Questions tagged [transport-phenomena]

Transport phenomenon are mechanisms by which particles or quantities move from one place to another. For example, this could be electrical transport (where electrical charge moves), thermal transport (where thermal energy moves), or molecular diffusion (where mass moves).

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Convective heat transfer using a small parameter expansion of the heat equation

I'm trying to follow along with this paper on perturbative transport analysis. The section I'm stuck on analyzes the heat equation in 1D slab geometry. To get a diffusion-only solution is relatively ...
12 views

Moment transport in fluid, when $(v_x,v_y,v_z) = (by,0,0)$

Consider a fluid, where the velocity of the fluid has components $$(v_x,v_y,v_z) = (by,0,0)$$ where $b$ is a constant. We can use Newton's law of viscosity to determine the flux of momentum in this ...
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How to determine qualitatively the metallic/semimetallic conduction behaviour by comparing chemical potential and thermal energy?

Suppose a material has a semi-metallic dispersion and we want to study electronic transport with small applied electric and magnetic field. Let the chemical potential be positive-valued (i.e. the ...
61 views

Molecular explanation for pressure

According to this post, viscous stress is the result of molecular diffusion. More specifically, it's a transfer of momentum in a direction perpendicular to the direction of a velocity gradient. This ...
50 views

Is momentum flux scalar or vector?

I'm trying to derive Navier Stokes equation and stacked the linear momentum equation below. The second term is momentum flux, but it seems scalar value for me because it is vector times vector. How ...
29 views

Modelling electrical conductivity in low-dimensional nanostructures

I know that the Boltzmann transport equation can be solved under the Relaxation Time Approximation (RTA) to obtain the electrical properties of materials. However, the parameter that I am interested ...
41 views

Is my understanding of Seebeck effect correct?

I'm not sure whether I understand thermoelectric voltages (Seebeck effect). In the following image I show a simple thermo-couple consisting of materials A and B. On the left side there is a ...
29 views

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 t}+...
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Question on the calculation of the flux of a subtance at a point across any surface

How would one notate the operation leading to Eqn(1)? The flux of a substance at a point $P$ is represented by the vector $f_i$, and its vector components ($\vec f_x,\vec f_y,\vec f_z$) are the fluxes ...
If there is no limit to $ZT$, why are there no materials with $ZT>3$?
It is well understood that the thermoelectric performance of a material (described by the parameter $ZT$ ) has no transport related upper theoretical bound. This means a material can exist that can ...