Natural convection heat transfer in a square cavity induced by heated plate is investigated using the lattice Boltzmann method. A suitable forcing term is represented in the Boltzmann equation. With the representation, the Navier-Stokes equation can be derived from the lattice Boltzmann equation through the Chapman-Enskog expansion. Top and bottom of the cavity are adiabatic, the two vertical walls of the cavity have constant temperatures lower than the plate’s temperature. The flow is assumed to be two-dimensional. Air is chosen as a working fluid (Pr=0.71). The study is performed for different values of Grashof number ranging from 103 to 105 for different aspect ratios and position of heated plate. The effect of the position and aspect ratio of heated plate on heat transfer are discussed. With increase of the Grashof number, heat transfer rate is increased in both vertical and horizontal position of the plate. The obtained results of the lattice Boltzmann method are validated with those presented in the literature.

The mesh generation process as a time-consuming and computational effort in the numerical methods always has been paid attention to by researchers to provide more accurate and fast methods. In this study, an accurate, fast, and userfriendly method of mesh generation has been developed by combining the image processing method with Computational Fluid Dynamics (CFD). For this purpose, a turbulent flow around a single square as a bluff body is simulated by homemade code using MATLAB software as a test case to illustrate the mentioned method. The conservative Equations have been discretized using the finite volume method based on the Power-la scheme. Utilizing useful filters on the imported gray-scale digital image provides edge detection of the obstacle in the computational domain. After the edge detection step, an orthogonal, structured, and staggered mesh is generated.

This study aims to explore the natural convection, magnetohydrodynamics and ternary nanofluids containing Fe3O4, Cu and TiO2 in water-ethylene glycol within a hexagonal cavity containing a square obstacle. The Finite element method is utilized through the COMSOL Multiphysics 6. 1 software. By utilizing visual representations, the influence of key variables on flow patterns, temperature distribution, and local Nusselt number is effectively illustrated. Simulations were carried out with Rayleigh number ranging from 103 to 105, heat source and absorption coefficients ranging from-5 to 15, and Hartmann numbers of 0, 70 and 90. The Prandtl number for ethylene glycol is 29. 86. The findings of this research confirm that the proper incorporation of nanoparticles significantly enhances the heat transfer properties of base fluids.

In this paper, natural convection heat transfer in a closed square cavity with a hot triangular obstacle at temperature TH simulated by Finite Element Method. The top and the bottom walls are insulated while the left and the right walls are maintained at a constant temperature Tc (TH> Tc). The used method is validated against the existing numerical results and an excellent agreement between the results was found. The flow is assumed to be two-dimensional and air is chosen as a working fluid. The effect of different parameters such as Rayleigh number (Ra =103, 104, 105, 106), different position of obstacle inside cavity (H=L=0. 1, 0. 4, 0. 7) and different angle of obstacle (θ '=00, 900, 1800, 2700) at different aspect ratio (AR =0. 2, 0. 4, 0. 6, 0. 8) on fluid flow and heat transfer inside the channel are investigated. The results showed that by increasing the Rayleigh number and increment of aspect ratio, the rate of heat transfer is increased. Also, enhancement the distance of obstacle from left and bottom walls of cavity, lead to decrement rate of heat transfer and the maximum values of mean Nusselt number are shown respectively at angles of 0, 90, 270, 180 degrees.

In this paper, the heat transfer to the fluid, passing through the double forward facing step (FFS) channel with square obstacle is enhanced by Taguchi’ s S/N ratio analysis. Flow through the forward facing step channel has a wide range of applications in thermal systems due to its flow separation and subsequent reattachment, which in turn enhances the heat transfer. Flow separation and reattachment mainly depends on the channel geometry, obstacle and flow parameters. Hence, in this study, step height in the channel, obstacle size, Reynold’ s number and gap between the obstacle and step are included as control paramters in the S/N ratio analysis for maximizing the heat transfer. These parameters are varied through three levels of values and L9 orthogonal array is employed. Numerical simulation technique is applied to analyze the L9 cases through computational fluid dynamics code. From the simulation, the rise in temperature at the channel exit with reference to the inlet is predicted. The best values for the identified control parameters conclude to a temperature raise of about 2. 86 C. The optimum result obtained from the S/N ratio analysis is also compared with response surface methodology technique. Finally, analysis of variance (ANOVA) is conducted and identified that step height and flow Reynold’ s number affect the heat transfer by about 79 and 19%, respectively.

Detecting and preventing incidents with obstacles is a challenging problem. Most of the common obstacle detection techniques are currently sensor-based. Mobile robots like Small Unmanned Aerial Vehicles (UAVs) are not able to carry obstacle detection sensors such as radar; therefore, vision-based methods are considered, which can be divided into stereo and mono techniques. Mono methods are classified into two groups: Foreground-background separation, and brain-inspired methods. Brain-inspired methods are highly efficient in obstacle detection. A recent research in this field has focused on matching the Scale- Invariant Feature Transform (SIFT) points along with SIFT size-ratio factor and area-ratio of convex hulls in two consecutive frames to detect obstacles. However, this method is not able to distinguish between near and far obstacles nor the obstacles in a complex environment and, thus, is sensitive to wrong matched points. This paper aims to solve the aforementioned problems through using the distance-ratio of matched points. Then, every point is investigated for distinguishing between far and near obstacles. The results demonstrated the high efficiency of the proposed method in complex environments. The least achieved accuracy of the algorithm was 60.0%, and the overall accuracy was 79.0%.

In this everchanging world, any policy - makersand expertshave been focused on the problems of employment and it"s complexities. It is obvious that the frame of country"s youth population and increasing work inquiries, requires more attention to this phenomenon. The fact is that, in due to change in traditional economies, in providing imployment and generating production, some temporary industrial projects, are not efficient. In other words, in today"s country situations, which have been most affected by external elements, to decfease the problem of unemployment, the new job opportunities should be defined and introduced to the society. In this paper, the focus woutd be on analysing the infrastructure obstacles facing the problems of country"s unemployment. Finally, with more attention to the different economic sectors with high potential, educational system and production development, the ways that can get rid of this crisis, will be presented.

Bushehr is one of the famous and historical ports. it has an important place in economy politics history and sailing of Iran and Persian gulf. in duration of Afsharieh Zandieh Qajar and even initial Pahlavi Bushehr port was not the largest port in Sothern iran but also considered as the most important and famous ports of Persian gulf. Near about 20 consulates from different countriesare located in the region. In 19 th century economy of Bushehr was basedon Business and commercial sailing. In crease in Bushehr commercial sailing in 19 th century resulted in forming a powerful commercial societythere in a way that great businessmen and capital owners migrated from different parts of iran and resded in bushehr. Despite of this prominent historical place in second half of 20th century bushehr dropped behind and left its place to rivals. As the moment it is considerd as the second class ports in Persian gulf. this research aims at exploring historical obstacles in development of bushehrand consequently the key question would be as: what are the historical obstaclers in deveploment of busheh? The main hypothesis in this study is weakness and degeneration of bushehr commercial society along with some other factores which ended in bushehr decline part. Obviously other factores will be also be studied in this research. Results show that bushrhr development dependes on resolving historical obstacles.

Hydraulic structures in some cases, cause to produce obstacles in path of the flow that create oscillating vortices in downstream of the obstacles. Vortices produce oscillating forces to the obstacle that are harmful for the stability of structure. In recent years this phenomenon is used to create clean energy. In this study, oscillation of an obstacle in the presence of a fixed obstacle at the upstream was examined. The experiments on triangular block were carried out under varying discharge and different upstream distances. The main objective of this study was to investigate the effect of parameters of velocity and upstream obstacle distance on the oscillation frequency. Using dimensional analysis, the dimensionless parameters of Strouhal number, Reynolds number and ratio of distance to diameter were obtained. The charts of the relationship of the Reynolds number and also the ratio of distance to diameter vs. the Strouhal numbers were plotted. Finally, a new relationship was presented using data analysis and spss20 software to estimate the Strouhal number. Verifying the proposed relation, confirmed a fairly good prediction of this relation.