Numerical simulation of turbulent heat transfer and fluid flow in different tube designs

Numerical simulation was carried out to study the heat transfer, friction factor and thermal performance of water inside different tubes induced with different twisted tapes. The purpose is to ascertain which of the tube designs gives the best performance when compared with the plain tube. The tubes were under uniform wall heat flux condition and Reynolds number in the range 5000 ≤ Re ≤ 20000 were considered. RNG κ − ε equation model was selected for the numerical simulations and RANS equations were employed to render the Navier-Stokes equations tractable. The best performance was obtained when the tube was fitted with alternate-axis triangular cut twisted tape. Its Nusselt number and friction factor are respectively 2.07 – 3.33 and 10.65 – 13.1 times better than that of a plain tube and its thermal performance factor is 1.35 – 1.43 times better than that of the tube with plain twisted tape

CFD Study of Behavior of Transition Flow in Distinct Tubes of Miscellaneous Tape Insertions

Application of transition flow can be found in several processes and systems. It has been revealed through findings from various researchers that the values of Reynolds numbers at which transition flow occurs vary. In the current work, investigations were numerically conducted by Fluent on transition of water flow in three assorted plain tubes fitted with miscellaneous tape insertions. They are plain tube with crossed-axes-circle-cut tape insert (C-C tube), plain tube with crossed-axes-triangle-cut tape insert (C-T tube), and plain tube with crossed-axes-ellipse-cut tape insert (C-E tube). The focus of the work is to explore the influence of the tape insertion on commencement and finish of transition flow in the tubes with respect to the Reynolds number of the flow. The Reynolds number (Re) taken into account for the transition flow is 2,150≤Re≤4,650, and the variation of Shear-Stress Transport κ-ω model that deals with transition flow was utilized. The results showed that transition flow starts at Re=2,300 and finishes at Re=4,400 in C-T tube, starts at Re=2,780 and finishes at Re=4,610 in C-C tube, but starts at Re=2,550 and finishes at Re=4,500 in C-E tube. The Nusselt number in C-T tube is 19.3% to 45.6% higher than that in C-C tube, but the Nusselt number in C-T tube is 3.6% to 28.3% more than that in C-E tube. The friction factor in C-T tube is 2.15% to 4.56% higher than that in C-C tube; the friction factor in C-T tube is 0.83% to 3.33% more than that in C-E tube. These results indicate that for the case of the tubes considered in this work, the C-T tube, which is the first one in which transition flow commences and ends, has the highest Nusselt number, but C-C tube, in which transition flow commences and finishes last, has the least Nusselt number. Interestingly, the same phenomenon applies to the friction factor. Doi: 10.28991/HIJ-2022-03-02-02 Full Text: PD

Numerical simulation of turbulent heat transfer and fluid flow in different tube designs

Numerical simulation was carried out to study the heat transfer, friction factor and thermal performance of water inside different tubes induced with different twisted tapes. The purpose is to ascertain which of the tube designs gives the best performance when compared with the plain tube. The tubes were under uniform wall heat flux condition and Reynolds number in the range 5000 ≤ Re ≤ 20000 were considered. RNG κ − ε equation model was selected for the numerical simulations and RANS equations were employed to render the Navier-Stokes equations tractable. The best performance was obtained when the tube was fitted with alternate-axis triangular cut twisted tape. Its Nusselt number and friction factor are respectively 2.07 – 3.33 and 10.65 – 13.1 times better than that of a plain tube and its thermal performance factor is 1.35 – 1.43 times better than that of the tube with plain twisted tape

AN EMPRICAL INVESTIGATION OF HUMAN RESOURCES DEVELOPMENT IN NIGERIAN PUBLIC SECTOR

The development of people at work beyond level at which they assumed duty when appointed has been a source of concern to all stakeholders including Psychologist. The public sector is made up of civil service and parastatals with which the government executes its programmes. Getting the best out of any employee in the public sector in Nigeria in Nigeria requires adequate training However, the possibility of this training has been an herculean task due to lack of adequate training policy and provi- sion of fund for the required training. This research investigates the human resources development situation in the public sector of Nigeria by conducting a survey of one thousand and two hundred hu- man resource officers to ascertain their perception of human resource development. Data were col- lected with a structured questionnaire and analyzed with descriptive statistics while hypothesis formu- lated was tested with t-test. The study revealed that human resources development is not just for indi- vidual, but also for the organization as it improves performance

Household Level Factors Responsible for Gender Poverty Among Cassava Farmers in Odeda Local Government Area of Ogun State

Poverty is multidimensional, enduring and is prevailing not only globally, but also particular cultural, political and economic features of a specific country increasing it. The gulf between haves and have-nots has lingered. Gender disparities, inequality, spatial dimensions, political instability, week institutions and lack of spiritual capital causes the poverty. The objective of this study was to examine the determinants of poverty among cassava producing households by gender of household heads in Odeda local government area of Ogun state. A total of 120 cassava farming household comprising of 76 male headed households and 46 female headed households were interviewed using structured questionnaire, in obtaining information from them. The study revealed that there is a positive relationship between the household size and poverty status for both the female headed households and male headed households and also the age of the household head has a negative relationship with the poverty status of the female household while farm experience and off farm activities were negatively related to the poverty status among the male household. Also, it was found out that neither of the households dominates one another in the poverty analysis. It was concluded that the household size of both the male and female households is an important determinant of poverty status as it was significant to the poverty status of the respondents.&nbsp

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Numerical investigation of heat transfer and fluid flow of water through a circular tube induced with divers' tape inserts

An investigation was carried out to analyse numerically heat transfer and flow characteristics of water through a circular tube induced with different twisted tapes. The aim is to know which of the tube designs gives the best performance when compared with a plain tube. Turbulent flow was considered, the walls of the tubes were under uniform wall heat flux, Reynolds number was between 5000 and 20,000, and RNG κ-ε model was selected for the simulations. The shape of cuts on the tapes has effects on the performance of the induced tubes. The tube fitted with alternate-axis triangular cut twisted tape has the best performance as its Nusselt number and friction factor are 1.63–2.18 and 2.60–3.15 times, respectively, that of the tube fitted with plain twisted tape while its thermal performance factor is 1.35–1.43 times that of the tube with plain twisted tape. New correlations were developed for the Nusselt number and friction factors, and reveal that the Nusselt number obtained from the new correlation agrees well with the correlation proposed by Thianpong et al. with a discrepancy of 2.21%. For the friction factor, the discrepancy is 3.01%

Influences of variation in geometry of tape insert on thermal performance and flow characteristics in tubes

This paper presents the results of the numerical investigation carried out on different tube designs to assess the impacts of variations in the geometry of the twisted tape on heat transfer, friction factor and thermal performance of water inside the tubes. Alternate-axis triangular cut twisted tape was considered and its pitch and width, as well as the perimeter of the cuts on it were varied. The walls of the tubes were subjected to a uniform heat flux condition. The results of the investigation revealed that the thermal performance of the tube designs improved with an increase in the width of the tape and an increase in the size of the cuts on the tape but diminished as the pitch of the tape increases

CONSTRUCTING AN INTELLECTUAL PROSPECT OF VENTURE MANAGEMENT PRACTICES: A DIVIDE BETWEEN INFORMAL AND FORMAL ELECTRONICS ENTREPRENEURSHIP

The practice of venture management has recorded success in the United States of America and India. This brought about the turn-around of businesses, both prospect and existing formal business operators in these nations. In the case of Nigeria, banks and other financial institutions have ended up providing advice to successful firms to acquire business organisation in distress and at times are the leaders in that particular industry, thus bringing about unemployment. It is of a note that entrepreneurs are the drivers of a nation’s economy irrespective of government practices. It is based on this premises that the relevance of transition from informal to formal entrepreneurship practices must occur for the existence of economic growth. To bridge this gap in literature, a comparative study on venture management practices and expected performance for practicing entrepreneurs in the informal and formal sector is require