Week 5 Flashcards
What are the three basic approaches to analysing arbitrary flow problems?
- Control volume (large-scale) analysis
- Differential (small-scale) analysis
- Experimental (dimensional) analysis
Why can the conservation of mass for an infinitesimal control volume also called an equation of continuity?
Requires no
assumptions except that the density and velocity are contiuum
functions.
What is assumed in steady compressible flow regarding properties?
All properties are functions of position only.
What is the assumption made in incompressible flow?
Density changes are negligible.
What are the two types of forces considered in linear momentum relations?
- Body forces
- Surface forces
What are the components of surface forces in fluid mechanics?
- Hydrostatic pressure
- Viscous stresses due to motion with velocity gradients
What does the linear momentum relation with forces per unit element volume express?
Gravity force per unit volume + pressure force per unit volume + viscous force per unit volume = density x acceleration.
What is Euler’s equation used for?
To describe inviscid flow where viscous stresses are assumed to be zero.
What are the Navier-Stokes equations used for?
To describe incompressible flow for a Newtonian fluid with constant density and viscosity.
What does the term ‘no slip’ refer to in fluid mechanics?
The condition where fluid particles do not slip along the wall.
