PROOF OF THE UNIQUENESS OF THE HYDRODYNAMIC MASS TENSOR

Keyword(s):  
Author(s):  
Qiang Zhao ◽  
Hong Tao Wu

This paper describes two aspects of multibody system (MBS) dynamics on a generalized mass metric in Riemannian velocity space and recursive momentum formulation. Firstly, we present a detailed expression of the Riemannian metric and operator factorization of a generalized mass tensor for the dynamics of general-topology rigid MBS. The derived expression allows a clearly understanding the components of the generalized mass tensor, which also constitute a metric of the Riemannian velocity space. It is being the fact that there does exist a common metric in Lagrange and recursive Newton-Euler dynamic equation, we can determine, from the Riemannian geometric point of view, that there is the equivalent relationship between the two approaches to a given MBS. Next, from the generalized momentum definition in the derivation of the Riemannian velocity metrics, recursive momentum equations of MBS dynamics are developed for progressively more complex systems: serial chains, topological trees, and closed-loop systems. Through the principle of impulse and momentum, a new method is proposed for reorienting and locating the MBS form a given initial orientation and location to desired final ones without needing to solve the motion equations.


1983 ◽  
Vol 34 (3) ◽  
pp. 226-242 ◽  
Author(s):  
John A. Eaton

SummaryWhile it has long been known that added fluid mass may be important in the dynamics of parachutes, due to inadequate or incorrect derivation and/or implementation of the added mass tensor its full significance in the stability of parachutes has yet to be appreciated. The concept of added mass is outlined and some general conditions for its significance are presented. Its implementation in the parachute equations of motion is reviewed, and the equations used in previous treatments are shown to be erroneous. A general method for finding the equivalent external forces and moments due to added mass is given, and the correct, anisotropic forms of the added mass tensor are derived for the six degree-of-freedom motion in an ideal fluid of rigid body shapes with planar-, twofold- and axisymmetry, These derivations may also be useful in dynamic stability studies of other low relative density bodies such as airships, balloons, submarines and torpedoes. Full nonlinear solutions of the equations of motion for the axisymmetric parachute have been obtained, and results indicate that added mass effects are more significant than previously predicted. In particular, the component of added mass along the axis of symmetry has a strong influence on stability. Better data on unsteady forces and moments on parachutes are needed.


Physica ◽  
1966 ◽  
Vol 32 (1) ◽  
pp. 16-26 ◽  
Author(s):  
G. Kosály ◽  
G. Solt

2020 ◽  
Vol 95 (11) ◽  
pp. 115808
Author(s):  
Yanxing Song ◽  
Changchun Chai ◽  
Qingyang Fan ◽  
Wei Zhang ◽  
Yintang Yang
Keyword(s):  

1967 ◽  
Vol 22 (12) ◽  
pp. 2086-2096
Author(s):  
Udo Hübner

The four matrices of the electrical and the energy current densities are derived for bismuth-Telluride in arbitrary magnetic fields on the basis of DRABBLE'S six-ellipsoid-model. The scattering time will be taken anisotropic but not necessarily diagonal in the same system as the mass tensor. The starting point is BOLTZMANN'S transport equation in its region of validity. These four matrices are converted to resistance, absolute thermopower, PELTIER coefficient and electronic part of the heat conductivity for vanishing magnetic field and for magnetic fields parallel to the trigonal and the binary axis of the crystal. Saturation formulas for all directions of the magnetic field are deduced. Four resistance components mesured in dependence of the magnitude of the magnetic field are used to evaluate the band parameters which are different once more from data of DRABBLE and TESTARDI; but they are independent of the magnitude of the magnetic field within the limit of error.


Universe ◽  
2019 ◽  
Vol 5 (8) ◽  
pp. 188 ◽  
Author(s):  
Volkmar Putz

A non-relativistic theory of inertia based on Mach’s principle is presented as has been envisaged, but not achieved, by Ernst Mach in 1872. The central feature is a space-dependent, anisotropic, symmetric inert mass tensor. The contribution of a mass element d m to the inertia of a particle m 0 experiencing an acceleration from rest is proportional to cos 2 α , where α is the angle between the line connecting m 0 and d m and the direction of the acceleration. Apsidal precession for planets circling around a central star is not a consequence of this theory, thereby avoiding the prediction of an apsidal precession with the wrong sign as is done by Mach-like theories with isotropic inert mass.


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