4 Fundamental Thoughts

# 4 Fundamental Thoughts - "A Flowing Gas Continuum Mechanics...

This preview shows pages 1–5. Sign up to view the full content.

“A Flowing Gas” Continuum Mechanics Continuum Mechanics Fluid Mechanics Fluid Mechanics Solid Mechanics Solid Mechanics Aerodynamics Aerodynamics Hydrodynamics Hydrodynamics • Aerodynamics is a special subset of Fluid Mechanics, which in turn is a subset of Continuum Mechanics • Aerodynamics is a special subset of Fluid Mechanics, which in turn is a subset of Continuum Mechanics

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Four Aerodynamic Quantities • Pressure Force per unit area: N/m 2 , lb/in 2 , lb/ft 2 •Den s i ty Mass per unit volume: kg/m 3 , slug/ft 3 • Temperature Measure of average kinetic energy •Ve loc i ty A vector quantity: ft/s, m/s, mi/hr, km/hr • Pressure Force per unit area: N/m 2 , lb/in 2 , lb/ft 2 •Den s i ty Mass per unit volume:
Pressure • “Pressure is the normal force per unit area exerted on a surface due to the time rate of change of momentum of the gas molecules impacting on that surface.” • The concept of “force” arises from Newton’s 2 nd Law: F = m a or F = d(mv)/dt or F = m dv/dt mv is the momentum or linear momentum • Pressure varies from point to point p = lim dF/dA as dA 0 • Pressure depends on position and time: p = p(x,y,z,t) where t- dependence unsteady flow p = p(x,y,z) where no t- dependence steady flow • “Pressure is the normal force per unit area exerted on a surface due to the time rate of change of momentum of the gas molecules impacting on that surface.” • The concept of “force” arises from Newton’s 2 nd Law: F = m a or F = d(mv)/dt or F = m dv/dt mv is the momentum or linear momentum • Pressure varies from point to point p = lim dF/dA as dA 0 • Pressure depends on position and time: p = p(x,y,z,t) where t- dependence unsteady flow p = p(x,y,z) where no t- dependence steady flow dF dA gas B

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Density •“The densityof a substance (including a gas) is the mass of that substance per unit volume.” • The concept of density obviously combines the concepts of mass and volume • Density varies from point to point ρ = lim (dm/dv) as dv
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 15

4 Fundamental Thoughts - "A Flowing Gas Continuum Mechanics...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online