Papers by chinedum Okafor
IJSRP, 2021
The study simulated the airflow pattern, thermal comfort and occupational exposure to CO 2 under ... more The study simulated the airflow pattern, thermal comfort and occupational exposure to CO 2 under two ventilation modes using computational fluid dynamics (CFD). A wall supply diffuser was located at the floor level for the displacement ventilation case while the supply air diffuser was placed at the ceiling level for the mixing ventilation mode. The manikin served as a jet, exhaled air through the nostrils downward at an angle of 45 degrees below the horizontal line. The CO 2 species was modeled as a passive scalar transport convection-diffusion equation. From the result obtained, the mixing ventilation case showed a low level of CO 2 concentration than in the displacement ventilation case. Also, higher vertical temperature gradient was noticed in the displacement ventilation case as opposed to the mixing ventilation scenario. Lastly, the mixing ventilation case showed higher tendencies of local draft than displacement ventilation case.
IJERAT, 2021
This paper studied wind-driven natural ventilation in a room using computational fluid dynamics m... more This paper studied wind-driven natural ventilation in a room using computational fluid dynamics model in order to determine the airflow pattern, draft and pollutant dispersion within the CFD model. The different natural ventilation strategies were studied in cases namely: CASE 1(Single sided ventilation), CASE 2(Cross Ventilation), CASE 3(Bernoulli and Cross Ventilation) and CASE 4(Double single sided ventilation). The CFD simulation was performed with the 3D steady state RANS approach using RNG-KE turbulent model to provide closure. From the result obtained, the author found out that Firstly, CASE 1 and CASE 4 showed a reduce level of air draft (V< 0.2m/s) within the room unlike the CASE 2 and CASE 3 where the air speed on the room occupants most especially at the ankle and head region were much higher than that recommended as per BS EN 7730. Secondly, CASE 2 showed greater efficiency in dealing with pollutant dispersion then followed by CASE 3 and CASE 4 respectively. The concentrations in almost every part of the room for CASE 2 were well within the acceptable range recommended for human occupancy as per BS EN 7730.
European Journal of Engineering Research and Science
The study presents a numerical model for evaluation of the stresses in corrugated sheets under be... more The study presents a numerical model for evaluation of the stresses in corrugated sheets under bending. The numerical analysis was performed from a three dimensional finite element model. From the analysis, the most intense tensional stress occurs in the trough and bottom surface of the corrugated sheet. While the most intense value of compressive stress occur in the crest and top surface of the sheet. Based on the principal stress contour diagram, the researcher also observed that the maximum uniformly distributed load carrying capacity of the fiber-cement corrugated sheet under bending, considering the linear material properties is 710N.
European Journal of Engineering Research and Science
Delay in payment to contactors and other relevant parties have caused serious problem on the succ... more Delay in payment to contactors and other relevant parties have caused serious problem on the successful execution of construction projects in the country. It causes several problems to the contractor and other participants. The aim of this study is to determine the causes of delayed payments in the construction industry. The objective of this study is to identify the causes of delayed payment. In order to obtain valid data for the study, questionnaires were designed and distributed to a randomly selected sample of one hundred individuals among contractors, subcontractors, consultant and clients in the Nigerian construction industry. In total, eighty five completed questionnaires were returned and then analysed statistically. The total mean score was used to determine the ranking of the results of the study. Client’s disagreeing on the valuation of work done, slow processing of variation orders and poor quality of works were the major causes of delayed payment identified in the study...
European Journal of Engineering Research and Science
High-rise buildings may experience high levels of vibrations under the actions of wind which caus... more High-rise buildings may experience high levels of vibrations under the actions of wind which cause building motions, adversely affecting serviceability and occupant comfort. The paper analyzed the vortex shedding responses of a multistory building with moment resisting frame. It presents a numerical model based on computational wind engineering technique to simulate the wind action over a typical high-rise building using wind speed data of Lagos state Nigeria. The vortex shedding frequency of the vortices and the natural frequency of vibration of the entire high-rise building structural system were calculated by computing fast Fourier transform algorithm (FFT) of the force coefficient and finite element analysis (FEA) of the structural system respectively. From the result obtained, the vortex shedding frequency of the wind vortices was lower than the fundamental frequency of vibration of the typical high-rise building. Hence, vortex shedding was not responsible for the failure of hi...
European Journal of Engineering Research and Science
This study carried out a comparative study to evaluate the air-conditioning performance of an off... more This study carried out a comparative study to evaluate the air-conditioning performance of an office space under two typical ventilation modes (displacement and mixing ventilation system). A wall supply diffuser is located at the ceiling height for the mixing ventilation case, whereas, the supply diffuser is at the floor level for the displacement ventilation case. In both cases, the exhaust grill is located at the ceiling. From the result of the simulation, the researchers observed that the displacement ventilation system could have a higher risk of discomfort relating to vertical temperature gradient than when compared to the mixing ventilation case. More so, the simulation result indicates that the temperature distribution in an office building is a function of the type of ventilation system adopted and marginally affected by the diffuser arrangement.
European Journal of Engineering Research and Science
This study focuses on analyzing the response of a typical ribbed aluminum panel under flexure. A ... more This study focuses on analyzing the response of a typical ribbed aluminum panel under flexure. A three dimensional finite element model was developed to stimulate the static flexure behavior. The model is a 2.0m (length) x 1.0m (width) x 0.005m (Thickness) with a rib height of 0.038m, crest width of 0.019m and pan distance at 0.055m between intermediate ribs. The load deflection response of the aluminum panel under different flexural loading condition was stimulated. The linear material properties, displacement, stress and strain captured were discussed under static conditions. From the result obtained, the maximum uniformly distributed load carrying capacity of the ribbed aluminum roofing panel under flexure, considering the linear material properties is 665N.
IJERAT, 2021
The paper analyzed the wind-induced pollutant dispersion in a built environment using computation... more The paper analyzed the wind-induced pollutant dispersion in a built environment using computational fluid dynamics simulation. SF6 was used as the tracer gas released from a roof stack. The steady-state analysis used to develop the adaptive mesh was carried out using the RNG-KE turbulence model. The computational domain and boundary condition for the wind flow on the urban area was adopted as recommended by the Cost guideline. Also, the SF6 species was modeled as a passive scalar transport convection-diffusion equation. From the result, it was observed that the funnel effect and vortex shedding effect reduces the concentration level of pollutants within a locality.
European journal of engineering research and science , 2017
—This paper analyzed the effect of wind loadings on high-rise building for different terrain cate... more —This paper analyzed the effect of wind loadings on high-rise building for different terrain categories. The wind speed and design wind pressure for the different terrain categories adopted for this study were calculated as per logarithmic wind profile equation and BS6399-2:1997 respectively. Also, the nodal displacement of a 3D high-rise building model with reference to the calculated design wind loads were performed using finite element analysis software(STADDPROV8I). From the result obtained, it was shown that Terrain category IV when compared to other terrain categories recorded lower wind speed and pressure from the ground to a height of about 10m. The writer also observed that at greater terrain category(TC4), the wind speed and pressure tends to be much higher at the top floors(10m-48m) of the high-rise building whereas, terrain categories (TC3, TC2, TC1) recorded lower wind speed and pressure at that same height(10m-48m). this disparity however was discovered to be due to a phenomenon known as gust effect. Also, the nodal displacement for the different terrain category (TC4, TC3, TC2 and TC1) on each floor of the high-rise building increased uniformly in respective pattern as the height of the 3D model increases. In conclusion, the author therefore remarks " the greater the terrain category, the lowest is the wind speed in the roughness sub layer and the longer height it takes to reach gradient wind speed " .
Over the years, wind loading codes has been a crucial tool in determining design wind loads on bu... more Over the years, wind loading codes has been a crucial tool in determining design wind loads on buildings. Due to the limitations of these codes especially in height, wind tunnel testing is recommended as the best approach in predicting wind flow around buildings but carrying out wind tunnel testing in the preliminary as well as final design stage of a project has proven uneconomical and incurs additional cost to the client. In response to this, CFD which is a virtual form of wind tunnel testing was developed. From immersive researches and experiments carried out by previous researchers, best practice guidelines have been given on the use of CFD in predicting wind flow around buildings. This paper compares the results of a case study application of computational fluid dynamics simulation in determining the wind loads on the facade of a typical 48.8m high-rise building to the predictions given in British wind Standards BS6399-2:1997, using wind speed data of Lagos state Nigeria. From the results, it was shown that the latter can offer considerable saving and highlight problem areas overlooked by the British code of practice (BS6399-2:1997).
Advance in Science technology and engineering system journal , 2017
This paper analyzed wind loading responses of Aluminum Wall cladding panels in Tall Building usi... more This paper analyzed wind loading responses of Aluminum Wall cladding panels in Tall Building using Ikeja Lagos State Nigeria. The wind loads were calculated according to Standard and Specification From BS6399-2:1997 Using the wind speed data of Lagos state Nigeria and finite element analysis, we predicted the responses of these Aluminum wall Cladding panels to the design wind loads being calculated. The result of the calculation from BS6399-2:1997 showed that the aluminum cladding panels located on the facade upwind was subject to positive pressure, which increases with height. Also, the cladding panels located on the leeward, as well as sidewalls, were subjected to negative pressure, which tended to be high at the top and bottom corners due to flow separation. From the result of the modeling and analysis, the researcher found out that stresses on the aluminum wall cladding panels were generally below the material yield point, showing that the high wind speed was not the reason for the collapse of aluminum cladding panels in the locality being considered. Instead, the reality lies on one or more issue on the materials construction and placement as discussed.
European journal of engineering research and science , 2018
Abstract—The significant development in computer resources in the past years has increased the ... more Abstract—The significant development in computer resources in the past years has increased the awareness of computational fluid dynamics as an alternative tool to the costly wind tunnel testing. The paper presented the application of CFD technique for a case study in simulating an existing site together with a proposed building and the local landscape. Finally, the limitations of the code analytical methods to the CFD method for wind around building analysis were discussed. From the result obtained, it was observed that the British standard (BS6399-2:1997) procedures are based on general assumptions and are not always conservative and do not provide accurate wind load results due to complex geometrical shapes, aerodynamic interaction, torsion, and load combinations as discussed in section VII.
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Papers by chinedum Okafor