As an application of quantum fluid mechanics, we consider the drag force exerted on a sphere by an ultradilute gas. Quantum mechanical diffraction scattering theory enters in that regime wherein the mean free path of a molecule in the gas is large compared with the sphere radius. The drag force is computed in a model specified by the "sticking fraction" of events in which a gaseous molecule is ...

The effects of radiation drag force on the structure of relativistic electronpositron and electron-proton outflows are considered within the one-fluid approximation. It is shown that for a magnetically-dominated outflow the drag force does not change the particle energy inside the fast magnetosonic surface. In this region the action of the drag results in a diminishing of the Poynting flux, not...

Understanding how the shape and motion of an aquatic animal affects the performance of swimming requires knowledge of the fluid forces that generate thrust and drag. These forces are poorly understood for the large diversity of animals that swim at Reynolds numbers (Re) between 10(0) and 10(2). We experimentally tested quasi-steady and unsteady blade-element models of the hydrodynamics of undul...

We present a combined experimental and theoretical study of the drag force acting on a high porosity aerogel immersed in liquid (3)He and its effect on sound propagation. The drag force is characterized by the Knudsen number, which is defined as the ratio of the quasiparticle mean free path to the radius of an aerogel strand. Evidence of the Knudsen-hydrodynamic crossover is clearly demonstrate...

For advanced atomic force microscopy (AFM) investigation of chemical surface modifications or very soft organic sample surfaces, the AFM probe tip needs to be operated in a liquid environment because any attractive or repulsive forces influenced by the measurement environment could obscure molecular forces. Due to fluid properties, the mechanical behavior of the AFM cantilever is influenced by ...

This review analyses rowing by linking the biological and mechanical systems that comprise the rowing system. Blade force was found to be the only propulsive force to counter the drag forces, consisting of both air drag and hydrodynamic drag, acting on the system. Vertical oscillations of the shell are shown to have minimal impact on system dynamics. The oar acts as the link between the force g...

abstract: in this paper, optimization of boeing 747 wing has been accomplished for cruise condition (mach number=0.85, flight altitude=35000 ft), where an optimal wing shape is proposed. objective functions are minimization of wing weight and drag force that as well as confining design parameters, two functional constrains are applied. the first functional constrain is fuel tank volume in the a...

Inertial microfluidics-based devices have recently attracted much interest and attention due to their simple structure, high throughput, fast processing and low cost. They have been utilised in a wide range of applications in microtechnology, especially for sorting and separating microparticles. This novel class of microfluidics-based devices works based on intrinsic forces, which cause micropa...

We present a simple method of measuring viscous drag force on particles in microfluidic environment. Using in-situ polymerization, the effect of particle size and shape on viscous drag force is directly measured, which is crucial to understand motion of microbodies in low Reynolds numbered flow.

Numerical investigation was performed on NACA 0015 which is a symmetric airfoil. Pressure distribution and then lift and drag forces are verified. Changing of ground clearance was a considerable point. Also the angle of attack was changed from 0° to 10°. Pressure coefficient reaches its higher amounts on the wing lower surface when the ground clearance diminishes. Increment of the angle of atta...