Showing papers on "Bernoulli's principle published in 1969"

Plane Subcritical Flow Past a Lifting Aerofoil

Abstract: A method for solving the equations of steady two-dimensional inviscid isentropic irrotational flow past an obstacle is presented. The exterior of the obstacle is mapped on the interior of a circle, any sharp edge being taken into consideration, so that the far flow with circulation becomes an oriented dipole and vortex. The stream function is introduced and these two singularities are removed to leave a modified stream function which is finite everywhere; the differential equation which it satisfies is represented by a difference scheme on an annular mesh inside the circle. Provided that the flow is everywhere subsonic (subcritical problem), the iterative method of solution of this and Bernoulli’s equation is convergent. Results illustrating the method are presented for the 20% ellipse and the 10% R. A. E. 101 section, at zero and non-zero incidence.

Bernoulli potentials in superconductors

Abstract: A relation between the Bernoulli potential in a superconductor and the Meissner current is developed from thermodynamic arguments. The relation is used to obtain the temperature dependence of the potential. For a pure superconductor at the absolute zero the result agrees with that of Adkins and Waldram. For an isotropic superconductor at a finite temperature, the potential is proportional to the parameter partial differential ρs/partial differential ρ.

Gradually Varied Flow

Abstract: 2.1.1 General. Gradually varied flow is non-uniform flow in which the change of depth in the channel occurs but gradually, in the direction of flow. As a result the streamlines in any restricted locality can be considered straight and parallel and the resulting pressure distribution will therefore be hydrostatic. This restriction on the flow conditions also enables the Bernoulli equation to be used to evaluate the fluid energy. It is known that the Bernoulli equation, as well as the hydrostatic pressure distribution, breaks down when the streamlines become significantly curved. The criterion of streamline curvature will be used to distinguish between gradually varied flow and rapidly varied flow although in practice the exact point of distinction is indeterminate.

Bernoulli effect fluid pressure convertor, switch, amplifier and the like

Abstract: A means for controlling the pressure of a fluid output signal in accordance with the pressure of a fluid input signal applied to a Bernoulli air bearing. The bearing issues a fluid stream to provide a fluid cushion having an adjustable positive or negative pressure (relative to ambient) between the nozzled frontal surface of the bearing and a movable member, which member operates as a valve or restriction to control the pressure and flow rate of the fluid output signal as a function of the pressure of the fluid input signal.

Development and evaluation of a second-order wave-resistance theory.

Abstract: : A new second-order wave-resistance theory for floating bodies is developed, and then assessed by application to a parabolic strut. The problem is treated as a potential flow problem with a centerplane distribution of sources to represent the body. However, the kinematical boundary condition is satisfied on the surface of the body. It is supposed that the beam-length ratio , t , is small and that the square of the disturbance velocities which appeared in Bernoulli's equation on the free surface is given in terms of the components of the first-order potential. It is also assumed that the solution of the source density, sigma, is in the form of an asymptotic series in t , and the solution for sigma is obtained up to the order of t sq. The wave resistance is then computed on the basis of the improved source density and the correction arising from the improved representation of the free surface. It is found that at low Froude number the expansion scheme used by Sisov, by Maruo, by Yim, and by Eggers, can give negative resistance if the beam-length ratio is not small enough. Therefore, a new definition is adopted; that is, the second-order wave resistance is based on the improved disturbance potential without expansion of the amplitude function of the wave-resistance integral. (Author)

On the use of Bernoulli's equation as a comparison equation in stability problems

Abstract: Sufficient conditions for finding stability regions are derived. The stability approach is based on the comparison theorems using Bernoulli's scalar comparison equation.