Incompressible, turbulent flow past a circular cylinder is computationally investigated by means of Reynolds Averaged Numerical Simulations. Problems in using the wall-functions approach for modeling the near-wall turbulence are demonstrated. As the main turbulence model, the Shear Stress Transport model is employed, by resolving the nearwall layer. A wide range of Reynolds numbers is investiga...

A single bubble is placed in a solid body rotating flow of silicon oil. From the measurement of its equilibrium position, lift and drag forces are determined. Five different silicon oils have been used, providing five different viscosities and Morton numbers. Experiments have been performed over a wide range of bubble Reynolds numbers (0.7 ≤ Re ≤ 380), Rossby numbers (0.58 ≤ Ro ≤ 26) and bubble...

The objective of this study is to minimize the drag coefficient of aerodynamics bodies for a specified design Reynolds number regime. With the aerodynamics model the gradient of the objective function (drag coefficient) cannot be determined analytically. Furthermore, it is expected that the objective function is multi-modal, i.e. it shows more than one minimum. Therefore, the optimization algor...

A direct search method in combination with a DNS/LES numerical approach is applied to optimize the control of the flow around a circular cylinder. The objective is the minimization of the drag coefficient and control is achieved via zero net mass flux actuators. The optimization process has been first evaluated and validated at Reynolds number 500 and then the more demanding flow at Reynolds nu...

The drag coefficient C_{D} of a solid smooth sphere moving in a fluid is known to be only a function of the Reynolds number Re and diminishes rapidly at the drag crisis around Re∼3×10^{5}. A Leidenfrost vapor layer on a hot sphere surface can trigger the onset of the drag crisis at a lower Re. By using a range of high viscosity perfluorocarbon liquids, we show that the drag reduction effect can...

in this research, the effect of surface roughness and bubble injection on skin friction and hydrodynamic drag force has been numerically considered. this research is based on taylor-couette flow. considered flow includes two concentric cylinders which internal cylinder is movable and external is immovable. the effective equations on the flow includes: equations of momentum, continuous, turbulen...

determining characteristics and behavior of fluid flow and obtaining the aerodynamic coefficients are important and considerable tasks in investigation of flow over the bodies. in this research, leading edge radius effects on the flow behavior over a delta wing with a sweep angle of 50 degree at different reynolds numbers between 0.5×106 and 2.5×106 are investigated numerically. three different...

A numerical investigation of unsteady liquid fuel droplet combustion with droplet heating and internal circulation under forced convection is presented. The droplet is burning within an airstream at atmospheric pressure and under zero-gravity conditions. Combustion is modeled using finite rate kinetics and a one-step overall reaction. The numerical model includes a new multicomponent formulatio...

A correlation is obtained for the drag coefficient c ′f of the turbulent boundary layer as a function of the effective boundary layer Reynolds number Re that we previously introduced. A comparison is performed also with another correlation for the drag coefficient as a function of the traditional Reynolds number Reθ , based on the momentum thickness of the boundary layer proposed recently by R....

CD = dimensionless mean drag coefficient, 2F D= fU meanD F D = drag force per unit spanwise length on the cylinder and plate, Nm 1 D = diameter of the cylinder, m E = dimensionless Young’s modulus, E = fU mean f = dimensionless oscillation frequency of the plate, f D=Umean Re = Reynolds number, fUmeanD= Umean = mean velocity at the left boundary of the channel, ms 1 V = dimensionless dilatation...