Transport Definition and 265 Threads

Homework Statement In the book, Nuclear Reactor Theory, Glasstone, Bell, under section 2.2 SOLUTION OF THE ONE-SPEED TRANSPORT EQUATION BY THE SEPARATION OF VARIABLES, I have difficulty in understanding the derivation. Hope some one can explain the derivation or give a reference where the...

Hi, I'm having some trouble wrapping my head around some of the concepts and language of charge transport in Photovoltaic cells (and thus pn-diodes). My biggest problem is understanding the role played by the emitter region vs. the depletion region. In a typical PV cell the front emitter...

Since for a general contravariant vector, ##\nabla_{\nu}V^{\mu}## will not in general be zero, is it correct to say that all of them are transported by Fermi Transport? (With the only vector being parallel transported being the four velocity vector?)

I'm currently in a GR class and have come across the notion of parallel transport, and I've searched and searched the last few days to try and understand it but I just can't seem to wrap my head around it, so I'm hoping someone here can clarify for me. The way I picture parallel transport is...

I've managed to derive the form of Reynolds transport theorem as a bilance of linear momentum of the system: \left (\frac{\vec{\mathrm{d} p}}{\mathrm{d} \tau} \right )_{system}=\frac{\mathrm{d} }{\mathrm{d} x}(\int_{V}^{ }\vec{v}\cdot \rho dV)+\int_{A}^{ }\vec{a}dm+\int_{A}^{ }\vec{v}\cdot \rho...

I cannot understand the the relation between Reynolds Transport Theorem and Volume Calculation. Volume calculation is an simple, straightforward process which, I think, have much connection between Reynolds Transport Theorem. We calculate volumes in thermodynamics, heat transfer and fluid...

The recent thread on parallel transport has raised a couple of things I'd like to review for my own sake. I'll address them one at a time as my time permits. The first question is this. If we offer ##t^a \nabla_a u^b## or the equivalent ##\nabla_{\vec{t}} u^b## as the definition of parallel...

Good Day Guys, I need help in checking the beam size required to transport a cargo. What checks do i do? 1. Check actual BM with resisting moment of the beam 2. Check actual shear with the resisting moment of the beam How do i calculate following if I only know the type of beam used, i.e...

Background: I am taking an undergraduate fluid mechanics class. I seem to have a misunderstanding with my interpretation of Reynolds Transport theorem (RTT), which I have written below: $$\frac{DB_{sys}}{Dt} = \frac{\partial}{\partial t}\int_{CV}\rho bd V +\int_{CS}\rho b \vec{V}\cdot...

Homework Statement [/B] I am given the configuration below of a membrane and it is said that Na+ ions are transported actively through transporters from the inside to the outside. The J_Na_a seen below is the active current density of the Na ions and it is constant. Vm is the potential...

One thing I find frustrating when trying to get a handle on this theorem is the number of different forms presented in the literature. I understand this to be due to it being very general theorem applicable to many different contexts. Not that the world needs a new, slightly different looking...

Hello everyone ! I wanted to ask you if anyone ever encountered problems with proton transport using MCNP. In particular, the production of electrons when protons interact with matter. I have been trying to figure it out modifying the different physics cards (phys, lca, ...) with no result...

Hey guys, I need your help. We tried to derive the ekman transport in a lecture. The assumptions we made are 1. constant density 2. stationarity 3. no horizontal pressure gradient and no horizontal velocity gradient 4. no vertical velocity. So this is what the professor showed us: But is...

Hey guys, I got this problem: We had the derivation of the ekman transport today in class. And what I wondered about is this: Usually the equation for the ekman transport looks similar to this (depends on the author) u = V_0 e^{az} cos(\frac{\pi}{4}+az) v = V_0 e^{az} sin(\frac{\pi}{4}+az)...

Hello, I have 2 questions regarding similar issues : 1*) Why does one say that parallel transport preserves the value of dot product (scalar product) between the transported vector and the tangent vector ? Is it due to the fact that angle between the tangent vector and transported vector is...

Hello! I try to think about the Foucault pendulum with the concept of parallel transport(if we think of Earth as being a perfect sphere) but I can't quite figure out what the vector that gets parallel transported represents(for example, is it the normal to the plane of oscillation vector?). In...

I learned about Tesla's valve and how, without moving parts, it wouldn't be useful enough. But my question is, can I make a pipe with the valve's structure, and only apply heat in order to create flow. I know things follow the path of least resistance, and with a constant addition of heat, I'm...

Hello, I'm studing the history of this phenomenon. Does someone has the original paper of A.G. Walker of 1932?

Hi there, I am always confusing in the difference between diffusive and ballistic transport. My understanding on the diffusive transport is from it's name, particles diffuse from the high density region into the low density region. I think the diffusion happens towards all direction, is it why...

I'd like to purchase one of these books for self-study. The BSLK Introductory Transport Phenomena claims: "Devoting more space to mathematical derivations and providing fuller explanations of mathematical developments—including a section of the appendix devoted to mathematical topics—allows...

I know Mars colonization is a hot topic these days, and there are a lot of threads on this topic, but I would like to discuss specifically the SpaceX Interplanetary Transport System. There's a video on the subject here. On a recent thread that I posted here, some people came to the conclusion...

Elon Musk presented SpaceX's plans for its manned missions beyond Earth orbit yesterday. SpaceX is well known for missing their deadlines (like most in the space industry, to be fair), so we'll see how long it will take to develop it. The question how it will look like is clearer already, here...

Hello, When looking at the simplest definition of mechanical devices, is there a way to transport something non-mechanically? Physics isn't my strong suit, but it seems to me that all transport is mechanical in nature. The phrase 'mechanical transport' comes up a lot in political discussions...

A free electron gas would have zero magnetoresistance; it takes two carrier types to get ordinary magnetoresistance, which is always positive in sign. Beal-Monod and Weiner explain the negative magnetoresistance found in very dilute magnetic alloys, in terms of the spin-flip scattering of...

I have to say first that I found quite a similar question under https://www.physicsforums.com/threads/poynting-vector-dilemma.331375/ However those thread ended without real answer.There shall be the following simple setup: A battery, and quite at a distance a light bulb. They are connected by...

i am a physicist now i am doing Ms in nuclear engineering ... i need to understand basic concepts ... neutron transport equation ? what is the transport phenomenon actually ? and pressure drop calculations in core ... please help thanks in advance

hi, first of all in this image there is a fact that we have parallel transported vector, and covariant derivative is zero along the "pr"path as you can see at the top of the image. I consider that p, and r is a point and in the GREEN box we try to make a taylor expansion of the contravariant...

Homework Statement Explain why large transport trucks have a hard steel barrier between the load and the driver's cab. Consider Newton's first law in your answer. Homework Equations no equations required.The Attempt at a Solution According to Newton’s first law, if no net force acts on an...

Homework Statement Homework Equations one dimensional Reynold's transport theorem The Attempt at a Solution [/B] I started with this equation, and tried to expand it using the equation given in #2. This is the farthest I have gotten so far. I got stuck from here. I do not know how to...

Homework Statement Which of the following is/are true regarding glucose transport to the brain? There could be multiple answers. a) Glucose uptake by the nerve cells of the brain is dependent on insulin b) Greater concentrations of glucose in the blood should increase the rate at which glucose...

I'm in a logical loop here: 1. A tensor undergoes parallel transport if, as it moves through a manifold, its covariant derivative is zero. 2. Covariant derivative describes how a tensor changes as it moves through a manifold. 3. A tensor undergoes change as it moves if it does not parallel...

Hi, Could someone explain to me how exactly ATP changes the shape of a transport protein? If ATP, when hydrolyzed, releases free energy, how does this energy change the conformation of the structure of the protein? Additionally, why must a phosphate group attach itself to it? Thanks!

So I have NO IDEA how to do this problem. I am assuming it has to do with linear transport because that's the next section in the book but we have yet to talk about this in lab and briefly (one slide) discussed this in lecture. I tried reading in my book which was did no good as it just showed...

Hello! In my course on physical transport processes time and again these type of equations, containing partial derivatives, appear: But how do you actually calculate such an equation? I know how to take the partial derivative from a function like x²tz³. Would it be that I am given a...

Hello there! I'm new on the forum and english is not my first language. I'm working on an art project and I wonder if there's any mean by which I can transport the light from an illuminated scene across a small tube (let say not larger than 5 cm in diameter) and over some distance (let say 2...

In superluminal light pulse experiments, as shown in Fig. 4 of the Letter [Nature 406 (2000) 277], the whole pulse intensity profile observed is advanced by 62 ns nearly without any distortions, and the light pulse energy must be transported faster than the speed of light in vacuum...

Hello! (Wave)Suppose that we have $M$ production stations $A_1, \dots, A_M$ of a product and $N$ destination stations $B_1, \dots, B_N$ of the product. We suppose that $x_{ij}$ units of the product are transferred from $A_i$ to $B_j$ where $i=1, \dots, M, j=1, \dots, N$. The cost of...

I cannot find a website that answers this question, and all diagrams I see do not show that ATP is used. Does this mean that these processes are intrinsically spontaneous? I can see how the electron transport chain is spontaneous, as the oxidation of oxygen to water is favorable (E 1/2=0.7V).

Homework Statement A charge Q = -820 nC is uniformly distributed on a ring of 2.4 m radius. A point charge q = +530 nC is fixed at the center of the ring. Points A and B are located on the axis of the ring, as shown in the figure. What is the minimum work that an external force must do to...

hello all, I just wanted to check my worded interpretation of this otherwise messy result is ok:

Does plasma transport oxygen?

Hello, I've just read and I think I have understood the following result : If we were to geodesically transport all points of a small 2D surface, so small that it would be flat for all purposes, in a direction vertically above it, and if this surface belongs in an arbitrary 3D manifold, then in...

I was reading through a paper about the first case of experimentally proving that electron transfer can occur over the length of a bacterial nanowire. The paper mentioned that, previously, electron transfer was only measured across the thickness of the wire. "Thus far, there has been no...

Greetings PFers, Would it be possible to move microscopic particles of a wide range of composition (conductivity, density, etc...) using a directed beam technology? The idea is to have a fast 3D printing technology (practically no moving parts) that is capable of depositing of a wide array of...

Hello! (Wave) General solution of Transport equation (homogeneous): Method of Characteristics $$u_t+cu_x=0 (\star)$$ We know that if $f: \mathbb{R} \to \mathbb{R}$ is differentiable then $u(x,t)=f(x-ct)$ is a solution of $(\star)$. We will show that each solution of $(\star)$ is of the form...

Hello! (Wave) Definition A partial differential equation is called dispersion equation if it allows solutions in the form of a wave function and furthermore solutions in the form of a wave function with different wavenumbers have different velocities. The relation between the cyclic frequency...

Greetings, PF! I have some questions regarding the problem I attached below. It is some sort of Couette flow variation. It's not homework, I'm just learning the basics of TP on my own. I fully solved the problem with the Navier-Stokes and continuity equations, using some assumptions in order to...

So I've found several instances in which Bernoulli and Conservation of momentum (in Reynolds transport theorem form) give different answers for the study of an inviscid fluid. Let's consider a simple situation as described in my diagram attached. Basically a tap/faucet is releasing fluid, which...

I would like to reproduce results from a much older code to test a new one. I only have the old code's results in the form of plots, not data, but I need data. The older code solves the unsteady vorticity transport equation in 2D with a constant kinematic viscosity term. I'm interested in 2-D...

I'm currently teaching a gen ed course called Relativity for Poets. This is the first semester I've taught it, and it's been a ton of fun so far. If anyone is curious, http://www.lightandmatter.com/area3phys120.html is the class's web page with links to the syllabus and lecture notes. The...