Fluid dynamics Definition and 643 Threads

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 Trying to figure out how faucet aerators work–currently designing an experiment. I'm going to use plastic mesh with different sizes of holes for the screen. The smaller the total area of flow the more restricted the flow of water, yeah? Because more air is added to the flow...

Hello,I am trying to calculate the velocity in a pipe with length L and Dia D, which is connected to bottom of a pressurized vessel (Vessel dimensions are known, Level of liquid inside the vessel is known). Now i need to figure out the velocity as a function of pressure inside the vessel.We can...

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...

Hey! :o I am looking at the conservation of momentum. The force at $W$ from the tensions at the boundary $\partial{W}$ is $$\overrightarrow{S}_{\partial{W}}=-\int_{\partial{W}}p \cdot \overrightarrow{n}dA=-\int_{W}\nabla p dV$$ where $p(\overrightarrow{x}, t)$ the pressure and...

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, 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...

Homework Statement A water storage tank is open to air on the top and has a height of 1 m. If the tank is completely full and a hole is made at the center of the wall of the tank, how fast will water exit the tank? Homework Equations Pressure is the same as atmospheric pressure because the...

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 have been told by my teacher that the surface of a fluid is always perpendicular to the net force acting on it. The reason being a fluid can not withstand tangential stress and if a shear stress is applied to it, it will slip until the surface becomes perendicular to the net force. So my...

So I was reading about Vortices in Wikipedia, when I stumbled upon the explanation about Irrotational Vortices. It states there that in Irrotational vortices, the fluid's flow velocity u, is inversely proportional to the distance r, from the vortex's axis. Then, at the end of the...

Homework Statement The Plimsoll line is a line marked on the side all ships that effectively indicates the safe maximum load the ship can carry in that type of water at that temperature.You have been asked to stand on the dock and collect the tickets of the passengers boarding a cruise ship...

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?

Hello, I'm a PhD student in medical biology and am doing experiments with bloodvessels. I've modified an existing technique and getting unexpected results (ofcourse..). I think it is due to a pressure difference but my knowledge of physics is inadequate to be sure. Ill give a short explanation...

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 am thinking of burying a 3/4" water line which is tied into my outdoor 1/2" house spigot line. This buried line would run about 100' to where I can better use it for washing a car or irrigating a flowerbed. My question is: by taking the new addition of water line from a 1/2" feed water line...

Hey all, I’ve scoured the internet in search of an answer to no avail, so it’s time to ask the experts!My background is more Chemistry and Biology, not Physics, or specifically fluid dynamics, so bear with me! Also, this is a little long, so I will do my best to make it easy to follow.The...

I had to detect a Leakage in my pipe ,and i am really confused whether the Darcy Weisbach or Hagen-poiseuille equation will be satisfied by the current criteria ,as described below: I have a main tube with ends A and B and various outlets,suppose n outlets are present between A and B , I have...

1. Homework Statement Homework Equations CFD The Attempt at a Solution I'm a bit confused by this question. So at first what I do for the problem on the left, I find the changes in the velocities in X and and Y on all four sides. I notice that the values on the diagram to the left are...

Consider a partially filled bottle of water. When it's tipped over and rotating about its pivot point where its edge touches the ground, it has an angular acceleration. Assuming the liquid is not viscous at all, so flows perfectly, at a given instant can it be considered to have a moment of...

Homework Statement Homework Equations Conservation of linear momentum for fluids The Attempt at a Solution This seemingly simple problem has me confused. First of all, I want to set up the sum of the foces as: -Min + Mout -Fx = 0 So first of all, not only does my Fx term have the wrong...

Any thoughts on this book? I'm interested in a fluid mech book for physicists, this one looks good but I can't find any reviews on it. You can suggest other books as well, as long as they have available new editions.

Hi, I'm attempting to do a question involving blood flowing through a blood vessel and I'm incredibly stuck and would appreciate some help. The question is as follows: 'A simplified model of blood flow through the human body makes the approximation that the flow I is proportional to the pressure...

Homework Statement Determine the speed of a fluid particle at the origin and at a point (1,-2,0) for each of the following velocity fields when t = 2s. All distances are in meters and t is in seconds. V = (x+2)i + xtj - zk m/s Homework Equations V x dr = 0 dV/dt = u(dV/dx) + v(dV/dy) +...

Hi everybody, my question is not properly about CFD but mainly about Fluid Dynamics itself. I have performed a RANS simulation of a round jet of methane and air and now I'd like to compare those results to some experiments. Unfortunately there aren't papers about experimental data for...

So this is probably a very basic question. I'm studying EE so this is kind of out of my field as i have never taken this but I'm working on a project and it involves a pressurized container releasing air into a tube and launching something out the nozzle. The problem I'm having is that I'm not...

I am working on a problem in which viscous flow comes out from an inclined tube, forming some kind of a fountain. In the tube the fluid is Newtonian and the flow can be treated as Poiseuille flow. I want to study the movement of the fluid after it leaves the tube. Can someone point me about the...

Homework Statement "Inverted siphons were used by the Romans to cross some valleys. If the height difference between the top of the valley and the bottom is 10 meters, the pressure in the pipe at the bottom of the valley will be ____. Homework Equations Bernoulli's Equation P1+(pv^2)/2 + pgh1...

Hello everyone! 1. Homework Statement I want to model the irradiance on a fluid element while it is flowing, from a fixed(above or below) light source that has an irradiance that shows first order decay with time and from x-naught to x-infinity . here are the assumptions: -Laminar flow at...

Homework Statement [/B] (a) Show that for an incompressible flow the velocity potential satisfies ##\nabla^2 \phi = 0##. Show further the relation for the potential to be ## \frac{\partial \phi}{\partial t} + \frac{\nabla \phi \dot \nabla \phi}{2} + \frac{p}{\rho} + gz = const.## (b)Write out...

I'm designing a testing unit where I need to estimate the smallest diameter of a short complex pipe (around 1 meter, three bends and some diameter viariations). Since the pipe is being cooled down in a water bath after production, my idea is to force water with a known pressure in one end of the...

I completed 4a successfully, and with 4b, i have 2 queries: a)why can't I let Reynolds # equal to 2.19 x 10^5 (from part a) then simply sub v=4 instead of 5m/s and rearrange for viscosity? I tried it this way first and got a very wrong answer. Why do we, essentially, need to work backwards to...

see I worked through 3a) and I was comparing answers, I saw that they omitted v2 (5m/s) their explanation was because it was "defined in the question" I'm not sure what that means 3)b I tried understanding what's going on but I am clueless unfortunately, how exactly did they get 12.1m ? Where is...

Hello :) My question concerns a control volume with a changing area. The momentum equation: p1A1-p2A2 = ṁ(V2-V1) is applied to the control volume. The image shows the equation found when applying the above momentum equation to the control volume: The bit I'm having difficulty with is the part...

What happens when you have more than one hole in a vessel containing liquid? Can you help me finding the velocities at different holes if they are at some height from level of liquid at a particular instant? I know what happens when you put a small hole in a tank containing liquid at a height h...

If I have an object of mass m tied to the lower surface of a vessel having a liquid and the vessel accelerates upwards... From FBD of object, Buoyant force acts upwards, mg down, pseudo force downwards (frame of reference is vessel) T down. Here's the doubt. Why is F(buoyant force) = Vp(g+a)...

If I have a U-shape wire frame and it contains a straight sliding wire and I dip this in soap, a film forms between the sliding wire and the boundary of U shape frame. Why is the force due to surface tension F = 2Tl where l is length of sliding wire? They say there are 2 layers in contact...

I was doing some research into my coursework (don't worry, this isn't a real 'help!' thread) on Stokes law, and I found this equation on this forum (posted in 2010), regarding the effect of the walls of a pipe on the calculated value for viscosity when a sphere is dropped through that pipe...

Are there any good books related to the not much popular De Broglie-Bohm pilot wave theory? There have been recent studies on dynamics of the walking droplets relation with pilot-wave dynamics to describe the motion of quantum particles.

Good Evening to everyone! I'm currently a student of theoretical physics. I have a Bachelor Degree in Physics and I'm from Italy. When you finish your B.D. you can choose to go on with your studies in order to get a Master Degree (other 2 years of study) and here you can choose your curricula...

I am about to graduate with an aerospace engineering degree. I am planning to go into grad school for Applied physics(probably plasma physics), which I find very interesting. But the main reason I joined the aerospace degree was because I was interested in CFD. But since I could't land any...

Homework Statement A vertical jet of water of 3cm in diameter impinges upon a horizontal flat plate with a velocity of 4m/s, and all of the water spreads out horizontally. Find the force exerted on the plate. Homework EquationsThe Attempt at a Solution I am not 100% sure how to tackle this...

Homework Statement [/B] The shape of a car windshield is approximated in the figure below; its length is 2.0 ft and height is 1.5 ft. Obtain an equation of the windshield shape r as a function of θ, r(θ), in the polar coordinate system shown in the picture. When the car moves at 55 mph...

I want to go to physics grad school, but I also want to be ready to go to into CFD for industry if academia doesn't pan out - what area of physics would prepare me best for that?

I'm currently working on a project about wind speeds, and have come across a roadblock due to my limited knowledge... So I really hope you guys can help me out. When you light a campfire or candle, the heat from the flames cause the air around it to rise, which leaves a "vacuum" for colder...

Homework Statement [/B] http://imgur.com/TQf2TNP http://imgur.com/TQf2TNP Diagram for the porblem For this problem, you may assume the following: • The mass flow rate of water through the jet pump is always the same. • The combined mass of the rider and jetski is 450kg • The time dependent...