Fluid Mechanics 1 Flashcards
What is Eularian/Laboratory description?
Observer fixed in space, flow passes by
What is Lagrangian/Material Description?
Observer is fixed to fluid particle, moves with flow
What is the material derivative?
Material rate of change expressed in Eularian frame of reference
Consists of local and convective part
d \phi / dt = (delta phi / delta t) + u * nabla phi
What are pathlines?
Trajectory of fluid particle
What are streamlines?
Integral curves of the instantaneous velocity field
given by dx_s,1 / u_1 = dx_s,2 / u_2 = dx_s,3/ u3
What is the integral formula for mass conservation?
dm/dt = \int_V (d\rho/dt)dV + \int_S (\rho u * ndS) = 0
What is the differential formula for mass conservation?
(\delta \rho / dt) + \nabla * (\rho * u ) = 0
What are properties of incompressible flow?
D\rho / dt = 0
div u = \nabla * u = \delta u / \delta x = 0
What is the pressure force in an ideal jet?
p = p_{\infty}
What does the momentum conservation equation consist of?
convective fluxes, pressure force, friction force, body forces, singular forces
What are the simplifications for the Brenoulli equation we use?
Steady flow and constant density, along streamline,
What is the critical reynolds number?
About 2300
What are the static state changes that occur after shock?
pressure increases
density increases
temperature increases
velocity decreases
speed of sound increases
entropy increases
What are stagnation state changes that occur after shock?
stagnation pressure decreases
stagnation density decreases
stagnation temperature remains the same
What is Knods number?
For telling if the continuum Model can be applied. Formula is lambbda / L where lambda is the mean free path and L is the characteristic length
