Salim M. Salim

• PhD CEng MIMechE
• Professor (Associate) at Swansea University

Prediction accuracy of pollutant dispersion within an urban street canyon of width to height ratio W/H=1 is examined using two steady-state Reynolds-averaged Navier-Stokes (RANS) turbulence closure models, the standard k-[epsilon] and Reynolds Stress Model (RSM), and Large Eddy Simulation (LES) coupled with the advection-diffusion method for specie...

Previous CFD studies on pollution dispersion problems have largely centred on employing Reynolds-Averaged Navier-Stokes (RANS) turbulence closure schemes, which have often been reported to overpredict pollutant concentration levels in comparison to wind tunnel measurement data. In addition, the majority of experimental and numerical investigations...

The performance of three different CFD numerical approaches, namely RANS, URANS and LES are evaluated to determine their suitability in the prediction of airflow and pollutant dispersion in urban street canyons. Numerical results are evaluated against wind tunnel experimental data available from an online database (www.codasc.de). LES was observed...

A strategy for dealing with turbulent flows over a two dimensional surface mounted obstacle using the wall y+ as guidance in selecting the appropriate grid configuration and corresponding turbulence models are investigated using Fluent. The CFD results were compared with experimental data from Zeidan’s Turbulent Shear Recovery behind Obstacles on S...

This project establishes a strategy of accurately modeling rotating annular flow of drilling fluid to improve the numerical predication of pressure loss in an annulus. Pressure loss is vital within several engineering applications from HVAC design to oil & gas drilling. By being able to accurately predict this through numerical methods it creates t...

The aim of this paper is to numerically investigate Vibration-Based Leak Detection (VBLD) method in pipeline systems based on Fluid–Structure Interaction (FSI) analysis to predict leakages. In previous investigations, laboratory tests were widely used to study the VBLD technique in small-diameter water loop system pipes. The current project uses An...

This study presents the use of the wall y+ approach as a form of guidance for reliable selection of mesh and turbulence models in bent pipe flow investigations. The research builds on previous studies recommended by Salim et al.[1]–[3] for using the wall y+ approach to balance between the computational cost and time. This method is proposed as an e...

Investigation on Flow Induced Vibration (FIV) in pipes is relatively new. Previous publications focused on characterizing the influences of geometric and material properties of a straight pipe. The current study investigates the influence of the curvature radius ratio in a 90-degree pipe elbow for ratios (Rc/D = 1.5, 2, 2.5, 3 and 3.5). Reynolds St...

Flow in 90-degree pipe elbow is investigated in CFD using different turbulence approaches. The present numerical results are compared against both experimental data (Sudo et al., 1998) and numerical simulations (Kim et al., 2014) for validation. The results indicate that RSM predicts the flow regime sufficiently accurate.

Over the years, the reliance on CFD to investigate air flow and pollutant dispersion has increased significantly and the majority of these studies have employed Steady Wind Boundary Conditions (SWBC) at the inlet of the computational domain. In reality, wind fluctuates both spatially and temporally and the numerical simulations do not accurately re...

This paper reports on the validation study of a commercial computational fluid dynamics program, ANSYS FLUENT v14. The purpose of the study was to determine the best turbulent model that can reproduce appropriately the wind flow field of turbulent flow in street canyon under different thermal atmospheric condition. Standard k-ε (SKE) and Large Eddy...

This paper reports on the model sensitivity analysis of a commercial computational fluid dynamics program, ANSYS FLUENT v14. The purpose of the analysis was to determine the appropriate modeling settings for numerical model of the case study. A full scale of a simplified urban street canyon was modelled and the turbulent flow was calculated using L...

Fluid-structure interactions for a single tree and a pair of trees with varying spacing subjected to gentle breeze and storm wind conditions were evaluated using Computational Fluid Dynamics (CFD). The generated velocity and pressure fields are then analysed using Finite Element Analysis (FEA) to determine the likelihood of tree damage due to the a...

Numerical simulations based on Computational Fluid Dynamics (CFD) are performed to investigate the fluid-structure interaction of trees subjected to wind loads. Pressure and velocity fields including mechanical effects on tree trunks are compared between gentle breeze and severe tropical storm conditions and it is observed that tree damage is likel...

Fluctuating Wind Boundary Condition (FWBC) is compared against a Steady Wind Boundary Condition (SWBC) to determine their suitability in the investigation of air flow and pollutant dispersion processes in urban street canyons. Numerical simulations are performed using Large Eddy Simulation (LES) and it is observed that a FWBC inlet profile produces...

Numerical studies were conducted to envisage the wind flow structures in street canyon for differential heated wall and Richardson numbers. Two-equation turbulence models, namely the Standard k-ε, Renormalization Group (RNG) k-ε and Realizable k-ε were applied to investigate the effect of flow structure on pollutant dispersion in a square street ca...

As a result of rapid urbanization in numerous cities around the world, the demand for transportation has increased rapidly, resulting in emission of high levels of exhaust pollutants into the atmosphere. This is a major cause of deterioration in the local air quality, with consequent escalating risk of adverse health conditions amongst urban inhabi...

Numerical simulations on airflow within street canyons were performed to investigate the effect of the street aspect ratio and wind speed on velocity profiles inside a street canyon. Three-dimensional Standard, Renormalization Group (RNG) and Realizable k-∊ turbulence model are employed using the commercial CFD code FLUENT to solve the Reynolds-ave...

The paper shares the experience of executing enormous computations by Large Eddy Simulation (LES) for environmental studies, using the commercial Computational Fluid Dynamics (CFD) code FLUENT 6.3® on an Intel Xeon® quad-core workstation and Intel Core® dual-core PC. The computational performancein terms of iteration resource and time expendi...

Previous CFD studies on pollution dispersion problems have largely centred on employing Reynolds-averaged Navier–Stokes (RANS) turbulence closure schemes, which have often been reported to overpredict pollutant concentration levels in comparison to wind tunnel measurement data. In addition, the majority of experimental and numerical investigations...

Air quality in urban and industrial complexes is of great importance owing to the many implications on human and environmental health. Air pollution in built-up areas is typically associated with traffic exhaust emissions. High pedestrian level concentrations are the result of a non trivial combination of pollutant sources, climate and city morphol...

This paper first discusses the aerodynamic effects of trees on local scale flow and pollutant concentration in idealized street canyon configurations by means of laboratory experiments and Computational Fluid Dynamics (CFD). These analyses are then used as a reference modelling study for the extension a the neighbourhood scale by investigating a re...

The work explores the use of Computational Fluid Dynamics (CFD) to the study of air flow and pollutant dispersion in urban street canyons with trees. The study also depicts the evolution from the conventional Reynolds-Averaged Navier Stokes (RANS) solution to the recently more favored Large Eddy Simulation (LES). CFD is becoming an attractive tool...

The performance of three different numerical techniques, i.e. RANS, URANS and LES are compared to determine their suitability in the prediction of urban airflow and pollutant dispersion process. The CFD codes are evaluated against wind tunnel experimental data, and it is observed that LES although more computationally expensive, produces the most a...

An approach to dealing with turbulent flows over a wall mounted cube using the wall y+ (non-dimensional distance from the wall) as guidance in selecting the appropriate grid configuration and corresponding turbulence models is investigated using FLUENT 6.3. The study is divided into two sections – Case I and Case II, dealing with low and high Reyno...

A CFD study is performed for a two-dimensional model to simulate and investigate the turbulent flow interactions between three parallel ridges. Velocity profiles and turbulent kinetic energies are presented to illustrate the effects of varying the ridge height and separation distance. The numerical results are validated against extensive atmospheri...

This paper is devoted to the study of the aerodynamic effects of trees on airflow and pollutant dispersion in urban street canyons. The dispersion of traffic-released pollutants in street canyons lined with trees is analysed by means of both wind tunnel experiments and Computational Fluid Dynamics simulations. Different tree planting and street can...

This paper presents numerical simulations of the aerodynamic effects of trees on the flow field and dispersion of trafficoriginated pollutants in an urban street canyon of W/H = 1 with a perpendicular approach flow. Large Eddy Simulation (LES) is employed for the investigation and is validated against wind tunnel (WT) experiment. Comparisons is mad...

The process of particle sedimentation in a three-dimensional longitudinal basin in a water treatment plant is studied computationally. The fluid mixture mimics typical contaminated water in which the contaminants are represented by a spectrum of 13 different particle sizes. The processes of sedimentation of all classes of particles are simulated. T...

The aerodynamic effects of avenue-like tree planting on air flow and traffic-originated pollutant dispersion in urban built-up areas (i.e. street canyons of width to height ratio, W/H=1) are investigated using computational fluid dynamics techniques and complemented with extensive wind tunnel experiments carried out at the University of Karlsruhe (...

An approach for dealing with turbulent flows over a surface-mounted cube using the wall y+ as guidance in selecting the appropriate grid configuration and corresponding turbulence models are investigated using Fluent. The study is divided into two parts- Part I and Part II, dealing with low and high Reynolds number, respectively. Part I dealt with...