User talk:Arthurv~enwiki

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Linearized Euler equations

Hello Arthurv. Thank you for your contributions to the Euler equations article. However, I have some problems with the full jacobians you added, since:

the given jacobians are for a special equation of state used, so they are less general than the rest of the article,
the symbol H appears both as enthalpy and as one of the fluxes,
some other variables are also named not in according with the rest of the article (E, V).

Are you willing to change these? If not, I can do it. You can respond either below, or otherwise on my talk page if you wish. Best regards, Crowsnest (talk) 09:00, 26 March 2008 (UTC)[reply]

Variables

Thanks for the comments. I've posted on your talk page, but i'll post here as well. I do see that the variables can duplicate (E,V, H), however enthalpy is usually given as H in many textbooks, as well as E for total energy...I guess there's a global shortage of symbols =/

However you're free to change it if you wish - my opinion is that it would be less confusing to change the symbols for the fluxes (F,G,H) than enthalpy (which is usually given as H) since many textbooks only demonstrate the Euler equations in 1 or 2 dimensions, not 3 dimensions as I've included. Thanks again for your help,

Arthurv (talk) 12:16, 26 March 2008 (UTC)[reply]

Hi Athurv. I agree that the fluxes should be renamed, rather than the enthalpy. I will give it a try.

Further, it is common on Wikipedia to react directly under the question or last reaction to a question (unless the owner of the talk page requests otherwise). Indentation can be used to indicate on which (level of) remarks and questions the new contribution is made. See WP:TALK. Crowsnest (talk) 16:58, 26 March 2008 (UTC)[reply]

Ok, got it. I'm thinking of expanding the section on the solutions of the Euler equations being waves (by showing how the linearized euler equations can be transformed into wave equations) but it's more convenient to only show it in 1 dimension. Do you think it belongs in the article or should it go elsewhere? Arthurv (talk) 18:02, 26 March 2008 (UTC)[reply]

I renamed the fluxes and jacobians, to prevent conflicting variable names. But on inspection of the jacobians, I think they may contain some typographical errors: there must be certain symmetries between x, y and z-directions, and some entries seem inconsistent with others. Can you further add a reference to the article, where you found the jacobians? In my opinion, an extension with waves in 1D-Euler will fit nicely into the article (perhaps another sub-section of "Linearized Euler equations ?). Crowsnest (talk) 21:20, 26 March 2008 (UTC)[reply]

Sorry, the typos were due to me copying, pasting and modifying the first matrix LaTeX code to make the 2nd and 3rd matrices! I've made some corrections and tried to make the notation a bit neater to make it easier to spot errors. Thanks for notifying me. My primary source is E.F Toro, Riemann Solvers and Numerical Methods for Fluid Dynamics 2nd edition (I've added it to the references). That's where I got the x-direction jacobian from, however I derived the y- and z-direction matrices myself. Since the transformation to wave equations involves the jacobians, as you suggested, I'll move the "shock waves" section under the Linearized equations section. Arthurv (talk) 01:23, 27 March 2008 (UTC)[reply]

Great. But I would not move the shock waves under the Linearized Euler equations, since they are essentially non-linear. Crowsnest (talk) 07:58, 27 March 2008 (UTC)[reply]

Ok, I'll move shock waves after Linearized equations? Because the shock waves develop once the characteristic lines intersect. Arthurv (talk) 10:02, 27 March 2008 (UTC)[reply]

I made much bigger errors on Wikipedia than the typographical errors you left in the jacobians.

About the shock waves: if I understand correctly, you intent to apply the method of characteristics to the 1D Euler equations in the form with the jacobians. Is that with linearized or with non-linear jacobian? Because on that it depends very much where to put the shock waves. If you intent to use the non-linear jacobian in your characteristics determination, the shock waves come afterwards (but then my question is: what do you mean with linearized jacobians?). If you use a linearized jacobian, I would put the shock waves first. Crowsnest (talk) 19:11, 27 March 2008 (UTC)[reply]

I did some resectioning, maybe that is of any help to you. Crowsnest (talk) 20:06, 27 March 2008 (UTC)[reply]

Thanks for your assistance - I'm trying to get my notes organized before I put them on. Getting the Jacobians transforms the Euler equations from nonlinear to quasi-linear, since the jacobian is still a function of the state variables. If taken against a reference state, as you said, they become linear and can be used to transform the equations into wave equations. This is because the Jacobian is diagonalizable, with real, linearly independent eigenvectors (as long as sound speed is positive). I'll put it up shortly. Arthurv (talk) 00:35, 28 March 2008 (UTC)[reply]

User subpage

Hi Arthurv. If you like to, you can also put things you are working on in a user subpage, see How do I create a user subpage?. Best regards, Crowsnest (talk) 22:24, 3 April 2008 (UTC)[reply]

Thanks, I've followed your advice and have started creating subpages. Arthurv (talk) 01:31, 4 April 2008 (UTC)[reply]

I saw you started an article on Roe solvers. Great! If it is of a more mature form, e.g. having an introductory heading, links and references, the ~~sjablones~~ templates on top can be removed. Crowsnest (talk) 08:19, 4 April 2008 (UTC)[reply]

To avoid people putting all these templates, you can place yourself the template Template:Underconstruction on top of the page, when creating the new page, so people know you are working on it, see here for more information. Otherwise, someone may think its is not worthwhile for Wikipedia, and recommend your rudimentary article for deletion, see WP:AfD. I myself edit a new article on a subpage of my user page, and only create the new article when I think it mature enough to survive on Wikipedia.

I would leave the templates on top of the page as they are now, and remove them when you think the article is mature enough, e.g. has an introductory header, links and references. Best regards, Crowsnest (talk) 08:43, 4 April 2008 (UTC)[reply]

Speedy deletion of Image:Img 5655.jpg

A tag has been placed on Image:Img 5655.jpg requesting that it be speedily deleted from Wikipedia. This has been done under section I1 of the criteria for speedy deletion, because the image is an unused redundant copy (all pixels the same or scaled down) of an image in the same file format, which is on Wikipedia (not on Commons), and all inward links have been updated.

If you think that this notice was placed here in error, you may contest the deletion by adding {{hangon}} to the top of the page that has been nominated for deletion (just below the existing speedy deletion or "db" tag), coupled with adding a note on [[ Talk:Image:Img 5655.jpg|the talk page]] explaining your position, but be aware that once tagged for speedy deletion, if the article meets the criterion it may be deleted without delay. Please do not remove the speedy deletion tag yourself, but don't hesitate to add information to the article that would would render it more in conformance with Wikipedia's policies and guidelines. ^┌_Joshii^┐_└^chat_┘ 04:10, 22 November 2008 (UTC)[reply]

Your account will be renamed

Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Arthurv. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Arthurv~enwiki that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name. If you think you might own all of the accounts with this name and this message is in error, please visit Special:MergeAccount to check and attach all of your accounts to prevent them from being renamed.

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Sorry for the inconvenience.

Yours,
Keegan Peterzell
Community Liaison, Wikimedia Foundation

22:13, 19 March 2015 (UTC)

Renamed

This account has been renamed as part of single-user login finalisation. If you own this account you can log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: Special:GlobalRenameRequest. -- Keegan (WMF) (talk)

10:41, 22 April 2015 (UTC)