Asiri Weerasuriya

The Hong Kong Metropolitan University · School of Science and Technology

Natural ventilation is particularly important for residential high-rise buildings as it maintains indoor human comfort without incurring the energy demands that air conditioning does. To improve a building's natural ventilation, it is essential to develop models to understand the relationship between wind flow characteristics and the building's des...

Cross-ventilation is the most effective mode of wind-driven natural ventilation but completely depends on the external openings and internal layout. This study investigates how openings affect cross-ventilation of a generic four-wall space using Computational Fluid Dynamics (CFD) simulation. The building has one to four external openings of two dif...

In conventional modeling of air pollution dispersion, pollutants are treated as passive scalars or inert species even though most of them are chemically reactive [1]. Chemical reactions contribute to pollutant dispersion via the generation and depletion of pollutants, in addition to other two mechanisms: advection and turbulent diffusion. This stud...

The provisions in wind loading standards routinely overlook the influence of nearby small-size objects on wind loads of low-rise buildings. One such object is boundary walls that significantly modify the surrounding wind field thereby affecting the wind loading of low-rise buildings. To investigate this phenomenon, four low-rise, gable-roofed build...

This study used explainable machine learning (XML), a new branch of Machine Learning (ML), to elucidate how ML models make predictions. Three tree-based regression models, Decision Tree (DT), Random Forest (RF), and Extreme Gradient Boost (XGB), were used to predict the normalized mean (C p,mean), fluctuating (C p,rms), minimum (C p,min), and maxim...

Poorly designed internal walls deter natural ventilation of buildings, causing poor indoor air quality and exorbitant energy costs when mechanical ventilation systems are used. Although one can design internal walls with minimum adverse effects on natural ventilation by controlling height, width, location, and porosity of internal walls, less resea...

This paper distills the serial work of Li et al., 2020a, Li et al., 2021, Li et al., 2022a, Li et al., 2022b, Li et al., 2022c, Li et al., 2023a, Li et al., 2023b into a practice guide for the Dynamic Mode Decomposition (DMD) with a particular emphasis on the quick learning and adaptation of the technique from a wind engineering perspective. The gu...

Trees are often planted next to buildings for shade, evapotranspiration cooling, and as windbreaks. As windbreaks, trees slow down wind, consequently reducing the natural ventilation of the buildings that they shield. This reduction in natural ventilation has such parameters as the trees’ locations, geometry (height (h), width (w), thickness (t)),...

This serial work presents a linear-time-invariance (LTI) notion to the Koopman analysis, finding consistent and physically meaningful Koopman modes and addressing a long-standing problem of fluid mechanics: deterministically relating the fluid excitations and corresponding structure reactions. Part 1 (Li et al., Phys. Fluids, vol. 34, no. 12, p. 12...

Trees planted in rows have been used as shelterbelts to protect crops from strong winds. Similarly, trees can be used as windbreaks to reduce wind loading on buildings to protect them from wind damages. This hypothesis was tested in this study by conducting a series of wind tunnel tests using scaled-down models of a gable-roofed, low-rise building,...

This study investigated the interpersonal droplet transmission between a healthy and an infected person in a deep and narrow street canyon using Computational Fluid Dynamics (CFD) simulation. The CFD simulations modelled various droplet sizes ( D p ), background wind speeds ( U ref ), relative humidity (RH), and social distances ( D ) to estimate t...

This study investigated interpersonal droplet transmission between a healthy and an infected person in a two-dimensional (2D) street canyon using Computational Fluid Dynamics (CFD) simulation. The CFD simulation modeled four droplet sizes (Dp), two ambient wind speeds (Uref), three relative humidity (RH) levels, and four social distances (D) to est...

Scientific research and engineering practice often require the modeling and decomposition of nonlinear systems. The dynamic mode decomposition (DMD) is a novel Koopman-based technique that effectively dissects high-dimensional nonlinear systems into periodically distinct constituents on reduced-order subspaces. As a novel mathematical hatchling, th...

Purpose Beyond a mandated use, rationales behind executive choice to accept or reject building information modelling (BIM) are ambiguous. BIM acceptance is complex for organisations, and existing decision-making models are impractical to make realistic choices. A practical solution must assist a holistic reflection of internal and external BIM succ...

The present work extends the parametric investigation on the sampling nuances of dynamic mode decomposition (DMD) under Koopman analysis. Through turbulent wakes, the study corroborated the generality of universal convergence states for all DMD implementations. It discovered implications of sampling range and resolution—determinants of spectral dis...

This work presents a new architecture of the Koopman operatory theory called the Koopman Linearly-Time-Invariant (Koopman-LTI) analysis. The Koopman-LTI is formulated to explain fluid-structure interactions by providing constitutive and phenomenological relationships between fluid excitation and structural response. A demonstrative rendering implem...

This work delineates a new architecture of the Koopman operatory theory called the Koopman Linearly-Time-Invariant (Koopman-LTI) analysis. The Koopman-LTI is formulated to explain fluid-structure interactions by providing a constitutive relationship between fluid excitation and structural pressure response. Results from a demonstrative rendering on...

In this work, we introduce a novel data-driven formulation, the Koopman-Linearly Time-Invariant (Koopman-LTI) analysis, for analyzing Fluid-Structure Interactions (FSI). An implementation of the Koopman-LTI on a subcritical free-shear flow over a prism at Re = 22 000 corroborated a configuration-wise universal Koopman system, which approximated the...

Scientific research and engineering practice often require the modeling and decomposition of nonlinear systems. The Dynamic Mode Decomposition (DMD) is a novel Koopman-based technique that effectively dissects high-dimensional nonlinear systems into periodically distinct constituents on reduced-order subspaces. As a novel mathematical hatchling, th...

This serial effort investigates the nuances in the sampling of the Dynamic Mode Decomposition (DMD) with an engineering-oriented emphasis. In Part I, the parametric study established the convergence of sampling range and resolution. In this Part II, we examined the effects of the input variable, truncation, and data interpolation on the integrity a...

Traditional methods of pressure measurement of buildings are costly and time-consuming. As an alternative to the traditional methods, this study developed a fast and computationally economical machine learning-based model to predict surface-averaged external pressure coefficients of a building with an unconventional configuration using three tree-b...

Optimization algorithms and decision-making techniques are major components of multi-objective optimization. This study evaluated the performance of population-based metaheuristic algorithms and decision-making techniques in optimizing an unconventional building design – a lift-up design – to maximize the areas with wind and thermal comfort in a ‘h...

Single-sided and cross- ventilation of a cube-shaped building at various incident wind directions were stimulated using computational fluid dynamics (CFD). The simulation used either the Reynolds-averaged Navier-Stokes (RANS) equations in conjunction with a 2-equation turbulence model (Standard k-ε model (SKT), Realizable k-ε model (RLZ), or Renorm...

Wind tunnel tests and computational fluid dynamics (CFD) simulations remain the main modeling techniques in wind engineering despite being expensive, time-consuming, and requiring special facilities and expert knowledge. There is a clear need for a fast, accurate, but, at the same time, computationally economical substitute. This study proposes a G...

Topographical features alter the trajectory of wind on the horizontal and vertical planes by creating yaw and pitch angles of wind. Near mountains, topography-induced pitch and yaw angles are confined to the lower part of the atmospheric boundary layer and have considerable magnitudes, thus they should be taken into consideration in wind engineerin...

Pedestrian wind comfort near a 400 m super-tall building in high and low ambient wind speeds, referred to as Windy and Calm climates, is evaluated by conducting computational fluid dynamics (CFD) simulations. The super-tall building has 15 different configurations and is located at the center of 50 m medium-rise buildings in an urban-like setting....

Unconventional configurations of tall buildings are noticeably different from their counterpart of traditional building designs but nevertheless, the unconventional configurations have often been adopted for tall buildings without their impact on the pedestrian-level wind environment (PLWE) fully understood. To fill the existing knowledge gap, this...

A novel holistic framework was established using Building Information Modelling (BIM) to estimate accurately the potential of natural ventilation of residential high-rise buildings. This framework integrates Computational Fluid Dynamics (CFD) simulation, multi-zone-air-flow modelling, and Building Energy Simulation (BES) to calculate ventilation ra...

Vehicle instabilities are increased in high winds threatening the safety of vehicle and passengers ultimately causing road accidents. In this study, three types of vehicle instabilities: rollover, sideslip, and rotation of five vehicles: a passenger car, a large van, a coach, a tractor and trailer, and an articulated lorry were evaluated using a si...

This study proposes an ANN-based surrogated model as an alternative test technique to wind tunnel test and computational fluid dynamic (CFD) simulations to assess pedestrian-level wind (PLW) environments. The surrogate model was developed using wind speed data obtained from CFD simulations of 150 lift-up buildings. The proposed surrogate model succ...

Lift-up buildings are advantageous in improving the wind circulation in a congested and compact city. However, the wind conditions in the void underneath a lift-up building, also known as the lift-up area, are vital for wind comfort of occupants of lift-up buildings. This study tested 28 lift-up buildings in a boundary layer wind tunnel to assess t...

This paper presents a novel and cost-effective method to replicate modified pedestrian level wind (PLW) fields in twisted winds using a conventional wind profile with similar wind speeds and turbulent intensities. The novel method, namely the Equivalent Wind Incidence Angle (ϕEq) method was developed using data of PLW fields near five isolated buil...

The influence of twisted wind flows on the pedestrian-level wind (PLW) field of an urban area was evaluated by testing a typical urban site (Tsuen Wan, Hong Kong) in a boundary layer wind tunnel. Four twisted wind profiles with different magnitudes and directions of yaw angles were employed to investigate variations in wind speed with the propertie...

Colombo is rapidly developing as a major business centre in the South Asia region. As a result, the city is transforming its urban environment at a great rate of growing numbers in high-rise buildings and the population. The construction of high-rise buildings would induce two types of wind nuisance: high wind speed and low wind speed those are not...

Modern megacities are teeming with closely-spaced tall buildings, which limit air circulation at the pedestrian level. The resultant lack of air circulation creates poorly ventilated areas with accumulated air pollutants and thermal discomfort in the summer. To improve air circulation at the pedestrian level, buildings may be designed to have a ‘li...

The influence of twisted wind flows on pedestrian-level wind environments was evaluated by using two twisted wind profiles (TWP) in a boundary layer wind tunnel. Simulated wind profiles had maximum yaw angles of 13 and 22 to represent 'high' and 'extreme' wind twist conditions, respectively. Five buildings with the aspect ratio (Height: Width) of 4...

The influence of twisted wind flows on urban wind environments have been accounted via empirical correction methods in Air Ventilation Assessment (AVA) rather than directly employing twisted wind profiles in AVA tests. As a result, the influences of twisted wind profiles and accuracy of correction methods on the outcomes of an AVA are unknowns. The...

In both structural and environmental wind engineering, the vertical variation of wind direction is important as it impacts both the torsional response of the high-rise building and the pedestrian level wind environment. In order to systematically investigate the vertical variation of wind directions (i.e., the so-called 'twist effect') induced by h...

Though hilly topography influences both wind speeds and directions aloft, only the influence on wind speeds, i.e. the speed-up effect, has been thoroughly investigated. Due to the importance of a model showing the spatial variations of wind directions above hilly terrains, it is worthwhile to systematically assess the applicability and limitations...

Wind load calculations are done for a medium-rise building with 48 m height locates in an urban area of Sri Lanka. Five different international wind loading standards were selected to calculate wind loads according to prevailing conditions in Sri Lanka. Available 3 second gust wind speed is converted in to mean hourly wind speed and 10 minutes aver...

This paper describes the use of decision tree method to predict thermal performance of several roof systems under different climate conditions. The decision tree method is a data mining technique which has competitive advantages overother methods such as simple and clear procedure, easy to understand without having rigorous mathematical and compu...

A high-rise building of height – 183 m was employed to evaluate similarities and differences of wind load calculations done by using five major wind codes and standards. Evaluation was done in both ultimate and serviceability limit conditions. Member forces in columns, and beams, compressive stress in shear walls and support reactions obtained from...

Significant improvements of computer resources in recent past years allow to use computational fluid dynamics (CFD) methods as an alternative test method for wind tunnel tests in various wind engineering aspects. However the accuracy of CFD simulation mainly depends on careful setup of three main components of a CFD simulation, which are domain siz...

Since the mean wind profile in the tropical cyclone boundary layer is important in both the fields of meteorology and wind engineering, the wind measurements taken during the passages of several tropical cyclones or typhoons in Hong Kong by the wind-profilers and the Doppler Sonic Detection And Ranging (SODAR) have been utilized to calculate both t...