Introduction to
Fluid Mechanics
Concept of a Fluid
How to distinguish fluid from solid?
Fluid is a substance that deforms continuously
under the application of a shear stress (tangential
force per surface area). This implies that fluids
at rest cannot re
MECH2008 (2011 2012) Mid-Term Test
A long solid circular cylinder of radius Rs rotates about its centerline with a constant angular velocity .
The cylinder is surrounded by an annular layer of Fluid I, and on the outside is an infinite mass of Fluid II.
T
Name:
U. No.
MECH2008 Mid-Term Test
November 9, 2010
4:00 5:55 pm
No materials other than the handouts and class notes are permitted.
All symbols have their usual meanings (e.g., V for velocity, p for pressure, for dynamic
viscosity, etc.)
Section A (10 m
Name:
MECH2008 (2009-2010) Mid-Term Test
(OPEN NOTES)
U. No.:
November 12, 2009 5:00-5:55pm
Instructions
Write your answers in the space provided, and hand in this sheet when you have finished the
problem. Attempt all parts.
A two-dimensional flow field h
Name:
MECH2008 (2008-2009) Mid-Term Test
Encircle one below
(OPEN NOTES)
U. No.:
(ME/BSE/MedE/Ex)
November 7, 2008 4:00-5:55pm
Instructions
Write your answers in the space provided, and hand in this sheet when you have finished the
problems. Attempt both
Name:
U. No.
MECH2008 Mid-Term Test
November 9, 2007
2:00 3:55 pm
No materials other than the handouts and class notes are permitted.
Write your answers in the blank space provided. Do your rough work elsewhere.
Question 1
Consider the following two strea
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MECH2008 Mid-Term Test
November 17, 2006
2:00 3:55 pm
No materials other than the handouts and class notes are permitted.
All symbols have their usual meanings (e.g., V for pressure, p for pressure, etc.)
Section A (10 marks)
Encircle the let
Potential Flow
Inviscid Flow
Flow of an ideal fluid with zero viscosity ( = 0) would be
inviscid exactly.
In practice, flow is approximately inviscid when the effects of
shear stresses on the motion are small as compared to other
influences. One guiding
Open-Channel Flow
Introduction
Open-channel flow is important for design and planning of
river control, inland navigation, surface drainage, irrigation,
water supply and urban sanitation.
An open channel is a conduit in which the liquid flows with a
fre
(V) OPEN-CHANNEL FLOW (Chapter 10)
A. Introduction
Studies of open channel flow are important for design and planning of river control,
inland navigation, surface drainage, irrigation, water supply and urban sanitation.
An open channel is a conduit in w
(IV) FLOW PAST A BODY AND BOUNDARY LAYER THEORY
(Chapter 9)
A. Introduction (Section 9.1.2)
In 1904, Prandtl developed the concept of the boundary layer, which provides an
important link between ideal-fluid flow (inviscid irrotational flow) and real-fluid
(III) INVISCID AND POTENTIAL FLOWS (Sections 6.4-6.6)
Analysis can be considerably simplified if the flow under consideration can be regarded as
INVISCID and IRROTATIONAL.
A. Inviscid (Nonviscous) Flow (Section 6.4)
Flow of an ideal fluid with zero visco
(II) SIMPLE (EXACTLY OR NEARLY ONE-DIMENSIONAL)
VISCOUS FLOW (Section 6.9)
A. Mathematical Formulation for a Fluid Dynamics Problem
Assumptions:
constant fluid properties (density , viscosity )
Newtonian fluid (linear, isotropic and purely viscous mater
Department of Mechanical Engineering
The University of Hong Kong
Mechanics of Fluids MECH2008 (2012 2013)
Lecturer:
Prof. C.O. Ng (office: HW7-1; phone: 28592622; email: [email protected])
Required Texts: 1) Fundamentals of Fluid Mechanics 6th Ed., B.R. Munson,
Elementary Analysis of
Fluids in Motion
Basic Variables for Fluid Motion
Velocity = distance/time.
Velocity is the most important kinematic variable of
a flow field. It is a vector function of space and time.
Pressure = isotropic (i.e., independent of d
Fluid Statics
Pressure
Pressure always acts inward normal to any
surface.
Pressure is a normal stress, and hence has
dimensions of force per unit area, or [ML-1T-2].
In SI units, pressure is expressed as "pascals"
(Pa) or N/m2.
Pressure is formally def
(IV) FLUIDS IN MOTION
Fluid motions manifest themselves in many different ways. Some can be described very easily, while
others require a thorough understanding of physical laws. In engineering applications, it is important
to describe the fluid motions a
Department of Mechanical Engineering
The University of Hong Kong
Foundations of Engineering Mechanics
ENGG1010 (2011 2012)
"Mechanics of Fluids"
Lecturer:
Dr. C.O. Ng (office: HW7-1; phone: 28592622; email: [email protected])
Required Text: Fundamentals of Flui
Differential Analysis
of Fluid Flow
Cartesian Coordinates
Position vector
x = ( x, y, z ) = ( x1 , x2 , x3 ) = xi ( i = 1, 2,3)
Velocity
V = (u , v, w) = (u1 , u2 , u3 ) = ui ( i = 1, 2,3)
Spatial gradient operator = , , =
,
,
=
x y z x1 x2 x3 xi
e.g.
Viscous Flow Past a Body
and Boundary Layer
Shortcomings of Potential Flow
For high-Reynolds-number flow past a body,
UL
inertia
Re =
1
=
viscous force
flow is essentially non-viscous, hence irrotational if vorticity free
potential flow to be governed b