Fluid Definition and 1000 Threads

Homework Statement A conductor sphere of radius R without charge is floating half-submerged in a liquid with dielectric constant ##\epsilon_{liquid}=\epsilon## and density ##\rho_l##. The upper air can be considered to have a dielectric constant ##\epsilon_{air}=1##. Now an infinitesimal...

Hi all! I have started reading Fluid Mechanics at my own pace (no university study) and really I would like to grasp the ideas behind it. So I have Fluid Mechanics by Cengel - 4th edition. At page 45 the coefficient of compressibility or bulk modulus of elasticity (κ) is introduced. ##κ =...

Homework Statement [/B] Homework Equations ##P=\rho gh## The Attempt at a Solution So this is the first time I'm doing fluid mechanics, and I'm trying my best to understand it. This was the first question, and truth to be told, I'm not very confident. I know what gauge pressure is: the...

I'm trying to get a better handle on the actual physical phenomena underlying viscosity (for Newtonian fluids). Something I could word in the format of "this happens (and this and this), and so the fluid resists flow." What I've found online is that when gasses are at higher temperatures, they...

Hi. Pascal's law states that static pressure in a confined incompressible fluid without gravity is the same everywhere. Is this law derivable from more fundamental laws? Some thoughts: Is Pascal's law part of the definition of the liquid state? If the liquid operates between two hydraulic...

Homework Statement (I) An experiment to determine ceramic particle sizes showed that the rate of descent when suspended in a fluid ranged from 1.2 × 10–6 m s–1 to 5 × 10–6 m s–1. 
The density of the material was 3800 kg m–3 and the density and viscosity of the fluid at room temperature were...

Is measuring pressure for a compressible fluid system angle dependent?For a compressible fluid, Bernoulli's Law gives us a relation between two points along a closed system. More specifically it gives us the relation between two cross sections belonging to two distinct points in the closed...

What does it mean the word 'Jet' in fluid mechanics, special when it depends on the free surface?!

Homework Statement Water is supplied at 4.50 m3/s and 415 kPa (abs) to a hydraulic turbine through a 1.0-m inside diameter inlet pipe as indicated in the figure. The turbine discharge pipe has a 1.2-m inside diameter. The static pressure at section (2), 3 m below the turbine inlet, is 25 cm Hg...

Homework Statement A zeppelin of an ellipsoid shape (a=32m, b=c=a/3) iz filled with hydrogen. Pressure of the surrounding air is 100 000 Pa. Temperature of air and hydrogen is 20°C. The mass of an empty (not filled with hydrogen) zeppelin is 10 000 kg. What does the pressure of hydrogen inside...

I have a cylinder of some dimensions. I have a compressible liquid inside. Assuming a constant temperature, no atmosphere, no convection currents within, because it is in a cylinder, there will be no variations in density horizontally (the fluid will have time to settle). Now because there is...

The energy momentum tensor of a perfect relativistic fluid is given by $$T^{\mu\nu} = (\rho + p)u^\mu u^\nu + p g^{\mu\nu}$$ I don't understand why this is a tensor, i.e. why it transforms properly under coordinate changes. ##u^\mu u^\nu## and ##g^{\mu\nu}## are tensors, so for ##T^{\mu\nu}##...

Hi, I`m seeking for help in the following problem. A flat vertical board is traveling in water which is to be considered as ideal. One of its ends is in water, the other one is outside the water. Its velocity is v with respect to its normal. What is the velocity of the water stream directed up...

Assuming laminar viscous (meaning not frictionless) flow. Here is what I know about fluids flowing: You have a pressure difference between the two ends of the pipe. This causes a net force acting on the left side of the fluid in the pipe. Therefore, this incompressible fluid flows from left to...

So I've been discussing this problem with my plumber dad. I uploaded the picture. I'm wondering if the pressure would change in the red pipe since the diameter decreases to 4 cm. Assume the 1st 10 cm pipe is full with water. Question: If the home pressure is 517 kPa going through first pipe...

Dear All I am an undergraduate student studying in physics. I would probably get into research that needed fluid dynamics and CFD (computational fluid dynamics) skills. Previously I have not been taking a formal fluid dynamics course since there is none. I would like to pick up those skills by...

Homework Statement Find the flow rate of water. The fluid in the manometer is mercury. ##d_{1},d_{2}## are the diameters in the figure Homework Equations Bernoulli, continuity equations The Attempt at a Solution We know that ##p_{1}=p_{1Top}+\rho_{water}gh_{2}##...

Dear all, I have a headache and I need you help, with the following problem. I need to create excel sheet for the calculation (estimate) of the size of the orifice on the orifice plate that will produce a pressure reduction rate in pipeline at 0,5 bar per minute. It is not important to...

Homework Statement (In the attachment)There is two layers of liquids in the container .The density of the upper layer of the container, ##ρ_1=800kg/m^3## and the density of the bottom layer of the container ,##ρ_2=13600kg/m^3## .What is the pressure at the bottom of the container? Homework...

HI All, I have been out of education a long time and am now back at college. One of my modules is Fluid Dynamics and I am beginning to struggle with the basics and could really use your help. I have attached a snip from one of the example questions below given to me by my lecturer. For part...

Recently, on a conversation with PhD in Engineering, I came to know that if, instead of the whole wing, air/fluid flows over part of it, then that will cause great turbulence and swirl. When I asked him for reference, he said that it can be found in any book on Aerodynamics. But still today, I...

Homework Statement Homework Equations y1+P1/##\gamma##+##\alpha##v12/2g = y2+P2/##\gamma##+##\alpha##v22/2g + hL The Attempt at a Solution so it gives me pressure at p2 but not p1. I tried using Bernoulli's equation to find p1 i did plugged into energy equation above and got an answer but...

Consider the very standard pipe problem used to calculate the force required to hold a pipe with a bend that has some fluid flowing through it, as shown in the image. We use Newton's second law of motion to calculate the external force required. However, why is there pressure acting into the...

Suppose a fluid passes from having laminar flow, to having a turbulent flow (like when passing after an object). How do fluid speed and fluid density change after that?

Suppose you have a spherical cavity, with a flow of a fluid ( in particular water), entering it from one side. What will happen to this flow? Will it create turbulences? Will speed increase? Will eventual waves entering the cavity be reflected, so creating waves with bigger amplitude? Suppose...

Homework Statement Homework Equations The Attempt at a Solution [/B] My questions: 1. By resultant force, does that mean the force exerted on the side of the water + force exerted on side of the oil? Because I'd think that the force on the side of the water would be different than the...

Homework Statement A mechanical servo-mechanism comprising of a movable piston-cylinder within a vertical cylinder operates based on a venturi contraction in a horizontal 350mm diameter pipe that delivers a fluid of relative density 0.95. The upper end of the 100mm diameter vertical cylinder is...

I'm trying to think through a situation, and develop some confidence I've got it right. The situation is a apartment building, about 60'/20m high, with a courtyard in the middle about 60'/20m square. In the middle of the courtyard, is an low exhaust stack, about 8' high and around 8' square...

Homework Statement The figure below shows a metal object (2) hanging by a thin cord from a floating wooden block (1). The wood block has a SG of 0.3 and dimensions of 50mm x 50mm x 10mm. The metal part as a volume of 6600m^3. Find the mass of the metal part and the tension in the cord. Work in...

Homework Statement The points of interest are at point A and B, I want to calculate the pressures at that point. I am working in gage pressure so we can ignore atmospheric pressure. Homework Equations P = pgh P = sg x specific weight of water x height The Attempt at a Solution Attempting a...

Hi everyone, I have a real life fluids problem I am trying to solve theoretically. During a commissioning exercise we needed to discharge fuel into a 100L steel drum to test flow rates for a new re-fuelling skid. To minimise turbulent flow and static build up a drop pipe was used for the hose...

Homework Statement Shown in the figure attached. Circular duct with a diameter of 150 mm, strikes a cup and exits through a circumferential slot to the atmosphere. Mean velocity in the duct = 100 ms^-1 Air density = 1.1 kg/m^3 Dynamic viscosity of air = 19.05 x 10^-6 kgm^-1s^-1 (a) Determine...

Homework Statement At the start of a compression, a cylinder contains 0.04 m^2 of some ideal gas at a pressure of 100kPa and a temperature of 110 degrees. Compression takes place according to the law: P(V)^1.27 = constant The gas undergoes a two stage process: compression from 0.04 m^3 to...

Does ideal fluid have zero surface tension? What does zero surface tension signify?

How would you go about solving the following problems regarding a syringe full of water? First, find the magnitude of force required to be applied to a piston of an 85ml syringe with a 60mm diameter tube to drain the tube in 25 seconds through an outlet of 10mm diameter? Second, what would the...

During CFD modeling of a gas-solid flow, flow of solid was modeled as a perfect fluid using OpenFOAM. The density of the perfect fluid is calculated using the following equation as given in the documentation. ρ = P/RT + ρo , where ρo is the density at T = 0 kelvin, ρ is the density of the...

Complete question: Will flow ever reverse or stop if we increase resistance in this pipe scenario? There are 2 comunicating vessels. The highest vessel is coninuosly alimented with new water. Water in excess flows down on the sides. Water will try to reach the same height in both vessels, so...

Homework Statement Water flows over a dam as depicted below. Across section 1 and 2 we have a hydrostatic pressure distribution. Calculate the force on the dam. The Attempt at a Solution My question is regarding control volume. The solution manual has given us this: The two hydrostatic...

Homework Statement A sealed has a partition stuck down in water, creating two separate air pockets. The pressure at A is measured to 95 kPa (absolute) and the temperature is 20 C. Find the pressure at B. The Attempt at a Solution Why is the pressure at A not equal to B? Doing U-tube exercises...

Homework Statement I have a situation as illustrated by the image above, where the red box illustrates the CV. The pressure on the left side of CV is P1, while the pressure on the right side of CV is P2. Here I´ve directed the pressure forces acting inwards on CV. The problem arises with Fk. I...

Hello, in some exam questions I've looked at it is stated that the pressure distribution is hydrostatic, even though there is fluid motion. (In these cases the velocity has been constant over the section where the pressure is said to be hydrostatic). Is it really possible to assume that the...

Homework Statement I often have much trouble with fluid problems in general. I know what equations are involved but am confused on how to apply them to these problems. Homework Equations bern's equations P + pgh + 0.5pv^2 = constant P - pressure p = density v = velocity h= height from the...

The idea is that, if we take the rotating frame of the fluid-planet so that it is at rest, then the sum of gravity and the centrifugal force must be perpendicular to the surface. Take the planet to be rotating about the y-axis at a rate ω. By symmetry we only need to work in 2 dimensions. So...

Hi there, So I was doing the dishes this morning using a sink wand hat can toggle between different flow speeds. The way that I've always thought of this working is using the equation of continuity: Volume flow rate: = Area*velocity Pressing a button on the wand decreases the cross-sectional...

Homework Statement This should be pretty simple and I guess I am doing something stupid? ##T_{bv}=(p+\rho)U_bU_v-\rho g_{bv}## compute ##T^u_v##: ##T^0_0=\rho, T^i_i=-p##Homework Equations ##U^u=\delta^t_u## ##g_{uv}## is the FRW metric,in particular ##g_{tt}=1## ##g^{bu}T_{bv}=T^u_v## ##...

Hi, I am trying to code ultrasonic transducer radiation in water using angular spectrum of plane waves. I am having difficulties in the sampling and fft. If anybody has an idea about this can you please help me out? I can paste the code once i get some response. Thanks for your help!

Homework Statement Homework Equations because their is steady flow we only care about mass flow flux meaning m1vout - m2vout m = ##\rho##Av i know that m1 = m2 + m3 since there are no dimensions I am assuming that areas are the same everywhere, density does not change therefore velocities...

Hi, I have a vessel/chamber filled partially (25%) with silicon fluid (coefficient of thermal expansion is 0.00096 cm^3/cm^3/ °C) and the rest is filled with nitrogen gas at a certain pressure (P1) and temperature (T1). my question is, how to predict the final pressure (P2) If I increased the...

Suppose I have a wave tank partially filled with a shear thickening Newtonian fluid (Oobleck), on top of which sits a layer of water (separated by a thin membrane to prevent mixing) If I propagate a surface wave in the water layer how will it conduct itself at the Newtonian/Non Newtonian Fluid...

Hi PF, I'm trying to derive the Prandlt condition (not sure if it is Prandlt's work tough) for a fluid to separate from a surface in the boundary layer. The equation should be: ##\frac {\partial^2 v_x} {\partial y^2} = 0## which is quite "intuitive" to me. To derive it let's start from the...