On the Non-Linear Theory of the Employment Cycle

1967 ◽  
Vol 34 (2) ◽  
pp. 153 ◽  
Author(s):  
H. Rose
Keyword(s):  
Linear Theory ◽  
Non Linear ◽  
Employment Cycle

A non-linear theory for a full cavitating hydrofoil in a transverse gravity field

1967 ◽  
Vol 29 (2) ◽  
pp. 317-336 ◽  
Author(s):  
Bruce E. Larock ◽  
Robert L. Street
Keyword(s):  
Gravity Field ◽  
Linear Theory ◽  
Mixed Boundary ◽  
Linear Method ◽  
Two Dimensional ◽  
Mixed Boundary Value Problem ◽  
Cavity Model ◽  
Cavity Size ◽  
Non Linear ◽  
Cavitating Hydrofoil

An analysis is made of the effect of a transverse gravity field on a two-dimensional fully cavitating flow past a flat-plate hydrofoil. Under the assumption that the flow is both irrotational and incompressible, a non-linear method is developed by using conformal mapping and the solution to a mixed-boundary-value problem in an auxiliary half plane. A new cavity model, proposed by Tulin (1964a), is employed. The solution to the gravity-affected case was found by iteration; the non-gravity solution was used as the initial trial of a rapidly convergent process. The theory indicates that the lift and cavity size are reduced by the gravity field. Typical results are presented and compared to Parkin's (1957) linear theory.

Non-Linear Theory of Heteropolar Electrical Machines

1965 ◽  
Vol AS-3 (2) ◽  
pp. 32-38 ◽  
Author(s):  
S. V. Ahamed ◽  
E. A. Erdelyi ◽  
R. E. Hopkins
Keyword(s):  
Linear Theory ◽  
Electrical Machines ◽  
Non Linear

scholarly journals Non-linear evolution of the resonant drag instability in magnetized gas

2019 ◽  
Vol 485 (3) ◽  
pp. 3991-3998 ◽  
Author(s):  
Darryl Seligman ◽  
Philip F Hopkins ◽  
Jonathan Squire
Keyword(s):  
Linear Theory ◽  
Coherent Structures ◽  
Magnetic Energy ◽  
Density Fluctuations ◽  
Linear Evolution ◽  
Drag Forces ◽  
Non Linear ◽  
Magnetohydrodynamic Simulations ◽  
First Time ◽  
Different Parts

Abstract We investigate, for the first time, the non-linear evolution of the magnetized ‘resonant drag instabilities’ (RDIs). We explore magnetohydrodynamic simulations of gas mixed with (uniform) dust grains subject to Lorentz and drag forces, using the gizmo code. The magnetized RDIs exhibit fundamentally different behaviour than purely acoustic RDIs. The dust organizes into coherent structures and the system exhibits strong dust–gas separation. In the linear and early non-linear regime, the growth rates agree with linear theory and the dust self-organizes into 2D planes or ‘sheets.’ Eventually the gas develops fully non-linear, saturated Alfvénic, and compressible fast-mode turbulence, which fills the underdense regions with a small amount of dust, and drives a dynamo that saturates at equipartition of kinetic and magnetic energy. The dust density fluctuations exhibit significant non-Gaussianity, and the power spectrum is strongly weighted towards the largest (box scale) modes. The saturation level can be understood via quasi-linear theory, as the forcing and energy input via the instabilities become comparable to saturated tension forces and dissipation in turbulence. The magnetized simulation presented here is just one case; it is likely that the magnetic RDIs can take many forms in different parts of parameter space.

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