Flow Definition and 1000 Threads

Referring to the problem in the attachment, the author mentions that if we consider the coordinate system attached to the bicycle and the bicycle accelerates or decelerates, the flow past the bicycle becomes unsteady. For an unsteady flow, we know that nothing changes at a given location on a...

Hey! :o The velocity field $u=ax^2, v=bxy$ ($a, b=\text{ constant }$) represents a flow field of an incompressible fluid. Construct the streamlines and find the cutoff points of the flow ($\overrightarrow{u}=(u,v)=0$). From the fact the fluid is incompressible we have that $$div u=0...

I know this is easy but i need to know the flow velocity through a pipe reducing in diameter inside a canal. the water velocity is 3m/s water depth is 1.5 m the pipe is at the bottom inlet diameter 0.9m small reduced diameter 0.6m outlet diameter = 0.8m note: this is an open canal with...

Hey! :o In my notes there is the following example: One dimensional incompressible flow in a channel of constant section. $$\overline{u}=(u(x, t), 0) \ \ \ \ \ p(x, y, t)=p(x)$$ incompressible flow: $\partial_x u=0$ Euler equations: $\rho_0 \partial_t u=-\partial_x p$ $$\Rightarrow...

Assuming a flow can be idealised as incompressible, then can you use the constant pressure assumption ? I just want to get my understanding clear. My problem is the following.Consider a fluid element with volume ##V## and a fixed number of molecules. If the flow is incompressible, then the...

When current flows in a conductor, is it evenly spread out in the conductor? Not flowing(concentrated) in a certain part? And if we split the conductor into smaller pieces(visually not physically) the current divides out evenly so that when all those split pieces add up it equals the same as the...

I have a 4inch pipe and I know the pressure at the start of the pipe is 4 bar. How do you calculate the flow rate?

I posted this on Eng-tips and no replies yet:( I'm trying to design an as-simple-and-cheap-as-possible supersonic wind tunnel using an air compressor (this even possible? given the energy losses from shock waves...). I have access to a Porter-Cable 150psi, .8hp air compressor. Questions: 1...

So, there's a project I'm working on (no, it's not school related), where I'm trying to figure out how to measure thermal conductivity of a material using laminar flow. The idea is to integrate this into a larger system, and it's a measurement I'd like to take in the process. I know the...

It is my general understanding that according to KCL, current requires a closed loop to flow in DC. However, this is apparently not true in AC; current doesn't needa closed loop to flow. I have drawn a circuit below which causes confusion: C1 is a charge capacitor, R1 is a resistor, I1 an...

If drift velocity of electrons changes in AC, how does electricity flow through a circuit to then lose potential energy to the devices in the circuit? Also considering the change in direction, does that mean that the live wire and neutral wire also switch roles in AC mains? I am very confused...

I have this problem and have been pulling what's left of my hair out: The Wivenhoe hydroelectric power station requires water to be pumped from Wivenhoe Dam to Splityard Creek Dam, using two pumps (each consuming 250 MW of power at 98% efficiency) to elevate the water approximately 70 m. At...

As part of a research project, I've been asked to design an industrial scale model for the synthesis of titania nanowires. These are currently being produced at a scale of 500 g every three days (being that it takes three days for the nanowires to morph using the given method). My director has...

I'm working in an engineering internship after my first year and we haven't covered fluid dynamics in my program yet. I've been assigned to find flow rates and velocities in several branches of a suction (dust collection) system in our factory. The main branch has a diameter of 30" and is...

I'm not learning physics in English, so terminolgy might be wrong. 1. Homework Statement How does this circuit function? Where do the electricty flow? Homework Equations No equations The Attempt at a Solution Not sure what to put here? My question is basically how it work. As far as I know...

I have a condenser with a mass flow rate of 60kg/s, an initial point 1: P=50kPa, Quality = 95% and a final point 2: P = 50kPa that is saturated liquid. cooling water flows through the condenser with a mass flow rate of m(dot) and has a delta temperature of 15 degrees Celsius. how do i...

Let's say i have an air pump which produce plenty of air flow, but almost no pressure. Is there a simple way to turn this high flow, low pressure into high pressure, low flow? I'm thinking something akin to a gearbox turning fast spin, low torque of a motor into a high torque, slow spin output...

Hello I am trying to design a vacuum using venturi. I cannot quite get the air flow created by the rotation of the fan, which is connected to the engine. How is the relation between the fan speed and the flow rate created by it? I know the proportionalities between the speed, power and the...

Hello, I'm having a hard time coming up with a flow velocity out of a nozzle. I have a fan that is putting 300 cfm of air through a 3" ID hose. The 3" hose is 45in long, and ends with a rectangular nozzle that has an opening 4.5" x 0.5". Any help would be greatly appreciated.

Homework Statement Use the incompressible version of Bernoulli’s equation to estimate the flow-velocity when water from the top of a reservoir, 100 m above the river, reaches the river via a pipe. (neglect the atmospheric pressure change, and assume the water is flowing into the river at...

hello In venturi meters, orifice plate meters and generally when there is a neck, constriction at a point in a pipe there is, at that point, a drop in pressure and an increase in velocity, so that the whole energy is preserved (theoretically) my question is, why if we increase the flow rate...

I am in need of a formula to calculate mass flow rate of liquids through a known orifice size and known pressure/secondary pressure. I need to do this for multiple liquids and I know the specific gravity for each liquid. can anyone help with this formula.

I am currently trying to use a centrifugal fan to force air through a small tube however i am looking for some information on how to better the design and performance as what i have currently is severely lack-lustre. This is just a prototype for controlling rate of airflow and all i had on...

I would like to setup a subsurface irrigation system for my garden. I have several beds which, while I made each one perfectly level, are at different elevations (about 1 or 2 feet between each) . The source of the water will be a permanently mounted bucket, barrel or cistern of some kind...

Hi guys, I have a question to you that has been bothering me for a while now. It is about adiabatic flow in a duct or more specifically in the air intake of a jet engine. In lectures and textbooks it is always stated that the total temperature in an adiabatic flow does not change. Hence the...

Homework Statement A hose with a nozzle 80 mm in diameter ejects a horizontal stream of water at a reate of 0.044 m3 s-1. With what velocity will the water leave the nozzle? What will be the force exerted on a vertical wall situated close to the nozzle and at right-angles to the stream of...

Hello, I am trying to design a hydro penumatic circuit. I have shop air at 80 Psi. I need hydraulic pressure of 160 PSI. So I am using pressure booster/Intensifier to pressurise it. there will be air on one side of intensifier and oil on other side of it. my question is if I block path of oil...

When answering a related question on physics forum, I found something I seemed to be confused about: Suppose we have a battery connected in series to a capacitor with no charge. A capacitor with no charge on it acts like an open circuit. I know what happens next: the battery charges the...

Homework Statement Find the velocity field u(x,t) Homework Equations \rho = constant u(0,t)=0 u(0,L)=0 \frac{\partial u}{\partial t} = \nu \frac{\partial ^{2}u}{\partial x^{2}} u(x,0)=U_{o}[sin(\frac{3\pi x}{L})+0.7sin(\frac{9\pi x}{L})] The Attempt at a Solution I have absolutely no idea...

hi all i want to simulate rarefied flow in a microchannel i want to apply the heat flux condition on the external slip wall but the external slip wall have a temeprture contition (Tw)! how can i define heat flux condition on the external slip wall? and how can i find or define nusselt number in...

I've Attached the question and my answer to question 1 to task 3 and guidance if I've done it right? Or any guidance?

Homework Statement A variable , opposite external potential ## E_{ext} ## is applied to the cell Zn | Zn2+ (1M) || Cu2+ (1M) | Cu, of potential 1.1V . When Eext < 1.1 V and Eext > 1.1V , respectively electrons flow from : 1. anode to cathode and cathode to anode 2. cathode to anode and anode to...

I am designing a system for an engineering project at school. It's essentially a clock to be powered by water turning a mechanical system of gears (not generating electricity). Imagine a rectangular basin full of water placed at some height above the ground. There is a hole in the bottom...

This is a puzzle I came up with. I'm trying to judge whether the solution is obvious or not. Technically it's more closely related to quantum computation than quantum physics, but... let's try it anyways. We find ourselves with the following network: The goal is to find a way for the sender...

Why can't I find any LED's at 488nm? I am trying to find a cheaper light source than the traditional argon ion laser for a possible fluorescence activated cell sorter. See link below for schematic. Does anybody know a good retail site for lights in this spectrum I can't find good results with...

Homework Statement The initial separation of the pistons is 2cm. They are submerged in water at room temperature. I need to calculate the work required to have two pistons touch, find the volumetric flux of the water as a function of time, and the force at a given time Homework Equations...

Homework Statement [/B] Problem: In order to simplify your analysis, you will assume alcohol has the same properties of water so you can use the steam tables. You load the 30 gallon still 1/3 full with nearby water at 1 bar and 20°C and mash(assume the mash has negligible influence on...

Hi everyone, I've got a newbie question which is probably more complex than I imagine so please bare with me. As a small DIY project I've trying to build a small exhaust filter system (A) for another device that produces undesirable fumes (B). I'm trying to work out if an axial fan (generates...

I have been asked to solve the actual load flow distribution in a given power network using two iterative methods. I have chosen Jacobi and Gauss Seidel. we have to use MATLAB to find where the solution converges. I am fine with all of this, but we have been tasked with providing graphical...

Homework Statement A sphere is moving in water at a depth where the absolute pressure is 124kPa. The maximum velocity on a sphere occurs from the forward stagnation point and is 1.5 times the free stream velocity. Calculate the speed of the sphere at which cavitation will occur. Can anyone...

Homework Statement Let a spherical object move through a fluid in R3. For slow velocities, assume Stokes’ equations apply. Take the point of view that the object is stationary and the fluid streams by. The setup for the boundary value problem is as follows: given U = (U, 0, 0), U constant, find...

There is a pipe which is bent in the shape of a right angle as shown. The cross section area of the pipe is A, the velocity of the water inside is v, and the density of water is ρ. The momentum flowing per second towards the right corner is thus: Av2ρ towards right and momentum flowing per...

Homework Statement Following the amount of C1 front, the output Z be 1 . Following an amount of C2 front, the output Z must be 0 . Otherwise, the output remains unchanged. Homework EquationsThe Attempt at a Solution in Attached file. This is the answer but I really do not understand the...

Homework Statement You open the plastic bottle lid to take a drink,and notice fluid flowing from a small hole in the bottom of the bottle. You put the lid back on and the flow stops. Explain why the flow did not start until the lid was off. Explain why the flow stopped when the lid was put...

Please could someone verify this statement as I understand things: If an object has a low reynolds number (or the fluid is very viscous) then it is dominated by viscous forces and inertia plays no role. The object is in a laminar flow regime. That last part, is it correct? What I'm asking is...

Homework Statement Q.2 One type of bearing that can be used to support very large structures is shown below. Here fluid under pressure is forced from the bearing midpoint (A) to the exterior zone B. thus a pressure distribution occurs as shown. For this bearing which is 30cm wide, what...

Hello everyone! I am new here. I have used this forum on and off through google searches in the past and learned a fair bit from the posts. This is the first time asking anything. The question is probably extremely simple but has been overrun in my head for a week! It is in regards to...

Hi, For my experiment I was asked to determine the length of the tube for a fully developed flow to occur ( Entrance length as shown in the attachment) , with the following flow parameters. Flow rate : 1, 5, 15 lit/min Fluid: Water Tube Id: 1 inch. My question How do I find out the length of the...

Look, I found that there exist two kind of electric current: conventional flow and electron flow. I have read that in every situation I have to use the conventional flow, however I'm going to work with electric circuits using copper wires. In solids, only negatively charged particles (electrons)...

Homework Statement Homework Equations ρ=789, μ=.0012 The Attempt at a Solution From the energy equation we get hf=0.9 We know that hf=f(L/D)(V^2)/(2g) [sorry don't know how to use latex after they removed the bar on the right] Now I can substitute V for Q, but I'm stuck with f and Q as...