Fluid flow around bluff bodies such as circular and rectangular (square) cross‐sections is a fundamental fluid mechanics problem and has been a popular focus of research for many years. Several engineering applications—including offshore structures, bridge piers, and pipelines—can be modeled as cylinders. This study numerically investigated the flow field around cylinders of the same characteristic length under identical flow conditions ranging from laminar (Reynolds number [Re] = 2) to turbulent (Re = 4 × 10⁶). Two‐dimensional simulation analyses were performed using the shear stress transport k‐omega turbulence closure model and commercial software. Simulation results showed good agreement with the literature. Cylinder shape was found to significantly affect the flow field. Under the same initial flow conditions, wake downstream of the square cylinder was found to be much more turbulent than that of the circular one. In addition, as Re increased, the turbulence of the wake flow increased and its length downstream of the cylinders increased.

Hydrokinetic turbines have gained importance due to rapid developments in the field of renewable energy. There are several applications for large-scale hydrokinetic turbines in marine environments; however, the number of small-scale designs for rivers and channels is limited. In the present study, a fixed-speed, stall-regulated riverine hydrokinetic turbine rotor has been designed through an optimization process and simulated using computational fluid dynamics (CFD) analysis methods. The blades and rotor were optimized by genetic algorithm methods. Simulations were conducted using commercially available software with a shear-stress transport (SST) $k\text{-}\omega$ turbulence closure model. In the simulations, the performance in terms of power, torque, and thrust were found to be in good agreement with the optimization parameters. The optimized hydrokinetic turbine is named TIGRIS-27 H, and is a three-bladed horizontal-axis energy converter rotating at 45 revolutions per minute (rpm) and generating up to 27 kW power at the rated velocity of $2.7{\mathrm{ms}}^{-1}$ with an average power coefficient of 0.43.

An explicit neural network formulation (ENNF) is developed for estimating reference evapotranspiration (ET0) using daily meteorological variables obtained from the California Irrigation Management Information System (CIMIS) database. First, the ENNF is trained and tested using the CIMIS database, and then compared with five conventional ET0 models, as well as the multiple linear regression method. Statistics such as average, standard deviation, minimum and maximum values, and criteria such as mean square error and determination coefficient are used to measure the performance of the ENNF. Daily atmospheric data of four climatic stations in central California are taken into consideration in the model development and those of three other stations are used for comparison purposes. The meteorological variables employed in the formulation are solar radiation, air temperature, relative humidity and wind speed. It is concluded from the results that ENNF offers an alternative ET0 formulation, but that the... Résumé Une formulation de réseau de neurones explicite (FRNE) est développée pour estimer l'évapo-transpiration de référence (ET0) à l'aide de variables météorologiques journalières obtenues de la base de données du système d'information de la gestion de l'irrigation en Californie (CIMIS). La FRNE est entraînée et testée à l'aide de la base de données CIMIS, puis elle est comparée à cinq modèles conventionnels d'ET0, ainsi qu'avec la régression linéaire multiple. Des statistiques comme la moyenne, l'écart type, les valeurs maximale et minimale, et des critères comme l'erreur quadratique moyenne et le coefficient de détermination sont utilisés pour mesurer les performances de la FRNE. Les données atmosphériques journalières de quatre stations météorologiques du centre de la Californie sont prises en compte dans le développement du modèle et celles de trois autres stations sont utilisées pour des comparaisons. Les variables météorologiques utilisées dans la formulation sont le rayonnement solaire, la tempér...