Fluid dynamics Definition and 609 Threads

Hey guys! I'm working on a problem for which i somehow just can't figure out what I'm doing wrong. This is the problem: I think I've figured it out, but somehow i think i make an error with the maths. First of let's determine the equation for the temperature (in Kelvin): $$T(z) =...

Homework Statement This is simply a sanity check concerning the system described and attached. My concerns are detailed within my attempts at the solution. Any guidance will be greatly appreciated! The diagram attached represents a process for which a pump and associated pipe work require to...

As the flow rate increases frictional force increases but friction factor(Darcy,Fanning) decreases with Re. Can anyone explain what is the concept behind it?

Hi, PF! Recently, while reading chapter 6 of Incropera's Fundamentals of Heat and Mass Transfer I got into a confusion regarding the velocity boundary layer. The book first states that, as the flow becomes more turbulent, the boundary layer gets thicker, as indicated by both figures attached at...

Hello! I have encountered some trouble with choosing the right reference points when using Bernoulli's equation and I would be glad if you could help me sort it out with this made up example. :) 1. Homework Statement There is a large, open, cylindrical water tank with a cross section area of...

which has different radiuses at both end. Its actually two pipes merging after the entrance going straight and somewhere close to middle of the pipe it's bent 90°. So for simple pipes it's =4*Q π*r^3 But what for the pipe I...

Hi, I'm seeking the formula to calculate how water moves from one tank into another through a perforated plate driven by waterlevel compensation. I found the calculation for the discharge of water through submerged orifices, but I think the calculation does not include that holes, one above the...

This is not homework, but something work-related. However, I will post it here since it's homework-relatable. 1. Homework Statement Known variables: Qin , A (and obviously the diameter D of the pipe as well as g = 9.81 m/s2). The pipe outlet and the top of the tank is at atmospheric...

I work in the mining industry, focused on the development of solutions related to environmental protection. Although my background is in Natural Science and Ecology, I have a passion for physics and engineering! I am always interested in expanding my knowledge and ability to design and...

Homework Statement A time-dependent two-dimensional fluid flow is given, in a Cartesian coordinates system (x, y), by the velocity field: u = (y, t-x) Show that, at time t = 0, the streamlines of this flow are circles centred on the origin. Find equation of the streamline that passes through...

Hello there Physics Forum! This is my first post here. This problem has been boggling me all day and I'm need of help in piecing together what I've come up with so far. I'm currently working on a personal project related to paint spraying. In this project I'm using a syringe & needle to feed...

Hi guys, this is my first time on the forum, and I was wondering if you could help me out with this problem. I have regrettably chosen a topic for a high school lab assignment that was quite complex compared to what was expected. For my investigation, I've drilled holes of varying size into...

I'm not really sure where to post this. I saw that this Homework section exists even for technically non-homework (I'm designing a machine at work, but the problem is homework-esque and my fluid dynamics knowledge is rusty at best). I'm not sure if this introductory or advanced, and the template...

in fluid statics we have learned that p =patm+density*g*h. is the same equation valid in fluid dynamics?

Hi All, I have a situation were I need to evaluate the heat transfer coefficient of a horizontal surface. The surface has tubes within although I first used "flow across a bank of tubes", this has been untrue due to the air flow coming from above the surface flowing vertically (and...

Homework Statement Water is pumped steadily out of a flooded basement at 5.0 m/s through a hose of radius 1.0 cm, passing through a window 3.0 m above the waterline.What is the pump’s power? Homework Equations Volume and mass flow rates are constant R_v = Av; \quad M_v = \rho A v...

When designing the fuel plumbing for an efi system, do pressure drops in the fuel lines need to be considered when there is a pressure regulator? If so why? Been reading up a lot on plumbing design lately about how the goal is to minimize restrictions in the lines which ultimately cause...

Homework Statement Consider the flow of a fluid with viscosity μ through a circular pipe. The velocity profile in the pipe is given as U(r)=Umax(1-rn/Rn), where Umax is the maximum flow velocity which occurs at the center line; r is the radial distance from the centerline; and U(r) is the flow...

I'm trying to understand how the Navier-Stokes equations are derived and having trouble understanding how the strain rates are related to shear stresses in three dimensions, what a lot of texts refer to as the 'Stokes relations'...

Homework Statement A hole is punched in a full milk carton, 10cm below the top. What's the initial velocity of outflow? Homework Equations P2 = P1 + ρgh Conservation of energy of fluids: P2 + 1/2ρv22 + ρgy2 = P1 + 1/2ρv12 + ρgy1 The Attempt at a Solution Set the top of the carton as P1, and...

Hi all, I'm considering an fluids example that's giving me an apparent contradiction when I consider it from the perspective of Bernoulli's Equation vs. the Equation of Continuity. What I'm thinking of is the common observation that putting one's thumb over a garden hose results in an increase...

Homework Statement Basically, the goal of the "project" is to find the equation for oscillation of a "fractionless" fluid in a v-shaped tube, regarding the angle. I know how to solve the same problem regarding a u-shaped tube, but in this case, I can't figure out where to place the angle in the...

Hi, I'm trying to make sense of a wave propagation problem. It's a 1D problem, modelling propagation of density perturbations which travel like waves in a fluid. The problem is governed by the mass and momentum equations and density is related to pressure using the bulk modulus of the fluid...

Homework Statement [/B] Find an equation for the flow velocity of a river that is parallel to the bottom as a function of the perpendicular distance from the surface. Apply the boundary conditions given and solve, and find the velocity at the surface. Note that the coordinates are: x is the...

So you can solve the Stokes equation for flow around a sphere to obtain the pressure in the fluid: p=p0-3nuacosθ/2r2 where n is the viscosity, u is the speed of the fluid (along the z axis) far away from the sphere, a is the radius of the sphere and r,θ are the usual spherical polar coordinates...

Hi All, I'm hoping to work on deriving the governing fluid flow equations for a frisbee in flight theoretically and then to test it on a wind tunnel, and compare results. If u could please help on how do i apply/derive the necessary equations. Respectful Regards

Hi All, I'm hoping to work on deriving the governing fluid flow equations for a frisbee in flight theoretically and then to test it on a wind tunnel, and compare results. If u could please help on how do i apply/derive the necessary equations. Respectful Regards

Homework Statement a Flat rectangular door in a mine is submerged from one side in water. The door dimensions are 2m high, 1m wide and the water level is 1.5m higher than the top of the door. The door has two hinges on the vertical edge, 160mm from each corner and a sliding bolt on the other...

Homework Statement A rectangular vertical plate is submerged in water. The top edge is horizontal and at a depth of 0.6m. The length of the vertical edge is 1.2m. determine at what dept under the water surface a horizontal line can be drawn on the plate such that the hydrostatic forces on...

Homework Statement A tree loses water to the air by the process of transpiration at the rate of 110 g/h. This water is replaced by the upward flow of sap through vessels in the trunk. If the trunk contains 1900 vessels, each 100 μm in diameter, what is the upward speed of the sap in each...

Homework Statement The attempt at a solution Hi all, I am tasked with finding the static thrust generated by this convergent-divergent nozzle. The stagnation pressure is known the inlet. Now, personally, I would've thought drawn a control volume around the entire nozzle. And then said...

Homework Statement [/B] "Derive a relation between the static pressure P at a point and its depth y from the free surface of the liquid. Given the surface density of liquid is ρο, and compressibility of the liquid is k." Homework Equations ##ρ(P) = ρ_οe^{kP}## ##dP = ρg dy## The Attempt at a...

A question was posed to me with the following diagram. http://imgur.com/6ltYKd5 11 Sprinklers, in series with identical heads, but 10 and 11 displaying a much smaller spray pattern. 1. Is this possible, and under what circumstances. 2. What would a good solution be to prevent this? My...

I've come across two different approaches to quantifying what l is in the equation for hydraulic gradient Δh/L. In this first picture L is the parallel distance along the datum across the reference plane But in this second picture L is the length along the pipe Why are the two L's...

I've read that drag coefficient depends on the shape of the object but I am confused as to what shape means. Does it mean geometric shape or is area included in that? Say I have one sphere of radius r and keep fluid velocity, density, and viscosity constant and find its drag coefficient. Would...

< Mentor Note -- please remember to use the Homework Help Template when posting schoolwork questions >[/color] Consider the fully developed laminar flow due to gravity of water in a vertical circular tube. Assume atmospheric pressure at inlet and outlet. Show that the relationship between...

Homework Statement Hi, I wasn't sure whether to post this here or in the engineering forums. Since it's mainly math/theory I figured here would be more appropriate. Feel free to move it if it doesn't belong here. All relevant info etc. is in the picture, thanks. Homework Equations The...

Hello, PF! I have some doubts about setting up shell balances in a cylindrical geometry. Consider a fluid flowing down a vertical pipe. In order to perform the momentum balance, we take a cylindrical (annular) shell of length L and width Δr. The analysis of such system can be found in chapter 2...

I have attached a question about the general constitutive law for Newtonian fluids (it contains a lot of math, which is easier for me to type and send to PDF than put it on here.) Basically, I do not like the einstein notation and I decided to write everything out loud and clear, since my...

I am curious as to whether a nozzle at the end of a pipe that is completely submerged in water and has a pressurized flow being pumped through it in a closed condition can increase the amount of flow and pressure of the water in a pipe fixed to the exit side of that nozzle if the nozzle uses the...

So I was sitting around pondering about forces, and I found myself thinking about shock-waves. Whether they're caused by supersonic travel, or explosions, the pressure at the front of the wave-bow shock pressure is a force. So I started thinking of a way to generate them without having to go...

A hypodermic syringe contains a medicine with the density of water (figure below). The barrel of the syringe has a cross-sectional area of 2.18 10-5 m2. In the absence of a force on the plunger, the pressure everywhere is 1.00 atm. A force of magnitude 1.78 N is exerted on the plunger, making...

(I am new to this forum so please do forgive me if I am posting at a wrong place.) Hello, I am a final year student of BS Mechanical Engineering and method of characteristics is not a part of our curriculum. In-fact I heard of it first time after finally picking my FYP. My final year project is...

Hello all! I am interested in how much energy a HVAC VAV box consumes. Can anyone help me come up with the following equation? I don't need to know the exact formula, and can assume an uncompressible fluid and/or ideal gas. Been about 20 years since I have done this and am a bit rusty...

I have read articles regarding Chinese junks which utilise rudders made of rubber, and they usually have diamond shaped holes in them. These articles claim that the holes provide better handling of the junks compared to a full rudder without holes in them. What are your thoughts regarding how...

Hello everybody, I have a new thread to post,it is very important to find a solution for this : -Imagine a box full of air particles.The particles are forced to move to a point A on the edge of the box.My question is now,how can I mathematicly describe the movement of these particles toward...

Some days ago I got confused trying to solve an exercise about fluid dynamics. Trying to simplify the problem here is a similar situation: I have a cistern connected to a tube containing a fluid as shown in the picture below. Assumming that the fluid is incompressible... I know from the law...

Homework Statement Water is flowing along a pipe. Points B and C in the pipe are at the same height but point A is at a higher elevation.The pipe has the same cross-sectional area at points A and B but is wider at point C. Rank in order from largest to smallest, the pressures at the three...

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...

Homework Statement Does the delay of propagation of pressure gives a torque during a short time ? A disk full of a liquid turns at a constant angular velocity w around the red axis. At a time, a valve move out, this will increase quickly the pressure inside the liquid. 1/ Draw the lines...