A specific feature of three-dimensional bluff body wakes, flow bistability, is a subject of particular recent interest. This feature consists of a random flipping of the wake between two asymmetric configurations and is believed to contribute to the pressure drag of many bluff bodies. In this study we apply the modelling approach recently suggested for axisymmetric bodies by Rigas et al. (J. Fl...

Direct numerical simulations ~DNS! of a turbulent channel flow at low Reynolds number (Ret 5100,200,400, where Ret is the Reynolds number based on the wall-shear velocity and channel half-width! are carried out to examine the effectiveness of using the Lorentz force to reduce skin friction. The Lorentz force is created by embedding electrodes and permanent magnets in the flat surface over which...

The assessment of turbulence model performance in predicting ow elds that are directly relevant to industrial needs has become increasingly important. In aerodynamics, many problems exist for which the performance of some turbulence models is ambiguous at best and incorrect at worst. The application of many di erent turbulence models to a particular problem is a lengthy process that can lead to...

The wakes of wall-mounted small (square) and large (long) depth-ratio rectangular prisms are numerically studied at Reynolds numbers 50–250. significantly alters the dominance lateral secondary flow (upwash downwash) in wake due to reattachment leading-edge separated on surfaces prism. This changes topology by varying entrained region changing distribution vorticity. Thus, magnitude vorticity d...

Two distinct scaling procedures were found to predict the diameter effect for different types of drag-reducing fluids. The first one, which correlates the relative drag reduction (DR) with flow bulk velocity (V), appears applicable to fluids that comply with the 3-layers velocity profile model. This model has been applied to many polymer solutions; but the drag reduction versus V scaling proced...

The air-sea drag coefficient controls the transfer of momentum from wind to water. In modeling storm surge, this coefficient is a crucial parameter for estimating the surge height. This study uses two strong wind events on Lake Erie to calibrate the drag coefficient using the Coupled Ocean Atmosphere Wave Sediment Transport (COAWST) modeling system and the the Regional Ocean Modeling System (RO...

An analogue technique for the approximate solution of the biharmonic equation is used to determine the viscous drag at Reynolds number approaching zero for cylinders falling symmetrically in a liquid between parallel walls. Results obtained show good agreement with numerical solutions, with results by direct experiment and with the work of other authors. Streamlines are obtained with a maximum ...

We study experimentally the slowing of viscous vortex rings. In particular we do so using the concept of drag coefficient, which is a bulk coefficient which aims to capture the various mechanisms of slowing that can occur. At early times of flight the ring slows at a certain rate. After some time, instabilities (which we refer to as Kelvin waves) begin to form on the ring and there is a transie...

A blended drag coefficient model is constructed using a series of empirical relations based on Reynolds number, Mach and Knudsen number. When validated against experiments, the produces matching values with standard deviation error 2.84% maximum 11.87%. The used in Lagrangian code which coupled to hypersonic aerothermodynamic CFD code, particle velocity trajectory are experimental results. comp...