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Principles and Applications of Plasma Actuators
Published in Ranjan Vepa, Electric Aircraft Dynamics, 2020
Another method of controlling drag is to introduce continuous suction from within the boundary layer region. Continuous suction, using carefully designed and positioned slots lying in a region below the laminar boundary layer, could be used to keep the boundary layer laminar. However, once the boundary layer becomes turbulent, it is almost impossible to return it to the laminar state by suction. A reduction in the form drag is possible by sucking away the boundary layer in the region of the trailing edge, while a reduction in the turbulent skin-friction drag is possible by blowing away the slowly moving air. In the region behind a suction slot the thinning of the boundary layer, when it is not in a laminar state, always increases the skin-friction drag and decreases the form drag. It has been observed experimentally that the nearer the suction slot is to the trailing edge, the less is the disadvantage of the increased skin-friction drag.
Performance
Published in Vaughn Nelson, Kenneth Starcher, Wind Energy, 2018
Vaughn Nelson, Kenneth Starcher
Boundary layer control describes all the methods that can be used to reduce skin friction drag by controlling the transition to turbulent flow, reducing the development of turbulent flow, and preventing separation of laminar and turbulent flows. Boundary layer control is intended to keep the flow attached further along the chord, thereby increasing lift and reducing drag and preventing dynamic stall—a hysteresis loop of lift caused by changing high angles of attack on blades that creates high loads.
Fundamentals of Fluid Mechanics
Published in Ethirajan Rathakrishnan, Instrumentation, Measurements, and Experiments in Fluids, 2020
The friction between the surface of the body and the fluid causes viscous shear stress and this force is known as skin friction drag. Wall shear stress τ at the surface of a body is given by () τ=μ∂Vx∂y
A computational study of biomagnetic fluid flow in a channel in the presence of obstacles under the influence of the magnetic field generated by a wire carrying electric current
Published in European Journal of Computational Mechanics, 2018
S. Morteza Mousavi, Mousa Farhadi, Kurosh Sedighi
In Figure 9, the influence of applying the magnetic field on the obstacle drag coefficient in the axial direction is shown. In this figure the values of are shown at different values of Mn, where is the obstacle drag coefficient in the absence of the magnetic field. With increasing the magnetic force the obstacle drag coefficient increases so that at Mn = 1.0 × 105 the obstacle drag coefficient increases by 22.14% compared to the obstacle drag coefficient in the absence of the magnetic field. The total drag comprises skin friction drag and pressure drag. Applying the magnetic field causes a downward flow leading to the reduction of the recirculation zone behind the obstacle. This phenomenon reduces the pressure drag, but applying the magnetic field increases shear stress significantly as Mousavi et al. (2016) reported. Therefore, the skin friction drag increases significantly. According to our results, in Re = 50, the increase of frictional drag outweighs the decrease of pressure drag.
Melting and entropy generation of infinite shear rate viscosity Carreau model over Riga plate with erratic thickness: a numerical Keller Box approach
Published in Waves in Random and Complex Media, 2022
Fuzhang Wang, Tanveer Sajid, Assad Ayub, Zulqurnain Sabir, Saira Bhatti, Nehad Ali Shah, Rahma Sadat, Mohamed R. Ali
Skin friction drag is caused by the viscosity of fluids and is developed from laminar drag to turbulent drag as a fluid moves on the surface of an object. Electric current in the presence of magnetic field generates a force termed as Lorentz force that depreciates the surface drag coefficient phenomenon.