Search

The present study numerically describes the nature of the arising boundary layer along an isothermal vertical plate, on which is mounted a bluff body. The investigation parameter is the cross-section shape of the bluff body, which includes a square, circular, and prismatic cylinders. To entirely embedded cylinder in the incoming boundary layer, the simulations include short cylinders with an aspect ratio fixed to unity. The cylinder location related to the leading edge of the plate is identified by considering laminar Grashof number, which experimentally is investigated in parallel work. Besides this, the experimental study of a square cylinder, confirms the reliability and accuracy of numerical simulation. As a result, by providing steady-state simulation, the presence of a complex vortex structure is proved. Besides, the effects of the cross-section shape of the cylinder on the dynamics characteristics of the vortex system include vorticity strength, size, and position are categorized. Finally, the significant effects of formed juncture flow on the three-dimensional thermal characteristics of arising free convective boundary layers along with the heated vertical plate are emphasized by a description of heat transfer coefficients. In particular, the importance of the frontal bluntness of cylinder in the field of thermal management is claimed, where the maximum value of the heat transfer coefficient for circular, prismatic, and square cylinders, respectively appears at the angular coordinates of0, 45, and 90 degrees, which correspond with the location of cylinder edges.

The system consisting of two rigid bodies in a viscous fluid is considered. The main body with mass M is placed in a viscous incompressible fluid, and the body with mass m moves inside the main body. This system is known as vibrobot which can be used in arbitrary inspection fluid mechanic objects such as oil industries pipes and tanks, as well as marine industries, medicine, etc. In this paper, the interaction between the vibrobot and viscous fluid is studied to achieve the motion laws of the vibrobot with the harmonic oscillation of internal mass. Also the flow structure around vibrobot and its effects on the hydrodynamic force acting on the vibrobot are investigated. Analyses are carried out by direct numerical simulation of the vibrobot motion in a viscous fluid by OpenFOAM package. Calculations are performed for the following combinations of control parameters; The ratio of the viscous fluid mass to the vibrobot mass μ_1=0.35, the ratio of the internal mass to the vibrobot mass μ_2=0.325 and dimensionless oscillation frequency f=1/5, when Reynolds number takes values in the range of 50