ENGR 35200: Fundamentals of Thermal-Fluid Sciences - Key Vocabulary

Vocabulary flashcards covering core definitions, physical laws, system classifications, pressure types, dimensions, and thermodynamic processes from Chapter 1 of Thermal-Fluid Sciences.

Thermal-Fluid Sciences

The physical sciences that deal with energy and the transfer, transport, and conversion of energy, studied under the subcategories of thermodynamics, heat transfer, and fluid mechanics.

Thermodynamics

The science of energy, stemming from the Greek words therme (heat) and dynamis (power).

Conservation of Energy Principle

The principle stating that during an interaction, energy can change from one form to another, but the total amount of energy remains constant.

First Law of Thermodynamics

An expression of the conservation of energy principle asserting that energy is a thermodynamic property and can neither be created nor destroyed.

Second Law of Thermodynamics

A law asserting that energy has quality as well as quantity, and actual processes occur naturally in the direction of decreasing quality of energy.

Zeroth Law of Thermodynamics

A law stating that if two thermodynamic systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.

Third Law of Thermodynamics

A law stating that as temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

Classical Thermodynamics

A macroscopic approach to the study of thermodynamics that does not require knowledge of the behavior of individual particles.

Statistical Thermodynamics

A microscopic approach to thermodynamics based on the average behavior of large groups of individual particles.

Heat

The form of energy that is transferred between systems as a result of a temperature difference.

Heat Transfer

The science that deals with the determination of the rates of energy transfers and the variation of temperature.

Hydrodynamics

The study of the motion of fluids that can be approximated as incompressible, such as liquids and low-speed gases.

Hydraulics

A subcategory of hydrodynamics that deals specifically with liquid flows in pipes and open channels.

Gas Dynamics

The branch of fluid mechanics dealing with fluid flows that undergo significant density changes, such as high-speed gas flow through nozzles.

Aerodynamics

The study of gas flow (especially air) over bodies such as aircraft, rockets, and automobiles at high or low speeds.

Shear Stress

($\tau = \frac{F_t}{dA}$) is the force component tangent to a surface per unit area.

Normal stress

($\sigma = \frac{F_n}{dA}$) is the force component normal to a surface per unit area

System

A defined quantity of matter or a region of space chosen for study, separated from its surroundings by a real or imaginary boundary.

Boundary

Dictates what can be exchanged between the system and its surroundings

Open System

A system that freely exchanges both energy and matter with its surroundings.

Closed System

A system that exchanges only energy with its surroundings, not matter.

Isolated System

A system that exchanges neither energy nor matter with its surroundings.

Absolute Pressure

The actual pressure at a given position, measured relative to absolute vacuum ($P_{\text{abs}} = 0$).

Gage Pressure

The difference between actual pressure and local atmospheric pressure ($P_{\text{gage}} = P_{\text{abs}} - P_{\text{atm}}$).

Vacuum Pressure

Pressure measured when actual pressure is less than local atmospheric pressure (negative gage pressure: $P_{\text{vac}} = P_{\text{atm}} - P_{\text{abs}}$).

Boyle’s law

P1V1=P2V2

Charles law

P1/T1=P2/T2

Avogadro’s Law

V1/n1=V2/n2

Enthalpy ($H$)

A thermodynamic property representing the heat content of a system at constant pressure.

Primary Dimensions

Fundamental dimensions selected as basic physical quantities, including mass ($m$), length ($L$), time ($t$), and temperature ($T$).

Secondary Dimensions

Dimensions expressed in terms of primary dimensions, such as velocity ($V$), energy ($E$), and volume ($V$).

Specific Weight ($\gamma$)

The weight of a unit volume of a substance, defined mathematically as $\gamma = \rho g$.

Unity Conversion Ratio

A unitless ratio identically equal to $1$ formed by equivalent unit definitions (such as $\frac{1\,\text{N}}{1\,\text{kg}\cdot\text{m/s}^2} = 1$) used to convert units in engineering calculations.

Isobaric Process

A process occurring at constant pressure ($P = \text{constant}$).

Isochoric Process

A process occurring at constant volume ($V = \text{constant}$).

Isothermal Process

A process occurring at constant temperature ($T = \text{constant}$).

Adiabatic Process

A process during which there is no heat interaction between the system and its surroundings ($Q = 0$).

Isenthalpic Process

A process occurring at constant enthalpy ($h = \text{constant}$).

Isentropic Process

A process occurring at constant entropy ($s = \text{constant}$), which is both adiabatic and reversible.