Flow Definition and 1000 Threads

Given a wing that lifts a plane moving through it at velocity V, how do I figure the minimum volume of air flow necessary to lift the same wing if the plane is still and the air is blown over it? Would moving that volume of air over the wing artificially require more power than what is required...

Have been referring to this forum a lot and I think I finally understand it. However I couldn't find a discussion specific to applying the Laws of Ohm, Poiseuille and Bernoulli's to why we use a pressure wire to study coronary blood flow through a lesion site in the coronary artery. So I made...

Consider the following flow: x = (1+ct)x0. Let the density rho(t) = rho0/(1+ct) so that the flow conserves mass. Physically, this is just a bunch of fluid elements on the positive x0-axis each given initial velocities that are proportional to their initial positions. Each fluid element should...

Hey, I'm a student who has to complete a written assignment for physics. I chose to launch water rockets and investigate the effect of volume on the range. I am trying to also come up with a mathematical model however I am struggling to understand an equation I found the following equation to...

How to calculate the speed of cross flow water turbine? Help, I'm struggling on our machine design.

I am currently modeling the altitude that a water rocket can attain. In order to do this i am first modeling the the thrust phase. Due to the water mass decreasing with time (the same goes for the pressure - it decreases over time as the water is expelled out of the nozzle). This is an...

Hi, Could someone please help me in understanding how the air is thrust rearward by a propeller? I am specifically interested in how an axial-flow compressor, which uses aerofoil shaped blades to force the air through the engine does so, however I feel a good start is a propeller. It makes...

Recently looked at why temperature flows from high Temperatures to Low temperatures.Essentially it was laid on two Fundamental Assumptions: 1.Energy is conserved in the isolated system 2.Entropy in isolated non quasi static systems will always tend to increase. Lets take a brief look at...

Hi there, Hopefully this is a very easy question and you all can just confirm this for me. When calculating heat transfer into a fluid from a heated tube, is it correct to say that the heat transfer coefficient is *not* dependent on the tube diameter? So, if we solve for T_{out}, we get...

Lets say I have two spheres of equal dimensions, one charged and one uncharged. Now I connect them with a conducting wire. They will now very quickly reach equal potential. Can it be said that the total charge on each sphere remains almost unchanged?

Homework Statement Shown in the figure attached. Circular duct with a diameter of 150 mm, strikes a cup and exits through a circumferential slot to the atmosphere. Mean velocity in the duct = 100 ms^-1 Air density = 1.1 kg/m^3 Dynamic viscosity of air = 19.05 x 10^-6 kgm^-1s^-1 (a) Determine...

when in LC oscillation current flow from inductance to capacitor and charge is opposite polarity. why don't current flow in reverse of it and charging the capacitor in same manner as it was earlier.

I'm trying to understand calculation made Robert Zubrin in his presentation on Dipole Drive source: In here he made the following statement "A Coulomb of protons has a mass of 0.011 milligrams. If the jet power is 400 W, and the potential difference is 64 V, so the proton current will be...

Hello, I'm a chemist and I'm currently working on my PhD on materials science. I'm trying to determine the pressure difference necessary to achieve the desired gas flow inside a chamber. The scheme of the chamber is the following: I have a big chamber which is evacuated to 0.2 bar, and another...

In both the cases, the flow cross section area of the pipe is reduced.But in case of nozzles the velocity increases,pressure reduces and the flow rate is maintained.But in case of flow control valve, flow rate changes.(Assuming the fluid to be incompressible) Why is there a difference between...

Hello everybody, I hope you are doing fine. I'm currently designing an injector for a hydrogen peroxide - ethanol engine, and the following formula is confusing me: Q = Cd * A * sqrt( 2 * dP / rho); where Cd is the discharge coefficient, A the total area, dP the pressure drop, and rho the...

Hello everybody, This is my first post. I've been working on a liquid rocket engine for a while, but I have never gotten to work on its feed system (fluid mechanics), until recently. We are using a very simple pressure fed system, and its main goal is to deliver the propellants at a specific...

Hello everyone.. I am using 2-dimension Navier Stokes equation, but I confused that my problem is compressible or incompressible flow form, because if I have initial pressure and temperature and velocity for x-axis only in one grid that they are so very high but the others grid are zero. Can I...

I recently read in a Khan Academy article that the rate of energy exchange through heat across a material of thickness ##d##, surface area ##A##, and thermal conductivity ##k## can be approximated by $$\dot{Q} = \frac{kA\Delta T}{d}$$ where ##\dot{Q}## is the heat rate and ##\Delta T## the...

Hi. Just looking for an average answer to a practical scenario. At work we use a liquid O2 cylinder which includes an outer jacket that houses a regulated gas pressure of 24 bar. I need to calculate the flow rate in l/min when the supply tap (15mm diameter) is open fully? This is essentially...

As per work energy principle, the energy spent in moving an object is stored as kinetic energy.Flow work is done to make the fluid move.Why is it not included in kinetic energy (i.e) why kinetic energy and flow work are considered seperately?

Could someone please go here... https://en.wikipedia.org/wiki/Flow_separation And explain to me the difference between Flow and Boundary Separation discussed in the opening. Because this explanation makes no sense to me. I have the problem. I just don't understand the difference.

Is it true that the laminar to turbulent flow transition has been finally solved? From what I've read, it seems to be well described by the Directed Percolation Model. I can hardly believe it since I haven't seen the news in the press (from my point of view, it's a long standing unsolved issue...

Homework Statement 12kg of a fluid per minute goes through a reversible steady flow process. The properties of fluid at the inlet are p1 = 1.4bar, ρ1 = 25kg/m3, C1= 120m/s and u1= 920kJ/kg and at the exit are p2= 5.6bar, ρ 2= 5 kg/m3, C2= 180m/s and u2 Homework Equations u1 + P1V1 + (C1)2/2 +...

In case of isobaric expansion, the system expands at constant pressure(the external pressure i.e. the resistance is constant.).In case of flow work, the fluid trying to exit the control volume, pushes against the pressure at the exit of the control volume or when entering the control volume, the...

Homework Statement Produce an detailed understandsing of the anatomy and function of the lymphatic system, using correct scientific terminology to explain the rationale for use of corrective treatment for lymphedema. Homework Equations N/A The Attempt at a Solution Lymphatic edema is the...

I have been asked to find a machinable plastic (or dielectric) that will be subject to continuous loading (20 years) that will be subject to stress of appx 100 KPa at a max temp of 64C. While not a high speed or high energy situation, it is a rotating, close clearance application and the...

Hi. I'm a mechanical engineer, but working as Safety Engineer. I have a question how to calculate the flow rate of hydrogen gas before a flow controller in case of leak through a 4.5 mm line at 35 bar pressure. Thanks in advance.

I having difficulty wrapping my head around a concept that I wish to solve. I have a 10L tank of compressed air at 100psi. When an outlet hole of cross-sectional area of 0.115 in^2 is opened, I wish to develop a curve of pressure vs. time from t=0 until pressure drops to atmospheric. Many things...

Hi ! I need help on the following problem : I've got a liquid in a pipe that splits into 2 in a "T-junction" (see drawing below) : I want to know if the liquid will split equitably (50% to the left and 50% to the right) or not. Length after the elbow = 3m Inner Diameter 0,27 m Flow volume...

Complete question: Will flow ever reverse or stop if we increase resistance in this pipe scenario? There are 2 comunicating vessels. The highest vessel is coninuosly alimented with new water. Water in excess flows down on the sides. Water will try to reach the same height in both vessels, so...

The kinetic energy of electrons in a conductor is roughly 9 orders of magnitude greater than the kinetic energy from the drift velocity of the electrons. It seems that the kinetic energy from the drift velocity is not enough to account for the heating, where does the heat energy come from? Cheers

Homework Statement A 5m long heated pipe is used heat up water from 15°C to 65°C. Water flow through the pipe is 10liter/min. The heating gives a constant heat flow in all parts of the pipes surface. The inner and outer diameter of the pipe is 30 and 50 mm, respectively. Calculate the heat...

Homework Statement If you have a pipe where an incompressible fluid flows. What happens if we get cavitation - can we still say that the volumetric flow rate is "conserved" in the pipe?

Hello, I have a simple question regarding current flow through a common part of a circuit. I encountered this as I am reading "Code: The Hidden Langauge of Computer Hardware and Software" by Charles Petzold. The images I've attached display what I'm talking about. I'd like to know if there's a...

Homework Statement [/B] We have water flowing in an open channel. A small tube is placed in the channel, and the water raises to a height "l" above the water surface. The distance from the water surface to point 1/2 (points are at same height) is d. At point 1 the fluid velocity is V1 and at...

Homework Statement One end of a solid cylindrical copper rod 0.200 m long and 0.0250 m in radius is inserted into a large block of solid hydrogen at its melting temperature, 13.84 K. The other end is blackened and exposed to thermal radiation from surrounding walls at 500.0 K. (Some telescopes...

I'm working with tap water. I'm building a fertilizer injection system, and need to control the rate that water flows through the bypass, through the fert tank, and back into the main line. At small flow values, reynolds numbers are on the non-flat part of the curve, so making something that...

Hello all, I've come in search of some information, and hopefully if possible a little bit of help. On searching the web for various ways to improve my truck in general I came across this very interesting mod that I've never once heard of in my entire life, "The Gadgetman Groove", which is a...

Hi. I have been trying to solve this problem that has been keeping me up at night for a coupe weeks at least. If anyone can help me, I would be greatly appreciated. Hot air enters a cylindrical duct. The duct has some R-value and radiation and convection is being accounted for on the outside...

I recently re-read an article by Muller (https://arxiv.org/pdf/1606.07975.pdf) about the flow of time, and the possibility of time reversal given sufficient energy dissipation (basically during black hole evaporation, he concludes). Although the paper is on arXiv and not peer reviewed, Muller...

Using a pump we are cycling water through a capsule with filter media inside; while measuring the flow rate (l/min) and the pressure (psi) going in and the pressure going out. The water is cycled back into the same storage tank. As the flow rate increases the differential pressure should change...

Hi, I have a question about air flow. My room is located on the corner-end of my building, on the 7th floor. I have two windows, each one facing a different side of the building, and one of the windows typically produces the breeze, and the other never does. When the door to my room is closed...

Hello PF, I am new to the science of turbulence and fluids but recently I have been working with my professor on 2D steady state turbulence and I was looking for a way to model and simulate this scenario: I have a flow affected by a spatially varying magnetic field and having a current pass by...

Homework Statement We bind two batteries with voltage 2V and 1.7V with inner resistance 0.2Ω and 0.1Ω in parallel series in such way that we bind each positive poles and negative poles together. What current runs trough the circle? What is the voltage between contact points of the batteries...

Homework Statement I don`t know if the image will show so I`m also adding a link to the image of the problem. This problem is a modification my professor made to the one in the link below(*), he changed the rigid diathermic partition into a movable partition. I`m supposed to find the...

Homework Statement A pump is used to move water through a pipe of diameter 150mm, Figure below. The water has a temperature of 20 Celsius and an absolute pressure of 100KPa. The pump moves the water up a vertical distance of 2m and the water exists at atmospheric pressure. Q1) Assuming the...

I am simulating flow through porous medium with VOF method and species transport. For phase change i have Lee Model, and i have no idea about the evaporation frequency and condensation frequency Second I am using the evaporation frequency as 30. The liquid is n-heptane while for vapour phase i...

Hi there, I am currently looking to build a rotating kiln to provide the necessary heat/res. time/gases to react a solid feedstock. The problem that I can envision, however, is that the solid (which is fed as small particles) may become entrained in the counter-current gas flow inside the...

I'm having a brain storm, If I have an 8 cylinder 4 stroke engine running at 4000 rpm over a 10 minute test and it consumes 4.4 Kg of fuel, then is the fuel mass flow rate as simple as the 4.4 Kg divided by the time to give me an answer on Kg/sec ? Thanks,