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The general equation, as given on the page, is not very general, as it does not apply to cases with non-constant pressure or fluid density. Sampo Smolander (talk) 21:38, 27 March 2013 (UTC)
That's not exactly true: as for pressure (you consider fluid flow, I guess), is simply , while the actual quantity being transported is the momentum, namely ( but that's N-S equations or Euler or something else in any case). The only missing feature is the possible dependence of the reaction term on the variable, namely should be indicated as . Dvd7587 (talk) 13:32, 8 June 2013 (UTC)
No no. Solubility of a gas in a liquid depends on pressure, so in the presence of a pressure gradient (a water column in a lake, for example, hydrostatic pressure) you cannot just take the derivative of concentration to see to which direction diffusion is supposed to go. Sampo Smolander (talk) 06:56, 29 August 2015 (UTC)
The general equation is always a start point for numerical solution. However, it is more useful to develop the equation in some other condition for better engineering application.GraceChen117 (talk) 20:51, 26 April 2017 (UTC)
Having these equations written in index notation as well as having the vector notation would be helpful. Many times when you see the advection-diffusion equation it is written in index notation. Conor murphy (talk) 19:53, 26 April 2017 (UTC)