Fluids Definition and 522 Threads

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...

Hi PF! Can anyone help me understand the relationship between streamlines and pressure in an inviscid/incompressible flow? I know a streamline is everywhere parallel to flow. Is it ever possible for streamlines to cross each other? If you have a recommended reading please let me know, or if you...

If you increase surface tension, the molecules at the surface are more strongly pulled into the center of mass due to the stronger attractive molecular forces. -Why is it that when surface tension increases in a liquid, its surface decreases in area, but its volume does NOT change? (Volume...

Homework Statement It's not a homework exercise, it's more of a conceptual question to help my understanding of the subject. Imagine that you have a glass of height H filled with a fluid with density ro and viscosity eta. There is a hole somewhere on a side of the glass, at a height h relative...

1. Problem Statement: For the regular solution model, develop the equations for the compositions of the coexisting phases in a binary system and plot the phase boundary as a function of χ/RT.2. This question stems from Sandler's Introduction to Applied Statistical Thermodynamics. The Attempt...

Homework Statement Please see attached file for problem statement Homework Equations ΣM = Min - Mout = 0 The Attempt at a Solution I have tried using the equation of conservation of momentum on this problem but I'm getting stuck at how the viscous force of the liquid is playing a role in this...

Homework Statement I am studying for an upcoming exam and stumbled upon a website with a bunch of practice problems. I would typically state the question but this one is so long and requires a picture so here is the hyperlink to it: http://web.mit.edu/2.25/www/5_10/5_10.html Homework Equations...

Hi All, When explaining Pascal´s Principle I had some bad time related to its application in compressible fluids. Correlation functions (forces in two points separated in space at the same time) came to my mind but at the end the doubt persists. Is Pascal´s Principle valid for compressible...

I don't typically do this, but attached is a figure with a problem statement. This is not homework because I have already solved it! My question is a subtle one. Please see the attachments, one is the question and the other is my solution. I know my solution is correct, but at the end of...

Homework Statement Some underwater fish use a jet to move forward. The body expands with water and contracts, expelling water and thus propelling forward. For these purposes, assume that a submerged fish experiences a friction drag proportional to its surface area ##A_s## and proportional to...

How fluids would act around the circumference of a space centrifugal, where the habitable zones are. Given that we have a radial gradient of Artificial Gravity , plus Coriolis, inertia, frictions etc. Id expect some change. Will add a list of questions but this more like an open discussion...

Hello, I am trying to analyze an injector and having trouble coming up with the final equation for the calculation. The apparatus can be seen below. Assuming we know the inlet flow rate and pressure (A) from the pump/fan and the pipe geometry. The pressure out of the outlet of the nozzle is...

Homework Statement [/B] A simplified schematic of the rain drainage system for a barn is shown in the figure. Rain falling on the slanted roof runs off into gutters around the roof edge; it then drains through several downspouts (only one is shown) into a main drainage pipe M below the...

In Woodhouse's 'General Relativity' he finds an expression for the energy-momentum tensor of an isotropic fluid. If W^a is the rest-velocity of the fluid and \rho is the rest density then the tensor can be written as T^{ab} = \rho W^aW^b - p(g^{ab} -W^aW^b) for a scalar field p. The...

Technically, this isn't a question concerning supercritical fluids. It's more about converting thermal energy into velocity by playing "keep-away" with molecules that want to go supercritical. The idea is simple. In an fully contained system, we can more or less say volume is static...

Homework Statement Find height (h) of the water level which can result in failure of dam by tipping it over due to water pressure at U/S of dam. Also draw the free body diagram. Density of water to be = 1000 kg/m^3 and its specific weight=62.4 lb/ft^3 Hints: The specific weight of concrete is...

Homework Statement This is a basic cosmology problem. The Friedmann equations are ##\Big( \frac{\dot{a}}{a}\Big)^{2}+\frac{k}{a^{2}}=\frac{8\pi}{3m_{Pl}^{2}}\rho## and ##\Big( \frac{\ddot{a}}{a} \Big) = - \frac{4\pi}{3m_{Pl}^{2}}(\rho + 3p)##. Using the density parameter ##\Omega \equiv...

I am studying an inviscid fluid. I am trying to characterise the fluid. Does it make sense to call it Newtonian or should I avoid this designation? What I mean is - if there are no viscous stresses then does it make sense to characterise it's response to viscous stresses? (That box that doesn't...

Homework Statement I'm having a little trouble understanding how to derive the hydrostatic equations for fluid mechanics! My professor showed the derivation with respect to y in class, and it kind of made sense to me. Now I'm trying to see if I can derive the equation with respect to z and x...

As part of a racing community, there is a discussion going on that talks about compressibility of brake fluid. the Street car versions have a value of 6.5E-05 and the racing stuff is 4.5E-05 both at a pressure of near 5000psi. there is talk about the difference of the racing fluids which...

I'm a Mechanical Engineering student at the 4th semester, and I've been thinking about what specializations I should pursue after I get my bachelor's degree. I've always find mechatronics (control and automation) to be quite fun. I've developed some projects using Arduino and studied a little...

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...

Imagine a fish in a tank that is completely filled with water and closed on all sides. Can this fish swim? Since water is extermely difficult to compress, when the fish moves its fin to propel itself forward, the water can't move anywhere, so the fish should not be able to move right? Then I...

Hi, looking for help understanding the concept of SCF's. I understand that SCF'S are indistinguishable in their gas and liquid phases, and that they show properties of both. My question is, whose properties would they show in the event of a vessel failure? For example, if you took a 100 l...

can you help me with this, please?

Homework Statement Problem is as shown in the picture. The answer is meant to be a 4.59mm. Homework Equations Tau=mu(du/dy)The Attempt at a Solution Force (tau) acting on plate from both fluids is equal, as is velocity (du). mu1 (du/dy1) = mu2 (du/dy2) mu1/dy1 = mu2/dy2 (mu2/mu1) *y1 = y2...

Hello, We all know that, in Commercial aviation, we use Hyjet (SKydrol or 500B4). and in military we use MIL-H-83282 (red oil). what are the main reasons? MIL-H-83282 has a synthetic hydro carbon base and contains additives to provide the required viscosity and anti wear characteristics, which...

Homework Statement Two identical balls A and B are dropped from rest into a tall column of viscous liquid. Ball A is dropped from the surface of the liquid while ball B is dropped from a small height ##h## above the liquid. Let ##E_A## and ##E_B## be the loss in mechanical energy of bal A and B...

I first wanted to ask a very specific question: There is something called the Brunt-Vaisala frequency. It describes the frequency of oscillation in a fluid with a density gradient. Because if a parcel of fluid is pushed up or down from its stable state it will oscillate around it. What i don't...

Hi PF! So my book has boiled the problem down to $$\psi(r,\theta) = c_1 \ln \frac{r}{a}+\sum_{n=1}^\infty A_n\left(r^n-\frac{a^{2n}}{r^n}\right)\sin n\theta$$ subject to ##\psi \approx Ur\sin\theta## as ##r## get big. The book then writes $$\psi(r,\theta) = c_1 \ln...

Hi, I would like to ask that whether or not ## non-slip condition## is valid for inviscid fluids. We know that inviscid fluids there is no friciton. If there is no friction in the inner surface of pipe (I do not name its technical name) so it seems that there cannot be the non-slip condition...

Homework Statement See attached image: Homework Equations p/ρg + V^2/2g + z = constant head loss (major) = f * l/D * V^2/2gThe Attempt at a Solution To use the energy equation while incorporating head loss, I need to determine the velocity in each section of pipe. The problem is I don't know...

Homework Statement An open cylindrical tank of acid rests at the edge of a table 2.20\cdot 10^0\ m above the floor of the chemistry lab. If this tank springs a small hole in the side at its base, how far from the foot of the table will the acid hit the floor if the acid in the tank is...

I am intrigued by the diversity of Non-Newtonian fluids and need to ask a question. Can anyone provide me with a breakdown of what goes on at the quantum level as the Non-Newtonian fluid bounces up and down on top of the speaker in the video I have embedded. What I would like to know is...

I was given the task to create a hull which must be propelled by human and solar power; I have found it difficult to obtain existing hull designs with their respective coefficient of total resistance so I am looking for a way to calculate the total hull resistance for a hull of my own. I...

Homework Statement A layer of oil that has a density of 930kg/m^3 is floating on the surface of water in a container if a wooden cube with a length of 4 cm becomes submerged where it's lower half is in water and it's upper half is in oil the cube's density is 960kg/m^3 find A) the buoyancy...

A stream of water at 300 Deg K flowing into a mixture at a velocity of 5m/s. Another stream of water at 400 Deg K is flowing in at 8 m/s.How to calculate the final velocity and temperature of the fluid after mixing? Please find the attached image? If it requires any c/s dimensions please assume..

How does one setup the stress tensor for a non-Newtonian fluid? I know that for any fluid the normals should be the pressure and for a power law fluid the shear stress in the direction of flow is related by K(du/dy)^n. Does this mean that all other components are 0 for a symmetric pipe or...

Is the Moody Chart valid for non-Newtonian fluids?

Homework Statement A circular cylindrical barrel is half full with oil. If the diameter of the base is 8.0 m, find the net force against each end if ρo = 800 kg/m3. The cylinder is on its side. Homework Equations F=P*A P=ρgdy The Attempt at a Solution P = ρo*g*h, where h is the radius which...

Hi All, What is the maximum number of layers of immiscible fluids in nature. Is seems intuitive to me that this limit exists. for the sake of definiteness, let' s consider usual laboratory"s condition of temperature and pressure. Best wishes, DaTario

Homework Statement A block floating on water contained in a vessel is pushed inside until it touches the bottom of the vessel and then released. Will the block come back? Homework EquationsThe Attempt at a Solution [/B] Bouyant force acts because the pressure on the bottom of the block is...

Homework Statement if an object is in equilibrium at the interface of 2 fluids in an open tank, why do both provide upthrust? Homework Equations P=P' +dgh The Attempt at a Solution The upper fluid is not in contact with the lower part of the object, so why would the fluid provide an upward...

I am trying to come up with a mathematical model so that, when the displacement of the plunger of a syringe is know, I can calculate the amount of a specific liquid in the barrel. Or the relationship between the speed of the plunger and flow rate at the tip of the needle (Again assuming that the...

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

I was asked to explain how different factors affect surface tension. I can understand how temperature plays a role. 1) Contamination: Increase in contamination decreases surface tension. I tried thinking about it.I thought maybe the particles that contaminate the fluid get in the way and...

Homework Statement What should be the pressure inside a small air bubble of 0.1,, radius,situated just below the surface? st of water=7.2 *10-2 and atmospheric pressure=1.013*105. Homework EquationsThe Attempt at a Solution I am of the understanding that the pressure inside the...

Hello! I understand what specific heats are and how to derive them. I just feel that I'm missing a little something in the methodology. Consider the 1st law of thermodynamics and the definition of enthalpy: 1) dU = δQ -δW = δQ - PdV 2) H = Q - VP For the derivation of CV, dV = 0 and the...

Great for those interested in animations

Homework Statement The gauge pressure at the inlet of a horizontal venturi meter is 40kPa. The vacuum at the throat is 38 mm mercury. If a differential U-tube manometer containing mercury is the U-tube and the oil in the connecting tubes is connected to the venturi, what will the difference in...