◽  
Le Quang Tuyen ◽  
Ma Shengwei ◽  
Vinh-Tan Nguyen
Keyword(s):  
Energy Saving ◽  
Full Scale ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Propulsion Efficiency ◽  
Operational Conditions ◽  
Ship Resistance ◽  
The Past ◽  
Eddy Simulation ◽  
Flow Features

Energy saving devices (ESD) such as propeller ducts, pre-swirl stators, pre-nozzles, etc have been explored as a more economic and reliable approach to reduce energy consumption for both in-operation and newly design ships over the past decades. Those energy saving devices work in the principle of reducing ship resistance and improving propulsion efficiency as well as hull-propeller interactions. Potential saving from various types of ESD have been reported in literature from the range of 3–9% [1] for propulsion efficiency dependent on different measures. Deployment of those devices on actual full-scale ships has been limited over the past years. One of the key obstacles in application of ESD is the lack of confidence in measuring its efficiency on full-scale ships in actual operational conditions. Advances in computational fluid dynamics (CFD) has provided an alternative approach from model scale test to better understand uncertainties in prediction of ESD efficiency in full-scale ship operations [Shin et al, 2013]. In this work a high fidelity CFD model is presented for investigation effects of pre-nozzles on propulsion efficiency and ship resistance. The model is based on the Reynolds Average Navier-Stokes (RANS) solver with different turbulent models including a hybrid detached eddy simulation (DES) approach for predictions of complex near body flow features as well as in the wake regions from hull and propeller. The model is validated with model test for both towing and self-propulsion conditions. Finally a study of pre-nozzle effects on propeller efficiency as well as hull-propeller interaction is presented and compared with available experimental data (Tokyo 2015 Workshop). The current work constitutes a fundamental approach towards designing more efficient ESD for a specific hull form and propeller.

scholarly journals Wind tunnel tests of aerodynamic interference of the high-rise building and its nearest city surroundings

2013 ◽  
Vol 12 (2) ◽  
pp. 079-086
Author(s):  
Grzegorz Bosak
Keyword(s):  
Wind Tunnel ◽  
Building Design ◽  
Wind Pressure ◽  
Horizontal Wind ◽  
Wind Tunnel Tests ◽  
Wind Action ◽  
Building Model ◽  
High Rise ◽  
High Rise Building ◽  
Aerodynamic Interference

The paper summarizes the results of wind tunnel tests of the influence of aerodynamic interference on wind action of a high-rise building design in Warsaw. Measurements were accomplished in Wind Engineering Laboratory of Cracow University of Technology. Wind pressures on external surfaces of the building model were acquired in two different situations. Firstly, only the building model was placed in the tunnel working section, secondly, the building model with the nearest surroundings was taken under consideration. A study of the character of wind action differences caused by the nearest surroundings of the building was the main aim of the paper. Wind pressure coefficients on the external building surfaces and the difference of horizontal wind action on full scale were compared.

Large Eddy Simulation of the Flow Around a Diffuser-Equipped Bluff Body in Ground Effect

2011 ◽  
Author(s):  
Lara Schembri Puglisevich ◽  
Gary Page
Keyword(s):  
Large Eddy Simulation ◽  
Bluff Body ◽  
Vortex Formation ◽  
Ground Effect ◽  
Vortical Flow ◽  
Navier Stokes ◽  
Flow Structures ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Features

Unsteady Large Eddy Simulation (LES) is carried out for the flow around a bluff body equipped with an underbody rear diffuser in close proximity to the ground, representing an automotive diffuser. The goal is to demonstrate the ability of LES to model underbody vortical flow features at experimental Reynolds numbers (1.01 × 106 based on model height and incoming velocity). The scope of the time-dependent simulations is not to improve on Reynolds-Averaged Navier Stokes (RANS), but to give further insight into vortex formation and progression, allowing better understanding of the flow, hence allowing more control. Vortical flow structures in the diffuser region, along the sides and top surface of the bluff body are successfully modelled. Differences between instantaneous and time-averaged flow structures are presented and explained. Comparisons to pressure measurements from wind tunnel experiments on an identical bluff body model shows a good level of agreement.

scholarly journals Multizone modelling of a hybrid ventilated high-rise building based on full-scale measurements for predictive control

2019 ◽  
Vol 29 (4) ◽  
pp. 496-507 ◽  
Author(s):  
Dahai Qi ◽  
Jun Cheng ◽  
Ali Katal ◽  
Liangzhu (Leon) Wang ◽  
Andreas Athienitis
Keyword(s):  
Predictive Control ◽  
Simulation Models ◽  
Full Scale ◽  
Ambient Conditions ◽  
High Rise ◽  
High Rise Building ◽  
Building Simulations ◽  
On Line ◽  
Hybrid Ventilation ◽  
And Performance

Hybrid ventilation is an effective approach to reduce cooling energy consumption by combining natural and mechanical ventilation. Previous studies of full-scale whole-building measurements of high-rise hybrid ventilation are quite limited due to the complexities of buildings and variable ambient conditions. As a result, validated and accurate whole-building simulations of hybrid ventilation often cannot be found in the literature. This paper reports a series of full-scale measurements of hybrid ventilation in a 17-storey high-rise building and associated whole-building simulations by 15-zone detailed and a 5-zone simplified multizone models. The paper is one of the first studies of using multizone models and real-world full-scale data and sharing key operational and performance experience and case studies of high-rise hybrid ventilation. Both the test data and the validated simulation models can be used for the comparison and validation of simulation models. The 5-zone simplified model developed from this study was able to model such a complex high-rise building by only a few zones, making possible the on-line model predictive control of a high-rise building. This was illustrated in this paper by an example of optimizing the uniformity of the hybrid ventilation on different floors by modifying inlet areas.

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