In this paper, the passive control of flow past a semi-circular cylinder is investigated. This control is achieved by adding a porous medium between the solid obstacle and the incompressible fluid in order to reduce drag forces and regularize the flow. A vortex-penalization method is chosen to easily model the flow in the different media. Several configurations of the porous layer are investiga...

We study the stochastic motion of a Brownian particle driven by a constant force over a static periodic potential. We show that both the effective diffusion and the effective drag coefficient are mathematically well-defined and we derive analytic expressions for these two quantities. We then investigate the asymptotic behaviors of the effective diffusion and the effective drag coefficient, resp...

The aim of this study was to compare the swimming hydrodynamics assessed with experimental and analytical procedures, as well as, to learn about the relative contributions of the friction drag and pressure drag to total passive drag. Sixty young talented swimmers (30 boys and 30 girls with 13.59±0.77 and 12.61±0.07 years-old, respectively) were assessed. Passive drag was assessed with inverse d...

with speed increasing in high-speed trains, due to limitations of other types of brakes, aerodynamic brake has become an important braking method. in this task to make better use of brake’s panel different configurations are examined and the best panel shape which provides the reasonable drag coefficient is introduced. the results of simulations are carried out with the computational fluid dyna...

One of the most efficient methods of reducing drag on planing craft is the use of transverse step on the bottom of a hull. Applying steps on the hull reduces the contact area with water and as a result, it reduces drag of the craft. Planing craft are able to have one or two transverse steps. In this paper, numerical hydrodynamic performance of the stepped planing craft and its step height effec...

Abstract The paper presents an investigation of the slip length effect on flow around a circular cylinder at Reynolds number Re = 2.5·10 5 . study was performed by means numerical simulation with URANS approach based k -ω SST model. Calculations show significant patterns. With increase in length, drag coefficient noticeably decreases and pulsations lift force reduce. separation from is delayed,...

Abstract The paper presents the derivation of a new equivalent skin friction coefficient for estimating parasitic drag short-to-medium range fixed-wing unmanned aircraft. is derived from an aerodynamic analysis ten different aircraft used surveillance, reconnaissance, and search rescue missions. simulated using validated unsteady Reynolds-averaged Navier Stokes approach. UAV’s significantly inf...

To reduce the drag of a cylinder, numerical simulations and experiments for both smooth cylinder circular with dimpled surface are carried out in this paper. The simulation focuses on variation pressure coefficient, skin friction vortex shedding strength surface. It is found that structure can effectively within specific range Reynolds number, maximum reduction rate reaches up to 19%. Another c...

Adaptive morphing trailing edge wings have the potential to reduce the fuel burn of transport aircraft. In this paper, we quantify the aerodynamic performance benefits of a morphing trailing using aerodynamic design optimization. The aerodynamic model solves the Reynolds-averaged Navier– Stokes equations with a Spalart–Allmaras turbulence model. A gradient-based optimization algorithm is used i...