Talk:Convection–diffusion equation

Wiki Education Foundation-supported course assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 25 February 2020 and 8 May 2020. Further details are available on the course page. Student editor(s): Alexis291.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 18:25, 16 January 2022 (UTC)

Given general equation not general

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), $R$ is simply $\nabla p$, while the actual quantity being transported is the momentum, namely$\rho v$ ( 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 $R$ should be indicated as $R(c)$. 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)

Index Notation

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)

Merge with Smoluchowski equation and Generic scalar transport equation

All of these articles are about the the same equation [albeit slightly different terminology and notation]. OK to merge? --Steve (talk) 13:52, 18 April 2012 (UTC)

Perhaps merge Convection–diffusion equation + Smoluchowski equation, but leave Generic scalar transport equation alone, since the first two are more physical, the third is more mathematical...

Also the first two are more closley about diffusion, but the general transport equation is about transport in general. F = q(E+v×B) ⇄ ∑_ic_i 15:16, 18 April 2012 (UTC)

On second thought forget that - just merge them. F = q(E+v×B) ⇄ ∑_ic_i 15:21, 18 April 2012 (UTC)

Done --Steve (talk) 20:01, 20 April 2012 (UTC)

Nice work - I hadn't notice till now. F = q(E+v×B) ⇄ ∑_ic_i 15:27, 21 April 2012 (UTC)

New rating, potential improvements

Hello everyone, as you can see I rerated this article to C-class. I'm not totally sure that's appropriate, I just knew it's definitely not start class anymore which is how it was labeled. This is what the article looked like when it was rated start class in Feb 2010. As you can see it has come a long way.

These were ideas I had for potential improvements to this page:

• Combining "Smoluchowski convection-diffusion equation" and "As a stochastic differential equation" sections
• Create "application" section (parent to "in biology", "in semiconductor physics" at least).
• More introduction or clarity for "As a stochastic differential equation" section
• Tone in "Similar equations in other contexts"
• Improve "numerical solution" - providing either more clarity and introduction or nothing at all. As it stands it might be a bit confusing that this only talks about how they are solves (pen and paper vs computer) and not an overview of what the solutions themselves are.

I'm adding this here in case anyone has thoughts on these proposed changes, or wanted to make them themselves. And if not I hope I can get around to it. Thanks! IllQuill (talk) 21:20, 15 January 2021 (UTC)

Image

I have no idea what the figure is illustrating. The caption says it is "As carriers are generated due to light shining at the center of an intrinsic semiconductor...", but this cannot be accurate, since carriers are photo-generated as electron/hole pairs, and thus the total number of electrons must equal the number of holes.

Also, what are the time steps of the animated GIF?Geoffrey.landis (talk) 21:25, 22 November 2021 (UTC)