Fluid mechanics Definition and 698 Threads

Hey guys. I could use some explanation since I am new to FM: So my problem is the following one: Fluid flows with an average velocity 8 m/s in a pipe with diameter 3m. What is the volume flow rate? Now, I think the formula I got to use is Q= v.A Yet, I found my solution from a formula I found on...

Homework Statement So, I need to find the X and Y components of the force in the T section Homework Equations Due the fact that the problem dosn't ask for a specific force I couldn't think in any other equation to use, because even tough there is Pressure and Gravity acting I need to...

This is more of a concept question; if I choose different repeating parameters to someone else, say my lecturer, and got different pi groups to him/her, however my groups are still dimensionless (i.e. the units for each pi group cancel to 1), is my answer still correct?

Homework Statement Consider an aircraft turbine as in the figure below. In the reference frame of the turbine, air of density ##\rho_0## comes into the turbine with speed ##U_0## through the entrance with cross sectional area ##S_0##. In the combustion zone, air is mixed with the fuel and...

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

I'm studying the Navier Stokes equations right now, and I've heard that those set of equations are invalid in some situations (like almost any mathematical formulation for a physics problem). I would like to know in which situations I cannot apply the NS equations, and what is the common...

My native language is not English. I follow a series of vids about Ansys Fluent. I am not stuck in 2.59 about the part "so VR" and "so we are in a velvet in laminar regime." Would you please explain those parts. This is about my project and it is about calculation of pressure losses in pipes in...

this is a float submerged in fluid the upthrust is greater than the weight. P=ρgh to calculate the pressure should I use the total length of this object as h? Homework Equations P=ρgh Fb=PA (A=area) The Attempt at a Solution Curious to know whether I should use the total length of this object...

Hi I'm trying to understand a paper that approximates the solution to Burger's equation (1D Navier Stokes) by a doing a one-dimensional cellular automaton simulation. I'm having a hard time understanding how all these topics connect. I have seen and walked through various demonstrations that...

Homework Statement Calculate head required for the pump and then its power requirement assuming 70% efficiency. The lower storage vessel is vented to atmosphere (assume 1 bar pressure) . I have the following given information: Pipe Area = 0.00636m^3. Flow(Q)= 0.01m^3/s Average Velocity =...

Hi, I have never found a satisfactory explanation for why the Bernoulli equation is not valid when the streamline passes through a turbine, pump or another work transferring device. I have read many books that simply state this limitation without providing a convincing reason. Bernoulli...

I encountered this statement on my lecture notes today, I don't understand why compressible flow needs to have another constraint of energy equation while incompressible flow only satisfies continuity and momentum equation. And how is this energy equation related to the speed of sound?

I 90% understand the question and solution but unfortunately I have some hesitations about the formal solution in the book. First of all, when calculating P4-P3, choosing lines and points on them, why do book assume velocities of 3 and 4 to be the same...

Hi, I stamped at a series expansion. It is probably Taylor. Would you explain it? It's in the vid. https://confluence.cornell.edu/display/SIMULATION/Big+Ideas%3A+Fluid+Dynamics+-+Differential+Form+of+Mass+Conservation I understand equation 1 in the picture but I do not understand 2. I...

Hello, I got this stream function ψ(r,θ)=sqrt(r)*sin(θ/2) I have to draw the streamlines of this fuction, however, I'm not sure how to afford this, should I consider this just like a normal function that depends on tetha and rho, or it's more like a polar plot? When i drew the streamlines...

I'm now taking classes on mechanical vibrations and fluid dynamics, and those are two fields that are very interesting to me. I've always liked the subject of aerodynamics, but now I'm really liking to study mechanical vibrations, very interesting field of study. I'm looking for some specialty...

Hi all, I study Mathematics and Theoretical Physics at university. Next year, I'll have a choice between three modules; Thermodynamics and Statistical Physics Cosmology Fluid Mechanics My main interest is Condensed Matter Physics; therefore, thermodynamics and statistical physics is a given...

Hello there. I took a test yesterday in my thermal fluids 1 class and I was hoping somebody could confirm or critique my answer. (Don't worry, I asked the professor first if I could take the picture) The problem is: Water is pumped from a lake to a pool through a 0.05 m diameter pipe. System...

I'm an engineering student, one of my task is to search the best orifice type for pressure drop. I have no idea which one would it be since I believe that the beta ratio is the one that would determine the best orifice for pressure drop.

Hello, I'm a physician with special interest in cardiovascular physiology. I'm trying to comprehend the basic physics of the cardiovascular system. Here's my thought process - Simply stated - the heart muscle contracts, thereby causing a reduction in the cardiac chamber volume and release of...

Hi all, I have a little problem while reading Feynman lecture note volume 2, chapter 40, section 40-3. In that section Mr Feynman talked about Bernoulli equation and a example of a filled water container. In high school we learned that if we drill a hole near bottom of container, we can get...

Suppose a container is full of water is placed over a weighing machine. Now a ball is hanged with massless string but dipped inside the tank and ball is not touching the bottom. What will be the new reading on the weighing machine?

Homework Statement The uniform 5 m-long round wooden rod (ρ = 800 kg/m3 ) is tied to the bottom by a string with length 1 m. Determine the inclination angle θ if the water level is 3.5 m. What if the water level is 7m? Homework Equations Fb = ρgV The Attempt at a Solution So I'm really...

How does the velocity at an elemental height h equates to √(2gh)? My application of Bernoulli's equation is not yielding the result. Please show the process. Thank you

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...

Hi! I'm looking for a somehow "serious" textbook about fluidmechanics, something like the book by Kundu-Cohen...a book talking about it without by-passing the math involved (tensor analysis) like many books do! Thanks

Homework Statement A block has dimensions 0.015 x 0.2 x 0.1 meters and weighs 6 Newtons. A 15mm-diameter jet of water is deflected by the block. Find the flow rate needed to tip the block. Homework Equations Mass conservation: ∂/∂t ∫(control volume)ρ d∀ + ∫(control surface) ρv•n dA = 0...

Homework Statement I need to find the pipe diameter or mean velocity. Q= 0.01m^3s Density= 960kg m^3 Viscosity = 0.081 Pa s Max Velocity = 1.8 m s Homework Equations Mean velocity= 4Q/pi.D^2 The Attempt at a Solution I have two unknowns in this equation so I'm unable to find D or Mean...

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

When solving for the hydrostatic force on a surface we use the height to the centroid(hc), then when using the point of application we use the y coordinate of the centroid(yc), however shouldn't they be the same since they both start from the top surface and reach down to the object surface on...

Hello, please see attached text below - this concerns ''rigid column theory''. When a valve is closed, the pressure rises at the valve; the pressure rises above the reservoir pressure by ΔP with a height increase ΔH above H. When the valve is opened, this right hand pressure will disappear and...

Hello Please see attached page from a textbook. Can someone explain why H = 4f.le.vo^2/2d.g and why delta H is given by the expression in the book? Note that the figure it mentions is on the top of the page. I have tried for days here. Thanks

I ever read that there is no meaning for quantizing fluid mechanics. While left hand side of Einstein field equation used fluid-like approximation for matter (momentum-energy tensor). Therefore, if the first statement is correct then there is no meaning for quantizing gravity, right?

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...

For my senior design project, my group is tasked with creating a wind turbine. At the moment, I am trying to figure out what approximate RPM the blades will rotate at so we can select an appropriate gear ratio and generator. Our advisor instructed us to use conservation of momentum on the...

Homework Statement [/B] A rectangular object has a width of 40 meters, height of 15 meters, and length of 2 meters. It floats consistently when 3 meters of its height is below the surface of the water. 1. Find the volume of the displaced water. 2. How much is the buoyant force on the object...

So, here's the problem I've come up with that I wanted to solve. We're going to be using a polar coordinate system for this one. A will represent our angle theta, and r will represent our radial coordinate. We are going to be looking at a non-compressible Newtonian viscous fluids. I'll now put...

Hello, So I was reading wikipedia the other day, as I do from time to time. I came across a rather interesting sample problem posed in the article, but seeing as Wikipedia is horrible in some of their physics articles on explaining what's the hell they're doing, I became lost. Here is the...

Hi, I'm looking for a modern, colourful, illustrative introductory textbook to work through on tensor calculus/continuum mechanics. I'd like one with lots of physical examples, exercises, summaries, etc. I'd like an emphasis on engineering. Something in the mould of Frank White's Fluid...

What is the difference between an automotive spoiler and an automotive wing? Is there a difference? My understanding has always been that a wing is an airfoil, and is used to produce downforce, while a spoiler is is just a lip that is used to reduce drag by creating a pocket of stagnant air...

Homework Statement A reasonable approximation for the two-dimensional incompressible laminar boundary layer on the flat surface in Fig. P4.17 is u ≈ U(2*(y/δ) - 6*(y3/δ4) + y4/δ4) δ = Cx1/2 where C is a constant y ≤ δ Homework EquationsThe Attempt at a Solution Incompressible so...

After doing extensive research, I am still confused about Control Volumes. Say that there is water flowing into a cup at a steady rate, and I am required to illustrate the momentum and mass flows, as well as the forces, how would I approach this? I have seen examples of Control Volumes but they...

if the person sitting in the boat throws a pebble to the swimming pool. Pebble was initially contained inside the boat and of course it has higher density than water.

I'm working on an idea in product development, though being still a fairly new student in this i still am left with a lot of questions, perhaps anyone can aswer? Say that i have a closed can with pressurised water lying in a pool of water. My question would be what the best method would be for...

why does the pressure drop equation derived for the laminar flow has no parameter to indicate the surface roughness of the material of the pipe,unlike the turbulent flow !

1. Homework Statement See image. Homework Equations I thought that Fx=p*u1*A1(u1+u2)+(p1*a1)+(p2*a2) would be the correct formula however I cannot seem to get the stated answer of 1.8kN. The Attempt at a Solution Using the above formula, p1v1=p2v2 to find u2 and p1a1=p2a2 to find p2...

If I'm designing an injector for a rocket engine, I have a specific mean flow rate (m/s) that must be met due to the pipe diameter and the required mass flow rate. I've calculated all the pressure drops due to lost work from friction, valves, and orifice geometries (not from change in area, but...

Hello everyone, The boundary condition : P=0, z=ζ is very common when studying irrotational flows. When cast with the Bernoulli equation, it gives rise to the famous dynamic boundary conditionn, which is much more convenient : ∂tφ+½(∇φ)2+gζ=0, z=ζ But what happens if the motion is rotational ...

Hello every body, I am very excited to be now part of your community. Me in a few words : I am french PhD student, working in the field of physical oceanography for 2 years now., more specifically on the wonderful topic of ocean surface waves. I am particularly interested in asking you some...

Hello, PF! I'm currently brushing up my fluid mechanics and came across some questions while studying the compressible flow of an ideal gas using Bernoulli's equation. First, consider incompressible flow in the following system Neglecting any changes in elevation, the Bernoulli equation for...