Editing
Appendix/Ramblings/ToHadleyAndImamura
(section)
Jump to navigation
Jump to search
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
====For n = 3 Configurations==== Following §1.3 of Blaes85, let's specifically consider the case of slim PP-tori that have a polytropic index, <math>~n=3</math>. In this case, we have, <div align="center"> <table border="0" cellpadding="5" align="center"> <tr> <td align="right"> <math>~\mathcal{A}_\mathrm{Blaes}(\eta,\theta)</math> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~\frac{ (\beta m)^2}{2^6}\biggl[a_3(\eta,\theta)\biggr] \, , </math> </td> </tr> <tr> <td align="right"> <math>~\mathcal{B}_\mathrm{Blaes}(\eta,\theta)</math> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~\frac{(\beta m)^2}{2^6}\biggl[b_3(\eta,\theta)\biggr] \, , </math> </td> </tr> </table> </div> where, <div align="center"> <table border="0" cellpadding="5" align="center"> <tr> <td align="right"> <math>~a_3(\eta,\theta)</math> </td> <td align="center"> <math>~\equiv</math> </td> <td align="left"> <math>~\biggl\{ ~[8(n+1)\cos^2\theta - 3]\eta^2 (n+1) - (4n+1) \biggr\}_{n=3} </math> </td> </tr> <tr> <td align="right"> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~ ~2^2[2^5\cos^2\theta - 3]\eta^2 - 13 \, , </math> </td> </tr> <tr> <td align="right"> <math>~b_3(\eta,\theta)</math> </td> <td align="center"> <math>~\equiv</math> </td> <td align="left"> <math>~\biggl\{ [2^7\cdot 3(n+1)^3 \eta^2\cos^2\theta ]^{1/2} \biggr\}_{n=3} </math> </td> </tr> <tr> <td align="right"> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~[2^{13}\cdot 3\eta^2\cos^2\theta ]^{1/2}\, . </math> </td> </tr> </table> </div> <!-- OMIT Hence, the "constant phase locus" should be identified by the function, <div align="center"> <table border="0" cellpadding="5" align="center"> <tr> <td align="right"> <math>~m\phi_\mathrm{max}(\eta,\theta)</math> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~ \tan^{-1}\biggl\{ \frac{[2^3/(\beta m)]^2 + a(\eta,\theta) }{ b(\eta,\theta) } \biggr\} - k\theta </math> </td> </tr> <tr> <td align="right"> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~ \tan^{-1}\biggl\{ \frac{[2^3/(\beta m)]^2 - 13 + 2^2[2^5\cos^2\theta - 3]\eta^2 }{ 2^{6}(2\cdot 3)^{1/2}\eta \cos\theta } \biggr\} - k\theta \, , </math> </td> </tr> </table> </div> END OMIT --> Now, rather than examining the structural behavior of the amplitude and phase of the function, <math>~[W/W_0 -1]</math>, as we have done, above, Blaes evaluated the amplitude (only) of the function, <div align="center"> <math>~\frac{W}{W_0} = 1 + \mathcal{A}_\mathrm{Blaes}(\eta,\theta) + i \mathcal{B}_\mathrm{Blaes}(\eta,\theta) \, .</math> </div> For the specific case of <math>~n=3</math>, the square of the amplitude of ''this'' function is, <div align="center"> <table border="0" cellpadding="5" align="center"> <tr> <td align="right"> <math>~\biggl|\frac{W}{W_0} \biggr|_{n=3}^2</math> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~\biggl\{ 1 + \frac{ (\beta m)^2}{2^6}\biggl[a_3(\eta,\theta)\biggr] \biggr\}^2 + \biggl\{ \frac{(\beta m)^2}{2^6}\biggl[b_3(\eta,\theta)\biggr] \biggr\}^2 </math> </td> </tr> <tr> <td align="right"> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~1 + \frac{ (\beta m)^2a_3}{2^5} + \frac{ (\beta m)^4 }{2^{12}} (a_3^2 + b_3^2) </math> </td> </tr> <tr> <td align="right"> </td> <td align="center"> <math>~=</math> </td> <td align="left"> <math>~1 + \frac{ (\beta m)^2}{2^5} \biggl\{ 2^2[2^5\cos^2\theta - 3]\eta^2 - 13\biggr\} + \mathcal{O}[(\beta m)^4] \, . </math> </td> </tr> </table> </div> Therefore, to lowest order in the "slimness" parameter, <math>~\beta</math>, <div align="center"> <table border="0" cellpadding="5" align="center"> <tr> <td align="right"> <math>~\biggl|\frac{W}{W_0} \biggr|_{n=3}</math> </td> <td align="center"> <math>~\approx</math> </td> <td align="left"> <math>~1 + \frac{ (\beta m)^2}{2^6} \biggl\{ 2^2[2^5\cos^2\theta - 3]\eta^2 - 13\biggr\} \, . </math> </td> </tr> </table> </div> This (almost exactly) matches the amplitude expression derived by [http://adsabs.harvard.edu/abs/1985MNRAS.216..553B Blaes (1985)] and evaluated for the specific case of <math>~\beta = (101)^{-1/2}</math> — the relevant equation (1.12) from Blaes85 is digitally reproduced in the table that follows. <div align="center"> <table border="1" cellpadding="5" width="80%"> <tr><td align="center"> Equation (1.12) extracted without modification from p. 556 of [http://adsabs.harvard.edu/abs/1985MNRAS.216..553B Blaes (1985)]<p></p> "''Oscillations of Slender Tori''"<p></p> Monthly Notices of the Royal Astronomical Society, vol. 216, pp. 553-563 © Royal Astronomical Society </td></tr> <tr> <td align="center"> [[File:Blaes85Eq1.12.png|400px|center|Blaes (1985, MNRAS, 216, 553)]] <!-- [[Image:AAAwaiting01.png|400px|center|Whitworth (1981) Eq. 5]] --> </td> </tr> </table> </div> Our expression differs from the one published in Blaes85 in one detail: In Blaes85, the pre-factor of the second term inside the curly braces is, evidently, <math>~(\beta m)^2/2^5</math>, which is a factor of two larger than the corresponding pre-factor found in our expression. In our attempt to re-derive the Blaes85 expression (1.12), this extra factor of two disappears when we take the square-root of both sides to obtain the modulus, rather than the square of the modulus. Hopefully further reflection will resolve this discrepancy between our approximate expression for <math>~|W/W_0|_{n=3}</math> and the analogous one presented in Blaes85.
Summary:
Please note that all contributions to JETohlineWiki may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see
JETohlineWiki:Copyrights
for details).
Do not submit copyrighted work without permission!
Cancel
Editing help
(opens in new window)
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Log in
Namespaces
Page
Discussion
English
Views
Read
Edit
View history
More
Search
Navigation
Main page
Tiled Menu
Table of Contents
Old (VisTrails) Cover
Appendices
Variables & Parameters
Key Equations
Special Functions
Permissions
Formats
References
lsuPhys
Ramblings
Uploaded Images
Originals
Recent changes
Random page
Help about MediaWiki
Tools
What links here
Related changes
Special pages
Page information