User talk:Evilmathninja

Hi,

I have read your article on aeroacoustics and I am afraid some points are not fully correct. Would you prefer me to explain you which ones or would you prefer that I correct what is wrong directly in the wiki? The main error is when you say that Lighthill's equation is an approximation: in contrary it is just a reformulation of the Navier-Stokes equations, with no approximation nor simplification. Note however that what you are writing in your text is a simplified version of the Lighthill's formulation of the 52's paper: you should not make so many approximations that soon if you want things to stay general enough (saying for example that Tij=rho ui uj is only valid in certain cases). Also, some additional references could be added.

Thanks in advance for your answer, Best regards

Hi! It is good to get feedback. Of course if something is incorrect you are free (and should!) correct it. However, I am afraid that I do not get your point. In the discussion of Lighthill's equation I do explicitly (in bold letters!) say that is in an exact equation. In the following section two other equations are given, which are approximate. There is no way that they can be exact because both derivation (the one on the wiki and the one in Landau and Lifshitz's book) assume certain linear relations hold true. Those might be very well justified and work in practice but they are certainly no longer exact. Only equation (*) is exact. Hope that answers your question. :) Evilmathninja 17:39, 19 January 2007 (UTC)