Stream Definition and 174 Threads

Homework Statement Consider a velocity field where the radial and tangenetial components of velocity are V_r=0 and V_theta=cr, respectively, where c is a constant. Obtain the equations of the streamlines. Homework Equations x=rcos(theta) y=rsin(theta) The Attempt at a Solution I...

Homework Statement Given the following stream function: ψ=C(sin(theta)/r) Find the radial and tangential velocity components. Homework Equations ? Don't know any The Attempt at a Solution Absolutely no idea how to even begin. Do I take the integral or something? Any help...

Hey out there in physics land. Okay So I have this one problem. It's about some AIR moving toward a wall A: mdot is 200 m/s T is 25 c P is 100 kpa There is a stagnation point B...where the velocity goes to zero. It's adiabatic and reversible. I am supposed to find Tsub B P subB and the...

As we learned in fluid mechanics, we can devise stream function psi when the flow is 2-D, incompressible. However, I cannot clearly explain why psi can be defined only for 2-D, mathematically or logically. Is there any way to explain this, more than just say that 'just as it is'?

So the other day I was thinking about this problem that arose when I was watching water spiral down a bowl shaped drain. If you can imagine a spherical shell and on the inside there is a fluid stream that is tangent to the interior curvature of the wall. The entrance of the fluid stream is at...

I want to make an RC car that I can control in two ways. One would be over local wifi and I am actually watching the car and controlling it with my iPhone using touchOSC. The Arduino is using the http://asynclabs.com/" to connect to the wireless network at home or Ad-Hoc when no network is...

Hi everybody, I have been looking for a way to calculate the stream function if I know the velocity \vec{v}=(vx,vy,0) of a bidimentional flux. From the formula given for \vec{v}, I know it is an incompressible fluid.

Hi Folks, I think this is the best place to post this, as I see a couple of other fluid questions in here. For some reason, everyone always defines stream function as only applying to 2D flow. The total flow is represented by \vec{U}, where \vec{U} is a 3 dimensional vector with components...

Hi all, I am working on designing a simple turbine for my senior design project. What I am trying to figure out is what the available power in a fluid stream is. I am thinking of the kinetic energy equation but instead of a given mass, I have mass flow rate, which gives units of Watts. Power...

A woman who can row a boat at 6.5 km/h in still water faces a long, straight river with a width of 6.1 km and a current of 3.4 km/h. Let point directly across the river and point directly downstream. (a) If she rows in a straight line to a point directly opposite her starting position, at...

In the classic experiment, light impinges on half-silvered mirror, the mirror reflects just half the light and transmits the rest. The photon before encounter with the mirror is [A>, then afterwards it evolves according to U to become [B> + i[C> (where C is the reflected light). The...

Homework Statement A firefighter, 44.0 m away from a burning building, directs a stream of water from a ground level fire hose at an angle of 31.2° above the horizontal. If the speed of the stream as it leaves the hose is 40.0 m/s, at what height will the stream of water strike the building...

Homework Statement The stream function of a 2D incompressible flow is given by: \Psi=(\Gamma/2pi)*ln(r) Show that the circulation about a closed path about the origin is \Gamma and is independent of r. Homework Equations \Gamma=-\ointV dot ds The Attempt at a Solution So far I know that...

Homework Statement if a point charge is brought near a narrow stream of water will the water be attracted to the charge, repelled from it, or neither? why? water molecules are permanent electric dipoles. Homework Equations not sure The Attempt at a Solution i don't think the water...

Hello there, I have a question, I wonder if you can help me. Homework Statement I am using scales to measure the volume of liquid coming from a bottle, and then differentiating this volume to give flow rate. The bottle emits a constant flow rate and I hold it so that the stream falls...

Plotting Stream lines! (Fluid Mechanics) Homework Statement In this project you are required to investigate two types of potential flow solution: a. Flow over a vertical plate (flow is perpendicular to the plate i.e.  = 90) b. Flow over an inclined plate ( = 135). You are...

Hi, what is the subtropical jet stream? thanks :)

Homework Statement Consider a source/sink in the origin of a coordinate system with a strength equal to 2m and two sources/sinks, each with a strength of −m, i.e. with a opposite sign with respect to the source/sink in the origin. The two sources/sinks are positioned along the x-axis at x = δx...

I was just wondering, is there any equation which predicts when does a stream of liquid( e.g water, ethanol) break into droplets? i think it relates to the speed and diameter of the stream, probably also with diameter, but i cannot find any equations which governs the rule

In Batchelor's text (2000) on page 76, the stream function is defined as \psi - \psi_0 = \int\left(u dy - v dx\right) where \psi_0 is a constant Now I begin with a simple function for u where u = x^3 From mass conservation, \frac{\partial u}{\partial x} +...

I want to measure certain gases in a nitrogen stream, but I have to dilute with nitrogen flow, which is flowed at a much higher rate for a photo-ionizing detector. However, I am getting backflow into the low flow stream. I tried adding a various mixing chambers of increasing size as the PID...

hi.. i need to ask something related to c programming.. (and i don't know if this is the right place to put up this question.. so please redirect me if necessary!) i've read that using fflush(stdin) in C (to flush the input stream) is not a defined way to use fflush.. but, i continue to see...

Okay so I just got my new geiger counter from ebay and was taking apart an old smoke alarm to get the americium out to test it with. I was cutting away the metal housing when all of a sudden their was a snap, the cutters had bent the metal around and it had cut me. I am very scared now that the...

Hi, First of all, Happy new year to you all, I hope you enjoyed it as much as I did :), but its back to work for me now :(. I am an electronics Student and doing a project about control systems to control a vertical jet stream of air coming out of a pipe. My basic setup is a motor that...

What is the difference between the stream function and the equation of the streamlines(if any)? cheers

If if the stream hits the surface at a sharp angle, it splits in two directions. Why is that?

On 14 November we got news ( https://www.physicsforums.com/showthread.php?p=2441424#post2441424 ) that an International Center for Quantum Gravity was being created at Erlangen. This will be directed by Thomas Thiemann, who has a joint appointment at AEI Potsdam, the other main place for QG...

Given the mass flow, Cp, temp of the inlet streams of both hot and cold streams. As well as being given the inner pipe diametre of the double pipe heat exchanger. Also knowing the setting is at counterflow and that the overall heat transfer coefficient and that the temp difference between the...

What kind of subatomic particle streams are scientists able to generate and how do they do it? I know that LHC is banging together proton-protons streams and protons are large bulky particles and interested in finer grained particles. I am like asking if they can emit quark, gluon, boson...

Homework Statement The figure below shows a stream of water in a steady flow from a kitchen faucet. At the faucet the diameter of the stream is 1.20 cm. The stream fills a 125 cm3 container in 18.2 s. Find the diameter of the stream 13.0 cm below the opening of the faucet. (The answer should...

Homework Statement A. Explain why a stream of water coming out of a faucet gradually grows more and more narrow as you descend in height. B. At a certain height below the faucet, the area of the slice of water is A0 and its speed of descent is V0. Calculate the area of the slice of water...

Homework Statement Hi all, I'll outline the situation first, then I'll ask about what I need. Tank (designed by me / other students) which has no closed in top or bottom. Can be any shape, i.e. cylinder / cone / square etc etc. Made from cardboard with plastic bag in the middle acting...

Homework Statement A thin square tungsten foil, 10mm x 10mm, is supported in the centre of a vacuum chamber by thin wires which have negligible thermal conductance. A cooled shield surrounds the foil such that its initial temperature is -37 C. Two parallel slits, 1\mum wide and 1mm long...

Edit: Egad! I misspelled the title, fitting. . . uh, make that "Stream" of consciousness. Not to be a bore. . . I have, of late, become rather obsessed with the science(s). (I guess it depends on one's epistemic commitments as to it being physics or a subset, or individual hard sciences.) It...

Homework Statement A velocity field is given by v = ui + vj where: u = cos(x)sin(y) v = -sin(x)cos(y) x = y = [-pi/2,pi/2] the stream function psi is: psi = cos(x)cos(y) Matlab function: -------------------------------------- function[X,Y,psi] = streamfun(n) if nargin < 1...

Homework Statement I'm trying to work out a theoretical problem, and I don't know how to approach it. Suppose I have a charged gas that is traveling near the surface of a magnetically-responsive solid. I would expect the charged gas to be generating a magnetic field. I would also expect...

Homework Statement A dog wishes to swim across a slow-moving stream. The dog can swim at 2 m/s in calm water. The current velocity is 3 m/s. The distance directly across the stream is 50 m. If the dog points himself directly across the stream how long will it take to get across the...

Homework Statement i want to use finite difference methodolgyto determine the steady-state potential flow field in a two dimensional duct using a square mesh and get epsi at every grid node and graph the stream lines...any suggestions ? Homework Equations i've got an equation epsi(i,j)...

hi, I had a question regarding the rc4 stream cipher. I understand it is a bunch of permutations to the initial Array that goes from 0 to 255 with respect to the key. However is there such a key such that after the permutation S is still the same? (ie still goes from 0 to 255)? Any help...

why don't they say "stream of particles" prepare yourself for an incredibly stupid question. i don't even know if I am posting this right. if I am intruding on a discussion please excuse me. i just now registered because this question was bugging me. i doubt ill stop back to this forum so if...

Homework Statement A continuous stream of water is flowing out of a faucet and falling into a sink below. Explain why this stream of water is narrower at the bottom (near the sink) than at the top (near the faucet). Hint: Think about the change in velocity and the change in pressure as the...

hello folks can somebody open these streams? http://web.mit.edu/fluids/www/Shapiro/ncfmf.html" I use Media Player Classic with real alternative and other k-Lite codecs, never had problems with the player at all but these bastards just won't play?! any suggestions? (I don't want to use...

Several questions they may not be all answerable but hey :D How do proton and neutrons stay together? If one's got a positive charge and one's got a neutral charge there's nothing holding them together? Once a proton is split from a neutron and/or it's nucleus would you be able to bind them...

Homework Statement Given a set of points in 3d space (x,y,z) each having a velocity vector (u,v,w), create a general algorithm for tracing out a stream line. The points are locked to a grid, so data points are evenly along an axis. (ie, increment along x only and it's always the same change...

Homework Statement A watercraft is crossing the stream to reach the pier. (See attached figure.) Basically, I have to derive an ordinary differential equation of the path the watercraft travels, which I can then solve using MatLab, etc. i.e. derive \frac{dy}{dx} in terms of V_{W}, V_{B}...

Hi, I'm looking at finding a way to determine when a stream of water of a certian diameter coming from a hole at a certian pressure will break apart due to gravity and surface tension into descrete droplets. Bernoulli's principle can give me the diameter of the stream at various times but...

Homework Statement In addition to the customary horizontal velocity components of the air in the atmosphere, there often are vertical air currents cuased by buoyant effects due to uneven heating of the air. Problem: Assume that the velocity field in a certain region is approximated by...

I've been having difficulty with this problem and can't seem to find where to start. Any help would really be appreciated. A water insect maintains an average position on the surface of a stream by darting upstream (against the current) then drifting downstream (with the current) to its...

Homework Statement A jetliner can fly 7.35 hours on a full load of fuel. Without any wind it flies at a speed of 3.42 x 10^2 m/s. The plane is to make a round-trip by heading due west for a certain distance, turning around, and then heading due east for the return trip. During the entire...

How many people out of the original number entering as a physics or physics/math undergrad (overall, not at any specific university) will: 1. Get their B.Sc.? 2. Get their Ph.D.? 3. Become a PostDoc, or stay in the academic stream in some way? 4. Become a professor? 5. Become a tenure...