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Fluid Mechanics

Fluid dynamics is the study of fluid flow. It has two subdisiciplines, aerodynamics and hydrodynamics. Fluid dynamics is used in a wide range of applications. One can calculate the forces on aircrafts, determine flow through pipes or predict weather patterns by using fluid dynamics. Some principles from fluid dynamics are even used in traffic engineering. Fluid dynamics is cross disciplinary and studied in a wide variety of ways.
The foundation of fluid dynamics is the conservation laws. These laws are based off classical mechanics but modified in quantum mechanics and general relativity. From these principles the Reynolds Transport Theorem was created. To model more complex equations of Newtonian fluids, physicists use the Navier-Stokes equations which model the behavior of fluids in a series of differential equations. Computational physics is often used in order to solve these complex problems in which stress and velocity are dependent on linearity.


Definitions
Compressible Fluid – The density changes with a change in pressure or temperature.
Incompressible Fluid – The density change is negligible with a change in pressure or temperature.
Viscous Flow – The fluid friction does not have significant effects on the fluid motion. Viscous flow indicated the Reynolds number is low.
Inviscid Flow – The fluid Friction has significant effects on fluid motion. The Reynolds number is high.
Steady Flow – The fluid properties throughout the system do not change.
Unsteady Flow – The fluid properties change through the system.
Laminar Flow – The fluid flow is in parallel layers with no disruptions. The Reynolds number is less than one.
Turbulent Flow – There is recirculation and apparent randomness of flow. The Reynolds number is greater than one.
Newtonian Fluid – The viscous stresses arise from the flow at every point. These stresses are proportional to the local strain rate over time.
Non-Newtonian Fluid – The viscosity of the fluid is dependent on shear rate.

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Categories within Fluid Mechanics

Aerodynamics

Postings: 14

The study of air and other gases in motion.

The Physics of Pressure Washers

A popular brand of pressure washer claims to deliver 330 litres per hour of water at a pressure of 80 bar, drawing 1,400 W of electrical power in the process. Pressure washers of this type are made up of an electric motor that drives a small compressor to pressurize water fed into it through a garden hose. a.Show that the amoun

Fluid Mechanics: Airplane Wing Design

One of the most important applications of fluid dynamics is in the design of airplane wings. In this SLP, we'll introduce some basic terminology and take a quick look at the relationship between angle of attack, airspeed, and lift. Go to the NASA GRC (2010) link on the Background page, which is a simulation called FoilSimII

Fluid Mechanics: Static and Dynamic Pressures

1. A laboratory receives a sample of a metallic alloy composed of aluminum and magnesium. The sample is a solid cylinder with a diameter of 2 cm and a length of 5 cm. Its mass is 15.70 g. What is its density? What is its specific gravity? 2. A boat has a dry weight of 3500 lbs. How many liters of water does it displace?

Fluid Dynamics Pressure Studies: Pressurized Tank Underwater

Please refer to two attachments for full details including diagram. Phase 1 Valve A, B, and E are closed. Tank A and B are separated and each sealed from the atmosphere. Tank A initially has 3' of air @ 40 psi Tank C and Tank B initially contain air @ 32.476 psi Pipe K is 12" id; initial air pressure is 32.476 p

Better Formula for Fluid Mechanics Problem

An open channel having a rectangular cross section is laid so that the rate of grade is 0.00048. The width of the channel is 10.00 ft, and the value of n in Kutter's formula may be taken as 0.011. When the depth of the water in the channel is 4.00 ft, the velocity computed by the Chezy formula is?

Condition for Irrotationality of a 2-d Ideal Fluid Flow

See the attached file. Working from first principles show that the condition for irrotationality of a two-dimensional ideal fluid flow is given by: delta(u)/delta(y) = delta(v)/delta(x) Hence, define in mathematical terms the velocity potential psi, and show that potential lines of constant psi are perpendicular to st

Magnitude and Direction of Shearing Stress

A layer of water flows down an inclined fixed surface with the velocity profile shown in the figure. Determine the magnitude and direction of the shearing stress that the water exerts on the fixed surface for U = 3 m/s and h = 0.1 m. Please refer to the attached figure for a visual representation.

Fluid Mechanics, Moment of Inertia

A symmetrical trapezoidal plate has the following dimensions: the widths of the parallel sides are, respectively, 2.50 ft and 4.50 ft; the perpendicular distance between those sides is 1.50 ft. the plate is submerged in a liquid in a vertical position with the parallel sides horizontal and the shorter parallel side at the top an

Schwarzschild Radius

Suppose two black holes meet and coalesce into one larger black hole. If they have the same mass M and Schwarzschild radius R, a) Express the new single black hole's Schwarzschild radius as a multiple of R. b) Express the average density of the new single black hole in terms of the average density (rho) of each of the or

Blood flow in an artery

The blood speed in a normal segment of a horizontal artery is 0.106 m/s. An abnormal segment of the artery is narrowed down by an arteriosclerotic plaque to 1/5 of its normal cross-sectional area. What is the difference in blood pressure between the normal and constricted segments of the artery?

A technician is using a laser which is classed '3B'

6. A technician is using a laser which is classed '3B (Restricted)' within the guidelines of Australian Standard AS2211.1-1997 a) What is the maximum radiant exposure the technician could receive in the 0.20s it takes to blink? b) If the MPE for the technician is 6mJm-2, what optical density would be appropriate for the gla

Fluid Dynamics and Drag Forces

We would like to know the nature of the drag forces experienced by a sphere as it passes through a fluid. The sphere has a low speed. Therefore, the drag force is highly dependent on the viscosity of the fluid. The fluid density is to be neglected. a) Use dimensional analysis to develop a model for drag force: F (MLT^-2) as a

Mechanical and Materials Engineering - Fluid Mechanics

Attached is a diagram of an oil storage drum that is open to the atmosphere at the top. Some water was accidentally pumped into the tank and settled to the bottom as shown in the picture. Find the depth of the water h2 if the pressure gage at the bottom reads 158kPa(gage). The total depth hT= 18.0m.

Find the viscosity of the oil.

In a falling-ball viscometer, a steel ball 1.6mm in diameter is allowed to fall freely in a heavy fuel oil having a specific gravity of 0.94. Steel weighs 77kN/m^3. If the ball is observed to fall 250mm in 10.4s, find the viscosity of the oil.

Apparent Weight and Actual Weight

Please help with the given problem: ** Please see the attached file for the figure depicting the described problem ** You must compute the ratio of the actual weight of the crown (W_actual) and the apparent weight of the crown when it is submerged in water (W_apparent). See whether you can follow in Archimedes' footsteps. Th

Mechanical Engineering Design

1 The carbon dioxide in a nuclear reactor is maintained at 40 bar (gauge) and 70 deg C. Estimate its density, specific weight and relative density. 2 A water-filled manometer indicates a pressure differential of 2100 N/m2. What is the difference in elevation of the vertical limbs?

Density and Radius of a Fuel Line

Fuel line in car fuel is going at a certain rate a fuel has certain density and certain radius for the fuel line. Find the speed at which the fuel is moving through fuel line given fuel transfer rate, density of fluid, and radius of fuel line.

Enthalpy calculation

Rotary air compressor problem 1a/ a rotary air compressor increases the absolute pressure of the air from 100 kNm-2 to 230 kNmm-2 and the specific volume of the air is reduced from 0.7m3 kg-1 to 0.46 m3 kg-1. If the internal energy of the air is increased by 40 kj kg-1 find the change in enthalpy of 8 kg of air. b/ If at

Oscillator response function

Obtain the response of a linear oscillator to a step function and to an impulse function (in the limit t goes to infinity) for over-damped oscillator. Sketch the response functions.

Proposal for airline mechanics

Library Assignment Many staff in the airline service end feel they are overtaxed while others seem to have little to do. Divide up key airline staffing roles among your small group, choosing one role per person, I chose the mechanics. (Preventive Maintenance) Individual Portion The individual portion of this project is

Problems on Fluid Dynamics

Two problems on fluid dynamics: Problem 1: Water flowing in a pipe with two sections with different cross section areas. To determine pressure, velocity and flow rates in the two sections. Problem 2: Water in a tank being siphoned off. To determine velocity, pressure, flow rate etc.. See the attached file.

Four problems on mechanics.

Please see attached file for full problem description. #16 A 58-kg skier is going down a slope oriented 35° above the horizontal. The area of each ski in contact with the snow is 0.13 m2? Determine the pressure that each ski exerts on the snow. #22 Measured along the surface of the water, a rectangular swimming pool has

Head-box issues in Pulp Mill : Theoretical Modelling Question

The process in question uses a centrifugal fan pump to convey a 1000 gallon per minute flow containing 2% finely ground wood pulp to a head box...which in turn is supposed to ocnvert turbulent flow to laminar flow and then deposit the water & pulp slurry on a high speed moving wire in order to form a wet fiber mat. However, t

Simple Fluid Mechanics: Liquid between two plates

You have a liquid sitting between 2 plates. A shear stress is applied to the top plate causing it to move. (the bottom plate is rigid) This fluid has a yield stress (ty) bellow which it will not move. Assume that the liquid, where in contact with the plate, moves at the same velocity as the plate. Also assume that the fluid h

Pressure at a point in a horizontal tube

Water is flowing in a horizontal tube. The pressure at a point is 0.01 m of Hg at which the velocity is 0.6 m/s. What is the pressure at a point where the velocity is 0.8 m/s ?