An important phenomenon of delta wing is the mechanism of vortex core, which indicates the increase in lifting force until the occurrence of the vortex breakdown. The computational fluid dynamics (CFD) is very helpful in visualizing and providing analysis of the detailed data. The use of turbulent models will affect the quality of results in obtaining the vortex breakdown phenomenon. This study used several models of turbulence to capture the occurrence of vortex breakdown and compare it with experiments using water tunnel test facility. The results show that all turbulence models give good results at a low angle of attack (AoA), but at a high AoA the DES model gives the results closest to experimental ones with Cl error value of about 1 %. Taking into account the time required and the acceptable level of accuracy, the use of SST and k-ω models is an alternative option for use in the detection of vortex breakdown.

Most of the formulations regarding the characteristics of a shell and tube heat exchanger have a common assumption; namely that the baffle plates are equidistant. This assumption fails to cater the real world scenario for defective baffles as the alteration in a shell and tube heat exchanger invalidates the equidistant baffle spacing of the plates. In this regard, a small six baffles heat exchanger was modeled in the computational fluid dynamics software package and studied by removing each baffle plate one at a time. Effect of removing each baffle plate on the temperature, pressure, heat transfer coefficient, and total heat transfer rate was recorded. It was observed that variation in the pressure drop for the same number of baffle plates varies along the axial order of the plates. The change in pressure drop due to the removal of the baffle plate near the inlet and the outlet was lowest and reaches a maximum in the axial center. It was also found that the plates below the radial center contribute higher towards the overall heat transfer as compared to those above.

In the presented work, the numerical simulations results of the liquid steel flow in the one strand tundish were shown. Influence of the modification and immersion depth in the liquid steel of the ladle shroud and subflux turbulence controller on hydrodynamic structure of the liquid steel movement in the working space of tundish were examined. The ladle shroud shape modification consisted on the decompression and compression of the main supplying stream of the tundish. The mathematical model used in the numerical simulations through physical modeling and industrial trials were validated. The numerical simulation results (using four variants of the modified ladle shroud immersion depth in the liquid steel) in the isothermal conditions using laboratory experiments on the water model were verified. Whereas, the numerical simulation results (using one of the tundish research variant) for non-isothermal were compared with the results from the industrial measurements. Three turbulence models: Realizable k-ε, RNG k-ε and SST k-ω were used in the computer calculations (performed via the Ansys-Fluent computer program). In order to obtain the actual view of the liquid steel flow hydrodynamic structure in the examined tundish for the two mathematical models using different turbulence models, which were most similar to the laboratory experiments and industrial measurements, the numerical simulations were performed in the non-isothermal conditions. The application in the computer calculations of the SST k-ω turbulence model caused the smallest differences between the numerical simulations, laboratory experiments and industrial measurements. Performed tests showed that ladle shroud can be used as a flow control device and the modified ladle shroud immersion at a depth of 0.1 m in the liquid steel caused the shortest range of the transition zone among the tested cases.