Fluid Definition and 1000 Threads

Homework Statement A cube of side 5cm is placed in a fluid. For the following velocity values, calculate the average divergence of the flow. Is there a source or sink within this box? The velocities are given in cm/s. The cube is oriented so that the +z axis exits the front face, the +x axis...

The basic idea is to package an egg so that it will not break when I drop it off a roof (assume 10m tall). The packaging should be as small and lightweight as possible. I know using a fluid will be rather heavy, but I'm still curious about his. How would I determine the optimal fluid to use? I...

Hi, I'm looking at the solution to a question on fluid flow through a rigid pipe. Original equation: \mu u = 0.25r^{2} dp/dx + Aln(r) + B After applying boundary conditions: \mu u = 0.25dp/dx (r^{2} - a^{2}) I don't understand how the constants have been solved for. Below is as far as I get...

Hi all, For an exam I'm required to be able to plot the PDF of a fluctuating velocity function, say u(t)=sint(wt), using what they call the "graphical technique", but handily I can't find it anywhere in the lecture notes, and I'm struggling to find anything with a standard Google search...

I've rencently been thinking about several systems related to fluid mechanics, and I've asked myself the following question: If I have a cylidrical tank with a small hole in the bottom (the surface area of the hole is small in comparison with that from the tank) and I'm filling the tank with...

Hi. I was asking myself the following question. What happens if I have a fluid at rest inside a container, and I introduce my finger in it without applying any force to the walls? Will the weight of the whole system change? My intuition says no (If I don't exert a force on the fluid this...

Need help on basic fluid volume calculation! Hey guys, I need some help calculating a volume. Ok, so say we are given a pressure vessel with an 88ci volume @ 4500psi which is then regulated down to 100psi and we open a valve for 0.1 second. How many cubic inches of air would be released...

hi all,i have recently started studying a subject heat transfer,in which i learned that there are two types boundary layers.one is velocity boundary and other is temperature boundary layer..now my question is that..boundary layer thickness increases in flow direction,what is the physical...

Homework Statement A shaft of diameter 74.9mm rotates at 1400rpm in a bearing which is of diameter 75.03 mm and 75mm in length. The annular space between the shaft and the bearing is filled with oil of viscosity 0.096 kg/ms.By assuming a uniform velocity gradient in the oil, determine the...

1. The problem statement... The textbook I am using states that an idealized fluid cannot sustain a force tangential to its surface. Can anyone expound upon this argument? This statement is an introductory exploration of pressure and is cited as the reason that the force dF exerted by its...

I am interested to know what book(s) others would recommend to someone aspiring to learn fluid mechanics from and what kind of preparation would be required for that book. I am an undergraduate student and have completed courses in single and multivariable calculus, linear algebra, ordinary...

fluid mechanics: defition of "shear flow" [rate of deformation tensor] I'm studying old undergraduate chemical engineering notes for an exam in grad school. Can't recall what this really means, can anyone explain to me what "off-diagonal elements" means and why the trig function velocities...

This may sound like a basic question, but it's just to get it clear: When describing fluid flows, does the term "incompressible" mean exactly the same thing as "constant density"? I was under the impression that if a fluid cannot be compressed, then its density must remain constant for any...

QUESTION Rainwater collects behind the concrete retaining wall shown in the figure. If the water saturated soil (specific gravity 2.2) acts as a fluid, determine the force and center of pressure on a 1-m width of the wall. PROBLEM 1. What does it mean by 1-m width of the wall? Is it 1-m...

Hi, I am trying to work with the problem of keeping a solid body at equilibrium over an orifice. To see what I mean ( not necessarily a sphere could be a cube or something like that as well ) please look at the image I have attached. I am trying to work with the sphere case first and then...

Homework Statement Consider a bucket quarter filled with oil. When the bucket is rotating with the angular velocity ω, derive the equation of the surface h(x), where h is measured from the lowest of the surface and x is measured from the rotational axis. Does it change if we replace oil by...

Hi, I am a mechanical engineer, therefore I am no very experienced in chemistry I need to find a fluid similar to lubrificant oil in density and viscosity, but with low oiliness I thought to gasoline, but it is very dangerous for my aim. I have to test on the production line some components...

Homework Statement A cork is held at the bottom of a bucket of water by a piece of string. The actual depth of the cork is 0.713786 m below the surface of the water. If the density of the cork is 157 kg/m3 and the volume of the cork is 3 cm3 , then what is the tension in the string...

Hi all, I know that for low speeds, the fluid resistance is F=kv while at high speeds, it's F= Dv^2. However, how do I ever know what is defined as a low speed and high speed? This kind of explanation is so qualitative and I think a quantitative one is better. Thanks all!

I've been attempting my Physics homework and realize I have no idea how to do any of the problems. Instead of asking each of them, I figured I'd ask if anyone knew where I could find a general lesson plan for this section. Here are some of the problems. All help is appreciated :). 1) A...

You have this loop of water (or some other "incompressible" fluid) with a nuclear powered water pump that constantly pumps the water in a circle. This loop is slowly lowered near the event horizon of a black hole, let's even make it a super duper massive black hole to minimize tidal effects...

Homework Statement water in main pipe at the street level is at a gauge pressure of 170 KPa and is moving with neglibible speed. A pipe connected to the main pipe is used to deliver the water to kitchen located on the third floor of a building, at a 15-m height from the street level. what is...

I'm just a bit lost on how to find the change in pressure. I've posted a picture of my work thus far.

Hello, and thank you kindly for considering my question. Background: Medical needles come in gauges such that a smaller gauge represents a larger needle. Scenario: Doctor Jack says "18 gauge needles are best for this procedure", but Doctor Jane says "27 gauge needles are best because...

Homework Statement Hi guys, I'm pretty new here, and long story short, I'm struggling a bit on a fluid mechanics question I've been doing for some revision. A shaft 70 mm in diameter is being pushed at a speed of 400 mm/s through a bearing sleeve 70.2 mm in diameter and 250 mm long...

Homework Statement Liquid 1 (density ρ_{1} = 8290 kg/m³) is poured into a large open cylinder to a depth of d_{1} = 85.9 cm. Liquid 2 (density ρ_{2} = 5695 kg/m³) is then poured on top of liquid 1 to a depth of d_{2} = 70.3 cm. Then liquid 3 (density ρ_{3} = 2933 kg/m³) is poured on top of...

Homework Statement A velocity field is given by \vec{V}= [Ax^{3} + Bxy^{2}]\hat{i} + [Ay^{3} + Bx^{2}y]\hat{j}; A=0.2 m^{-2}s^{-1}, B is a constant, and the coordinates are measured in meters. Determine the value and units for B if this velocity field is to represent an incompressible flow...

Hello there , could you please explain to me what would happen to an inviscid/viscous incompressible flow (energy,momentum and entropy wise)falling from a height ? ( i.e a dam ) Thanks;)

Homework Statement A large cylindrical tank has a hole of area A at its bottom. Water is poured in the tank by a tube of equal cross-sectional area A ejecting water at the speed v a)The water level in the tank will keep on rising. b)No water can be stored in the tank. c)The water level...

I am trying to come up with a shape or design of a simple piston with holes that will allow fluid to flow in one direction better than the other. Very Simple shock design. I have tried tapered holes so as to speed up flow in one direction and it worked slightly but haven't quite found the...

Homework Statement A piece of wood is floating in water kept in a bottle. The bottle is connected to an air pump. Neglect the compressibility of water. When more air is pushed into the bottle from the pump, the piece of wood will float with a)larger part in the water b)lesser part in the...

This is the question The flow of a fluid between two large flat parallel plates normal to the y direction is fully developed and steady. The plates are a distance 2h apart in the y direction and the velocity profile, assuming y=0 is at the midpoint between the plate is V(y) = V_0(1-(y/h)^2)...

The main water enters a house on the first floor. the line has a gauge pressure of 1.9x10^5Pa a) A faucet on the second floor 6.50 meters above the first floor is turned off. what is the gauge pressure of this faucet? b)how high could a faucet be before no water would flow from it even if the...

Can please anyone solve the following question in details... A cylindrical object of outer diameter 10 cm height 20 cm and density 8000 kg/m3 is supported by a vertical spring and is half dipped in water. Spring constant is 500N/m. (a) Find the elongation in the spring in equilibrium...

Hi, I am experiencing a little bit of trouble grasping the concept of vector fields in fluid mechanics: If the vector V = u i + v j + w k, where i,j,k are unit vectors in the x,y,z directions, then how can u,v,w be functions of x,y,z,t? I.e. if say v is in the y direction, then how can it...

Hi guys this is my first ever homework post on here so be nice please :D. 1. I have attached an attempt on paint to give you a very rough idea of the very simple heat exchanger. The pipes are cooled by the air and it is a good few metres above the ground. For simplicities sakes let's say, for...

Homework Statement #1 If you hold a block of lead and an identical size block of Styrofoam under water, the buoyant force will a) be greater on the lead block. b) be greater on the Styrofoam block. c) be the same on both blocks. d) depend on the depth that each block is held. #2 Salt...

Hi all, Am reading a few papers for a Uni case study about structures in Turbulent Boundary Layers over a Flat Plate (water), particularly low-speed streaks. I'm confused over what mechanism causes the span wise variations in velocity that seems to cause low speed streaks. Would...

Hello, I'm new to the forum. Does anyone have any suggestions for doing well on Fluid Mechanics? I got a 34 on my previous test (class average was a 35..). Any help would be appreciated. Ideally, I would love to find something like mech movies for mechanics of materials. My biggest...

Following this example, http://www.creatis.insa-lyon.fr/~dsarrut/bib/others/phys/www.jwave.vt.edu/crcd/batra/lectures/esmmse5984/node53.html I know you can solve for v by integrating the equations along with boundary conditions. How would you solve a problem where you have another...

Homework Statement Steady, laminar flow of an incompressible Newtonian fluid with constant physical properties. The area of interest in the problem is in the entrance region between two wise, horizontal parallel plates separated by distance 2B. z is in the direction of flow and x is the...

Is it usual to customise experiments in fluid dynamics and to what extent? I understand that lasers and imaging tools will be fairly untouchable by a fluid dynamicist, although does an experimental role require any 'tampering/customising of general system equipment i.e. rewiring/handy work...

Homework Statement A tube of uniform cross-section A is bent to form a circular arc of radius R, forming three quarters of a circle. A liquid of density \rho is forced through the tube with a linear speed v. Find the net force exerted by the liquid on the tube. 2. The attempt at a solution...

Homework Statement http://i50.tinypic.com/2m2tbaq.pngHomework Equations The Attempt at a Solution I suppose i have to apply the Bernoulli's equation here but i don't even have the slightest idea on how to apply it here. I am a dumb at fluid mechanics, any help would be appreciated.

I am studying plasma physics. While treating the plasma as a fluid, we replace the generla time derivative of velocity of any particle by the convective derivative. I would like to know the reason and also what is the frame of reference when we work with fluid dynamics.

If I had water at 180 degrees and dropped the temperature to 160 degrees over a heat exchanger, would I have the same BTU output as if I had water at 100 degrees and dropped the temp to 80 degrees? Delta T is 20 degrees for both situations. I know if we were talking about Ke related to mass and...

I'm interested in making a larger-scale French Press (VIDEO, go to :30) It has a mesh-screening filter that keeps the coffee grounds contained when you push down. I'm theoretically using a large bucket, like those 5gal buckets at Home Depot, with the dimensions shown below. And...

From some of the questions I'm encountering my text, it seems like the writers are implying that there always needs to be a difference in pressure for a fluid to accelerate (by this I mean a difference between the Pi and Pf values on either side of Bernoulli's equation). But is this really true...

Hello, I posted on college confidential and they advised me to come here. So here's my questions ! I'm currently a French student in fifth year of higher education (physics/engineering) and I'd like to do an internship in a US lab for 3 months. I currently have some opportunities : -...

Will anyone give me the derivations for continuty equation of fluid and euler's equation of fluid motion .