Fluid dynamics Definition and 609 Threads

<< Thread moved from the technical forums so no Homework Help Template is shown >> Hello, I'm attempting an experiment where I take a cart and slide it down a ramp. Each time, I will coat the ramp with a different liquid. I want to compare the effects of the dry ramp, a ramp with water poured...

Hi, I'm a newbie at Comsol and want ask for guide how to fill something with fluid and make sphere rotate. My goal in creating system where one sphere contains second. Second sphere rotates on its axis. Volume between is filled with fluid. I understand how to create spheres, but couldn't...

Homework Statement ρ= density, vi = i-th velocity component, gi=i-th component of gravity vector, p=pressure, μ= viscosity, D/Dt = material derivative Homework Equations Continuity equation: div v = 0 The Attempt at a Solution

This is a problem for a fluid dynamics class I'm in. My current approach is to use a conservation of mass approach and say that the d/dt(momentum in the cart) = momentum into the cart. This leads to (u is speed of the cart, V is volume J is jet velocity, A is cross sectional area of the jet)...

Why does the planetary boundary layer velocity profile shows a sinusoidal variation with height? Reference: Fig:14.10 Page 576 Fluid Mechanics - Kundu and Cohen 2nd edition

Moving fluids are generally in a state of non-equilibrium. However, in fluid dynamics, people generally assume a state of local thermodynamic equilibrium and argue that in such a condition, equilibrium thermodynamic concepts such as pressure, temperature, entropy, internal energy etc. can be...

I am trying to calculate the flow in a system from an underground tank up through a pump into a vessel. But cannot find or derive a formula that yields a good result, I don't think I can use the same head calculations as Velocity will have changed. 1. Homework Statement ρ = 1000 kg m–3 μ =...

Homework Statement A 1m^3 steel cube is to be floated on mercury (specific gravity=13.6). On each side of the cube there is a 5mm clearance. Assume that the container is open to atmospheric pressure at 100kPA. Find the mass of the mercury. Homework Equations P=F/A The Attempt at a Solution I...

If you have an non-viscous incompressible fluid flowing in a pipe whose static pressure is higher than atmospheric pressure, then after exits the pipe will the dynamic pressure increase? The static pressure of the fluid right after exiting should decrease because it should be equal to the...

Homework Statement A tank with a 25.5 litre capacity contains air compressed into 355 atmospheres used to drive a torpedo by expansion into an engine via a pipe of diameter 0.08cm. A mechanism ensures that the gas flows to the engine at a constant rate and any cooling of the air during...

Hi all, I encountered a fairly straightforward problem involving fluid dynamics, but the result I got is very confusing and I seem not to understand where I got wrong. This is the question: A rectangular flat-bottom barge with a bottom area A=50 m2A=50~\text{m}^2A=50 m2 is loaded so that the...

I am currently doing a research project in the attenuation of pressure waves. With an focus on dealing with sonic booms the are generated from high speed train tunnels. my experiments involved pressurizing a cylinder then using a rapid release valve allowing the air to escape along a pipe. I...

Hi, I am designing a system to cool aluminium through contact cooling. I have a steel die with 9x 20mm diameter cooling chambers. Water is pumped through the chambers which cools the steel die and hopefully the aluminium sitting on top of it. I am looking to find the temperature of the...

Hi all, I am soon starting a research project into Earths core dynamics, and will be using a pre existing code. I understand the principle of DNS and resolving for all different resolutions. But I do not really understand how to implement that efficiently. Does anyone have any good resources...

Consider a small rigid spherical particle of radius a, fully immersed in a viscous incompressible Newtonian fluid of shear viscosity η above a hard-wall with stick (no-slip) boundary conditions, located at the plane z = 0. A constant positive (external) torque Tx is applied on the particle. My...

Hello, I have a general question regarding energy coupling in multi phase flow. My question comes is based on the text from this book...

Why is the pressure used in flow work the pressure of the fluid? If the fluid was say at 10kPa and the external pressure was at 0Pa, why don't we use the 0Pa in our calculations for flow work, since it's the external pressure that's the resistance? Or is it not possible to have this difference...

Homework Statement Homework Equations The Attempt at a Solution I tried a few different things, they all involve finding u and v components of velocity. I know the stagnation point is at y = 0. I also know that at stagnation u = v = 0. If I get the velocity magnitude and set it equal...

Homework Statement Homework Equations The Attempt at a Solution I don't even know where to start. I don't understand the question.

Background: I am taking an undergraduate fluid mechanics class. I seem to have a misunderstanding with my interpretation of Reynolds Transport theorem (RTT), which I have written below: $$\frac{DB_{sys}}{Dt} = \frac{\partial}{\partial t}\int_{CV}\rho bd V +\int_{CS}\rho b \vec{V}\cdot...

Homework Statement Determine the depth of the flow of channel if the best hydraulic channel is needd for composite channel in figure to convey flow rate of 6.5(m^3/s) , Manning coefficient n on bed slope are 0.015 and 0.0015 respectively . Homework EquationsThe Attempt at a Solution I assume...

Homework Statement This is not so much a homework problem but a question I have on the subject while studying. I have a terrible teacher who is contradicting my textbook constantly and I really want to learn this. Is a pressure field vector or scalar? If given the velocity components, is...

Hello everyone! I am currently having some real issues estimating the power requirements for a concept vehicle's Air-Conditioning System, and I mean I've been going over this on and off for the better part of a fortnight. At this stage I feel like I have fried my brain and have no idea if I am...

Why a fluid jet becomes unstable only when the wavelength of the perturbation exceeds the value of jet perimeter? Do you imagine any physical reason behing this?

This is something I do not know how to explain. Although velocity decreases due to friction with ambient air, momentum should be conserved and, therefore, it entrains mass. What is the reason that momentum should be conserved?

I am graduate student from structural mechanics of solids and need to learn 1 course from fluids and thermal group which includes fluid mechanics or thermodynamics+heat transfer. I am unsure which one would be better to learn, especially which would be helpful in future for solid mechanics. Can...

Can someone smarter than I, please express p1 and p2 in terms of f, or v and r? The pump pushes out water at f rate which creates velocity v in the bigger pipe. When the water comes to the restriction velocity increases while flow rate is conserved. Bernouli tells us that the change in...

1. Can a fluid which is accelerating down an inclined channel with constant acceleration still satisfy the continuity equation for a constant-density fluid? Since the acceleration will be down the slope, in the streamwise direction, then surely ∇⋅U > 0? 2. Assuming that continuity is satisfied...

In an electrical high pressure water motor or pump what is the main cause of energy loss. Originally I was thinking along the lines of 1st heat/electrical losses in motor. 2nd Friction of the water in pipes. 3rd noise. But I'm torn between the first 2 ? Tho

I have a weird question here. At what speed does air flow from a pressurized container at one atm into vacuum (rupture in ISS for example). I was watching the Martian and I wanted to see how much deltaV Mark Wattney can get by puncturing his suit, so I did my homework and saw that the spacesuit...

Homework Statement In a low-flow showerhead that contains 18 nozzle holes, the volume flow rate of the water is 4.00 L/min and the water maximum speed is 2.70 m/s. What is the diameter of each hole? Do not ignore viscosity of water. Homework Equations Q=Av_max Q=((pi)r^2)v_max...

Homework Statement A hollow stirrer that has a diameter of 2.0 mm is inserted into a cup of water at 20∘C. The surface tension of water at that temperature is γ(surface tension) = 7.28×10−2 N/m. What is the mass of the water supported by the surface tension in the stirrer? Given: d=2 mm...

Homework Statement so I have been working on this problem : Diameter1 at wide end: 8cm || V1 = 1.56m/s Diameter2 at narrow end: 3cm || V2 = 11.094m/s Force exerted on plate = 87N Find the manometer reading Picture below: Homework Equations P1+(1/2 ρv1^2)=P2+(1/2 ρv2^2) 1 − 2 = (2 −1)ℎThe...

I have a diagram similar to the following. Water entering the larger end is at 20degreesC. The larger end has a diameter of 8cm and Area 50.26cm2. The small side has a diameter of 3cm and Area 7.0685cm2. The water jet exerts a force of 87N on a flat plate at an unknown distance. Assuming no...

I am aware of only two fields where the renormalization (sub)group ideas can be systematically and unambiguously applied: particle physics and equilibrium critical behaviour. 1.- Are there any others? 2.- What are these ideas used for in fluid mechanics? 3.- When cosmologists speak about...

Hello, does anyone know if a solution to EFEs (Einstein's Field Equations) has been found that's analogous to Helmholtz's vortex ring solutions in fluid dynamics?

Picture water flowing in a duct. In these kinds of scenarios, the loading exerted by the moving fluid to the solid in the perpendicular direction is often taken as being equal to the pressure of the fluid at the wall. I agree that the above assumption is true for a stationary fluid. For a...

I saw the DAPL news story about the oil pipeline and I realized I have no idea how to analyze the problem of a fluid flowing from a boundary into granular material (or however you would classify soil). Does anyone know of any book or website that discuss the governing (or approximate) equations...

Hoping to get an intuitive idea of the derivation behind the Rossby number that isused in fluid mechanics(atmospheric and oceanographic sciences). I know what it is and how it is used but I want to know Rossby hit upon the idea of the number that is named after him...

1. The problem statement, all variables and given/known d At what speed, the velocity head of water is equal to pressure head of 40 cm of Hg? (1) 10.32 m/s (2) 2.8 m/s (3) 5.6 m/s Homework Equations v^2/2g = p/rho*g (velocity head= pressure head). The Attempt at a Solution since pressure head...

In fluid dynamics there is a duckbill check valve to prevent the reverse flow. In EM wave an antenna emmits/receive at the same efficiency. Is there anyway one can make a check valve for antenna so that it emmits more than received or vice versa...or perhaps emitts without even receive?

Homework Statement [/B] Water rises in a capillary tube to certain height such that the upward surface due to surface tension is balanced by 7.5 X 10-4N Force due to weight of the liquid. If the surface tension of water is 6 X 10-2Nm-1,the inner circumference of the capillary must be Homework...

I need 250 m/s of airflow speed in a wind tunnel. I can assume for this purpose, the test section of the wind tunnel has uniform flow. However, the wind tunnel can only generate a flow rate of 100 m/s but the pressure can be increased. I am drawing a blank on how could a generic boundary layer...

Hello! 1. Homework Statement I need to find the instantaneous height of a liquid during the simultaneous filling and emptying (through a hole) of a cylinder. I have varying Qin at incremental time of 1 sec. with cylinder area=5 cm and orifice area=0.5 cm. Homework Equations Torricelli's...

Homework Statement Problem in attached image Homework Equations $$P_1+\frac{\rho v_1^2}{2}=P_2+\frac{\rho v_2^2}{2}$$ The Attempt at a Solution I understand everything in the solution except why $$P_A-P_B=h(\rho_{Hg}-\rho)g$$ Why do we have to subtract the density of water from that of...

I am intending to design a CD nozzle that produces 20mN thrust under atmospheric conditions. The reservoir pressure will be 1.4 bar, and the ambient pressure will be 1 bar. The other variables are adjustable. This will in the end be sent out for fabrication.My process is as follow, May I know...

My son today asked me for an analysis of a situation, which was described to him as being purely anecdotal but apparently a fairly widespread belief among bartenders, so possibly correct. The description is that if you take the two metal halves of a cocktail shaker, with a normal compliment of...

Hi everyone ! I'm currently working on a project for which I need to measure the advancing contact angle of a liquid on a solid, specifically the advancing contact angle of a molten thermoplastic on carbon fibers. My understanding is that there is a difference between dynamic contact angles...

To start this question off, I'll just state what I do understand about potential flow theory 1.) I understand that the navier stokes equations are really difficult to solve analytically except in degenerate cases where the assumptions about the flow cancel out the non-linear terms. 2.) I...

Homework Statement This is not a set question but a problem statement for an investigation. I am trying to understand the physics behind drinking through a straw, but not when the straw is fully submerged in the drink but at the end of the drink when the liquid and air both pass up the straw...