The drag coefficient, CD, of an arbitrary shaped object ca;; be calculated by twodimensional hydrodynamic cellular automata. Results spanning nearly four orders of magnitude in the Reynolds number (0.I < Re < 10~) are presented for a simple, hexagonal object, and good quantitative agreement with previous experiments on cylinders is obtained. Hydrodynamical cellular automata (IIDCA), also called...

The measurement and prediction of the aerodynamic performance of airfoils and wings at chord Reynolds numbersbelow105 arebothdifficult and increasingly important in the application to small-scale aircraft.Not only are the aerodynamics strongly affected by the dynamics of the unstable laminar boundary layer, but the flow is decreasingly likely to be two-dimensional as theReynolds number decrease...

Polymer induced drag reduction in turbulent pipe flow was investigated using a non-intrusive laser based diagnostic technique, namely Particle Image Velocimetry (PIV). The drag reduction was measured in a pressure-driven flow facility, in a horizontal pipe of inner diameter 25.3 mm at Reynolds numbers ranging from 35 000 to 210 000. Three highmolecular-weight polymers (polyethylene oxide 2×10 6...

A method for accurately measuring the drag associated with a protuberance on an aircraft has been devised and implemented in a wind tunnel using a C-130 model. The C-130 aircraft has been heavily modified for various different configurations and the impact that these modifications have had on the aerodynamic performance of the aircraft has not been well documented. This paper describes a method...

Aquatic plants convert mean kinetic energy into turbulent kinetic energy at the scale of the plant stems and branches. This energy transfer, linked to wake generation, affects vegetative drag and turbulence intensity. Drawing on this physical link, a model is developed to describe the drag, turbulence and diffusion for flow through emergent vegetation which for the first time captures the relev...

Wave damping by vegetation has been included in many numerical models for coastal engineering primarily through a parameterized expression the wave height decay following Mendez and Losada (2004). CD is an empirical coefficient often derived from reduced-scale laboratory experiments which alpha measured directly. Multiple values of can be determined series tests given as function Reynolds numbe...

This paper presents results of several large-eddy simulations LES of turbulent flow in an open channel through staggered arrays of rigid, emergent cylinders, which can be regarded as idealized vegetation. In this study, two cylinder Reynolds numbers, RD =1,340 and RD=500, and three vegetation densities are considered. The LES of the lowest density and at RD=1,340 corresponds to a recently compl...

The numerical simulation research of the Underwater Unmanned Vehicle (UUV) shell shape is carried out by applying the modern fluid dynamics numerical simulation technology. In the numerical simulation process, while focusing on the characteristics of the UUV shape, this treatise work properly with its computational model, computational domain, computational grid and boundary conditions. Based o...

One of the newest of viscoelastic RANS turbulence models for drag reducing channel flow with polymer additives is studied in different flow and rheological properties. In this model, finitely extensible nonlinear elastic-Peterlin (FENE-P) constitutive model is used to describe the viscoelastic effect of polymer solution and turbulence model is developed in the k-ϵ-(ν^2 ) ̅-f framework. The geome...