Week 1 Flashcards
What is Transport Phenomena?
Transport phenomena (TP) is the study of the transfer of mass, momentum, and energy within a fluid and their exchange between systems.
What are the two physical mechanisms involved in transport processes?
- Diffusion
- Convection
Define diffusion in the context of transport phenomena.
Diffusion is the random motion of molecules caused by molecular collisions, resulting in net movement down a concentration gradient. Rapid and efficient over short distances.
Define convection in the context of transport phenomena.
Convection is transport driven by the bulk motion of fluids (flow), often dominating in systems with significant flow.
What are the three common thermodynamic properties of a fluid?
- Pressure
- Density
- Temperature
Give two transport properties.
*coefficient of viscosity
*thermal conductivity
What is the principle of dimensional homogeneity?
All additive terms in a physical equation must have the same dimensions.
What is a flux in transport phenomena?
A flux is the amount of a transported quantity passing through a unit area per unit time, with both magnitude and direction.
What are the recommended steps for problem-solving in transport phenomena?
- Read and restate the problem
- Gather needed property data
- Understand what is asked
- Make a detailed sketch
- List assumptions
- Find an algebraic solution
- Report the solution with proper units and significant figures
What defines a fluid?
A fluid is matter that deforms indefinitely under an applied shear stress. A force is required to maintain continuous deformation (i.e. flow).
How is matter classified in fluid mechanics?
*fluid
*solid
Based on the mechanical properties not chemical - specifically the reaction of matter to applied shear stress.
What is shear stress?
Tangential stress
Define an elastic solid..
Remains at rest in its
deformed state - in equilibrium against
the deforming force.
What are the two types of fluids based on cohesive forces?
- Liquids
- Gases
What is the hydrostatic stress condition?
A fluid at rest must be in a state of zero shear stress.
What is the difference between liquids and gases in terms of molecular spacing?
- Liquids: closer molecules, stronger cohesive forces. Form a free surface in a gravitational field
- Gases: widely spaced molecules with little to no cohesion. Cannot form a free surface.
What is the continuum approach in fluid dynamics?
*The continuum approach treats fluids as continuous bodies rather than discrete molecules, allowing the use of continuous functions for macroscopic properties.
*These pieces are called fluid elements.
What is viscosity?
Viscosity quantifies a fluid’s resistance to flow.
What is the no-slip condition in fluid mechanics?
The no-slip condition states that the fluid velocity is zero relative to the wall.
Define dimension.
The measure by which a physical variable is expressed quantitatively.
Define unit.
A particular way of attaching a number to the quantitative dimension.
True or False: All equations in fluid mechanics must be dimensionally consistent.
True
What are the four primary dimensions in fluid mechanics?
- Length
- Mass
- Time
- Temperature
When is the continuum approach a valid assumption?
If fluid elements are large compared to the microscopic scale but small relative to the macroscopic scale.
