Basic Fluid Mechanics: Course Overview

• Course-Workshop NRC: 178392
• Mechanics of Basic Fluids taught by Professor Edgar Mauricio Santos Ventura

Evaluation of Basic Fluid Mechanics

• Departmental Exams accounts for 30%
• Partial Exams counts for 20%
• Practices equals 15%
• Activities and Tasks equals 15%
• Final Project equals 20%

Unit of Learning Identification

• Learning Unit Name: Basic Fluid Mechanics
• UA Code: IH115
• UA Type: Course-Workshop
• Credits: 8
• Training Area: BPO
• Semester Hours: 4 hours per week
• Theory Hours: 40 hours per semester
• Practice Hours: 40 hours per semester
• Total Hours: 80
• Department: Basic and Applied Sciences
• Academy: Mechanical Engineering

Presentation

• Fluids are influential in life, ecosystems, and most technologies that harness energy resources
• Working fluids in energy processes require understanding of governing principles for storage, conditioning, and transport

Learning

• Knowledge of physical principles and laws governing fluid behavior
• Ability to analyze fluid behavior at rest under varying conditions
• Ability to analyze ideal stationary flow
• Ability to Interpret hydrodynamic behavior

Generic competence

• Commitment, promise fulfillment, service attitude, collaboration, and honesty are important values

Professional Competence

• Ability to understand and analyze fluid behavior in static and dynamic conditions, accounting for energy considerations

Requisite student knowledge

• Familiarity with the physical variables in fluid studies
• Understanding of classical mechanics on Earth's surface
• Comprehension of statics, kinematics, and dynamics applicable to bodies at rest or in motion on Earth

Fluid Definition, Matter States

• Fluid: continuous medium with weak molecular attraction
• Fluid: particle collection held by weak cohesive forces
• Matter States: Bose-Einstein condensate, Solid, Liquid, Gas, Plasma

State Changes

• Fusion/Evaporation: heat is added
• Solidification/Condensation: heat is removed

Liquid Properties

• Cohesion: intermolecular attraction between like molecules
• Adhesion: attraction between unlike molecules
• Convex meniscus happens with Mercury
• Concave meniscus happens with water
• Fluids exist as liquids or gases, solids have diverse classifications.

Solids Classifications

• Crystalline Solids: ordered, anisotropic, with a defined melting point
• Amorphous Solids: unordered, isotropic, without a defined melting point

Types of Solid

• Ionic solids have cations and anions, electrostatic forces, high melting points, and are hard insulators (e.g., NaCl, LiF)
• Covalent solids have atoms, covalent bonds, hardness, high melting points, and are insulators (e.g., Diamond, SiC)
• Metallic solids have atoms, metallic bonds, are conductors with electrons (e.g., Na, Fe)
• Molecular solids have molecules/atoms, covalent bonds, Van der Waals forces, low melting points, and are insulators (e.g., Argon, CH4, CO2)
• Molecular Hydrogen solids have molecules, covalent bonds, hydrogen bonds, low melting points, and are insulators (e.g., ice, HF)

Pressure Definition

• Pressure is the amount of force exerted on a unit area of a substance or surface
• P = F/A = mg/A = pVg/A = pAhg/A = phg

Pressure Calculation

• Given density (p), gravity (g), and height (h), fluid pressure can be calculated
• P = pgh

International System of Units (SI)

• Length (L): meters (m) ≈ feet (ft)
• Mass (m): kilograms (kg) ≈ pound-mass (lbm)
• Time (t): seconds (s)
• Temperature (T): Kelvin (K) ≈ Rankine (R)
• Electric Current (CE): Amperes (A)
• Luminous Intensity (I): Candela (Cd)
• Substance Amount (Cm): moles (mol)
• Derived units include volume, force, energy, and work

Compressibility

• Describes volume change under pressure, quantified by the volumetric elasticity modulus (E)
• E = -ΔP / (ΔV/V)

Volumetric Modulus Values

• Ethyl Alcohol: 896 MPa
• Benzene: 1062 MPa
• Machine Oil: 1303 MPa
• Water: 2179 MPa
• Glycerin: 4509 MPa
• Mercury: 24750 MPa

Thermal Expansion

• Most materials expand when heated and contract when cooled, but water and rubber behave oppositely
• Gases expand more significantly than liquids, and liquids more than solids

Thermal Expansion Types

• Linear expansion
• Superficial expansion
• Volumetric expansion

Thermal Calculation

• Used to calculate the linear expansion coefficient: α = (Lf - Lo) / [Lo(Tf - To)]
  • α = linear expansion coefficient in °C-1
  • Lf = final length in meters (m)
  • Lo = initial length in meters (m)
  • Tf = final temperature in Celsius (°C)
  • To = initial temperature in Celsius (°C)
• Used to calculate the superficial expansion : Af = Ao[1 + γ(Tf – To)]
  • γ = superficial expansion coefficient in °C-1
  • Af = final area in (m²)
  • Ao = initial area in (m²)
  • Tf = final temperature in Celsius (°C)
  • To = initial temperature in Celsius (°C)
• Used to calculate the volumetric expansion:Vf = Vo[1 + β(Tf – To)]
  • β = volumetric expansion coefficient in °C-1
  • Vf = final volume in (m³)
  • Vo = initial volume in (m³)
  • Tf = final temperature in Celsius (°C)
  • To = initial temperature in Celsius (°C)

Vapor Pressure, Definition

• Vapor pressure describes the pressure exerted by a gas or vapor in equilibrium with its liquid phase in a closed system at a given temperature
• solids exhibit this phenomenon as well through sublimation
• Defines a substance's volatility, or ability to transition from solid/liquid to gas

Raoults Law

• Formula to calculate the vapor pressure of a component in solution
• Pv = yP
  • Pv = vapor pressure of the component
  • y = mole fraction in the vapor phase
  • P = total system pressure

Cavitation Definition

• Cavitation is a two-stage physical process where a liquid transitions to a gaseous state and then back to a liquid state

Cavitation Stages

• Stage one: Liquid changes to a gaseous state
• Stage two: Gaseous becomes liquid

Surface Tension, Definition

• Surface tension arises from an imbalance of intermolecular forces/cohesive forces at a liquid’s surface
• Surface tension is the energy needed to increase a liquid's surface per unit area

Capillarity

• Capillarity involves a fluid's ability to rise or fall in a capillary tube due to its surface tension and is based on fluid cohesive forces
• Liquids rise in tubes when intermolecular/cohesive forces are less than the liquid's adhesion to the tube.
• Water's capillarity aids its ascent in plants against gravity given this phenomeon.

Jurin's Law

• Jurin's Law defines the height a liquid reaches through capillary action when the column's weight balances against the ascension force
• Equation for column height (m): h = (2σcosθ) / (ρgr) where:
  • σ (N/m) is interfacial surface tension
  • θ is the contact angle
  • ρ (kg/m³) is the liquid density
  • g (m/s²) is the acceleration due to gravity
  • r (m) is the tube radius