Fluid Mechanics Exam I

Pascal’s Law

Pressure at a point is equal in all directions

Free Jet

Flow of liquid from a large reservoir. Describes when a fluid leaves out of a nozzle of diameter d with a velocity v. At this point P=0

Large tank

Velocity of the fluid does not change because the size of the reservoir is too large.

Flow Rate (Q)

=vA. To conserve mass, the inflow rate must equal the outflow rate.

Fluid

A substance that deforms continuously when acted upon by a shearing stress of any magnitude

Absolute Pressure

References ot a zero pressure

Gage Pressure

Referenced to local atmospheric pressure

Dynamic Viscosity (μ)

Fluid resistance to the flow, stickiness of fluid

Kinematic viscosity (v)

The ratio between dynamic viscosity to density

Newtonian Fluid

Shear stress is linear to shearing strain (Oil, Water)

Non-Newtonian fluid

Shear stress is not linear to shearing stress

Shear Thinning

Dynamic Viscosity decreases when shear rate increases. The harder fluid is shear, the less viscous it becomes (Paint)

Shear Thickening

Dynamic viscosity increases when shear increases. The harder the fluid is sheared, the most viscous it becomes (Quick sand, Corn starch in water)

2 Forces acting on an element

Surface (Pressure), & Body (Weight)

How to interchange fluid

y(oil)h(oil)=P(interface)=y(H2O)h(newH2O) solve for h(newH2O)

Streamlines

Lines that are tangent to the velocity vector in a steady flow field

Steady Flow

No change with time

Streamwise acceleration

Goes along the streamline

Normal Acceleration

Normal to streamline (Perpendicular)

Stagnation pressure

The largest pressure along the given streamline, represents the conversion of kinetic energy into pressure rise. Stagnation = Static + Dynamic

Fluid Kinematics

Mean motion regardless to what causes the motion, and the motion is characterized by velocity, distance, acceleration