User:Tohline/VE/RiemannEllipsoids
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SteadyState 2^{nd}Order Tensor Virial Equations
By satisfying all six — not necessarily unique — components of the SecondOrder Tensor Virial Equation, the entire set of Riemann Ellipsoids can be determined.
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Here we are only interested in determining the equilibrium conditions of uniformdensity ellipsoids that have semiaxes, .
General Coefficient Expressions
As has been detailed in an accompanying chapter, the gravitational potential anywhere inside or on the surface, , of an homogeneous ellipsoid may be given analytically in terms of the following three coefficient expressions:









where, and are incomplete elliptic integrals of the first and second kind, respectively, with arguments,

and 

[ EFE, Chapter 3, §17, Eq. (32) ] 
Adopted (Internal) Velocity Field
EFE (p. 130) states that the … kinematical requirement, that the motion , associated with , preserves the ellipsoidal boundary, leads to the following expressions for its components:









[ EFE, Chapter 7, §47, Eq. (1) ] 
Equilibrium Expressions
[EFE §11(b), p. 22] Under conditions of a stationary state, [the tensor virial equation] gives,



[This] provides six integral relations which must obtain whenever the conditions are stationary.
When viewing the (generally ellipsoidal) configuration from a rotating frame of reference, the 2^{nd}order TVE takes on the more general form:



[ EFE, Chapter 2, §12, Eq. (64) ] 
EFE (p. 57) also shows that … The potential energy tensor … for a homogeneous ellipsoid is given by



[ EFE, Chapter 3, §22, Eq. (128) ] 
where



[ EFE, Chapter 3, §22, Eq. (129) ] 
is the moment of inertia tensor.
The Three Diagonal Elements
For , we have,









Similarly, for ,






and, for ,






The Six OffDiagonal Elements
Notice that the offdiagonal components of both and are zero. Hence, the equilibrium expression that is dictated by each offdiagonal component of the 2^{nd}order TVE is,



For example — as is explicitly illustrated on p. 130 of EFE — for and ,




[ EFE, Chapter 7, §47, Eq. (3) ] 
whereas for and ,




[ EFE, Chapter 7, §47, Eq. (4) ] 
Given our adoption of a uniformdensity configuration whose surface has a precisely ellipsoidal shape and, along with it, our adoption of the above specific prescription for the internal velocity field, , we recognize that,
This has allowed us to set to zero one of the integrals in each of these last two expressions. In what follows, we will benefit from recognizing, as well, that,

Adding this pair of governing expressions we obtain,






[ EFE, Chapter 7, §47, Eq. (6) ] 
and subtracting the pair gives,






[ EFE, Chapter 7, §47, Eq. (7) ] 
Various Degrees of Simplification
Riemann SType Ellipsoids
Describe …
Jacobi and Dedekind Ellipsoids
Describe …
Maclaurin Spheroids
Describe …
Appendices: Various Integrals Over Ellipsoid Volume
Throughout this set of appendices, we work with a uniformdensity ellipsoid whose surface is defined by the expression,



Appendix A: Volume
Here we seek to find the volume of the ellipsoid via the Cartesian integral expression,



Preliminaries
First, we will integrate over and specify the integration limits via the expression,



second, we will integrate over and specify the integration limits via the expression,



third, we will integrate over and set the limits of integration as .
Carry Out the Integration
Following thestrategy that has just been outlined, we have,


















Appendix B: Coriolis Component u_{1}x_{2}






























[ EFE, Chapter 7, §47, p. 130, Eq. (9a) ] 
Appendix C: Coriolis Component u_{1}x_{3}
Here we will additionally make use of the integration limits,



Integration over the relevant Coriolis component gives,



























[ EFE, Chapter 7, §47, p. 130, Eq. (9b) ] 
Appendix D: The Other Four Coriolis Components
It follows that,






and,






and,






and,






Appendix E: Kinetic Energy Components
Looking first at the diagonal elements, we have,









See Also
© 2014  2020 by Joel E. Tohline 