After reading Wikipedia articles on advection and convection, I still cannot determine whether there is a consensus on a difference between these two terms. Sometimes, the term convection seems to include advection and diffusion, sometimes not.

convection = diffusion + advection. That is, convection is the sum of fluid movement due to bulk transport of the media (like the water in a river flowing down a stream - advection) and the brownian/osmotic dispersion of a fluid constituent from high density to lower density regions (like a drop of ink slowly spreading out in a glass of water - diffusion).

Apr 1, 2018 · Whereas advection is the transport of a substance by bulk motion;that is the movement of fluids down a pressure or temperature gradient. My confusion is that: when there is a high concentration of some quantity, doesn't that mean also a high pressure of this quantity ? This thought makes me see diffusion and advection the same..

Jan 20, 2015 · Your math is correct, (u ⋅ ∇)u ≡ u ⋅(∇u) (u ⋅ ∇) u ≡ u ⋅ (∇ u). This should make sense because the commutative property holds for dot products. Personally, I prefer to view u ⋅ ∇ u ⋅ ∇ as an operator that acts on something (in this case, a vector, but it could be a scalar or higher tensor as well). Thus, I would use (u ⋅ ∇)u (u ⋅ ∇) u over the other way ...

Apr 13, 2021 · For a 3D flow, the advection term in the x-momentum equation is −∇ ⋅ (ρuu ) − ∇ ⋅ (ρ u u →). How does momentum flow in the y and z directions contribute to the momentum flux in the x direction?

where ϕ ϕ is property per unit mass, u u → is velocity vector and Γ Γ is diffusive term (Like viscosity or thermal conductivity). What I can't understand is the use of the terms "convective" and "diffusive"? What do they mean? What is the physical interpretation of these terms? Their dictionary meanings seem to exacerbate the situation: …

Diffusion is an important concept in elementary science education, especially because it supports (or seems to support) the notion of matter consisting of very small everyday particles (as opposed ...

Jul 19, 2020 · Context: Consider the advection-diffusion equation with periodic boundary conditions (PBC) over a flat square domain L × L. The scalar density ρ is transported by a prescribed field v = − ∇U, where U(x) is a scalar potential that has …

Now with regards to the actual question, how can we show that this is an advection equation. Advection simply is the transport of some material along a fluid flow.

Oct 30, 2021 · In this Wikipedia article, specifically in the section "Mathematics of advection", the following general equation for advection is given as: \begin {equation} \dfrac {\partial\psi} {\partial...