Fluids Exam 2 Lsns 15-27

Pressure Distribution

It is the description of how pressure varies from point to point along a surface submerged in a fluid.

The pressure distribution is always……

Compressive and Normal to The Surface

What is the resultant force of a pressure distribution called?

The Resultant Hydrostatic Force

What is the name of the point that the Resultant Hydrostatic Force passes through?

Center of Pressure (CP)

Is the Center of Pressure the same for all pressure distributions?

No

What is Yc?

Yc is the distance from the Water Surface to the centroid of the panel

What is Hc?

Hc is the vertical distance from the Water Surface to the centroid of the panel

What is Ycp?

Ycp is the distance from the water surface to the center of pressure

What is the special case for a rectangular wall for Ycp?

Hcp= 2/3 Height (measured from WS)

Definition of Buoyancy

The ability of a body to float

What is Buoyant Force (Fb) equal to?

It is equal to the weight of the liquid that would be needed to fill the submerged volume. (Fb = y(Volume Displaced)

What is Archimedes’ Principle

When an object is partially or completely submerged in a fluid, it receives an upward force called buoyant force equal to the weight of the displaced fluid.

The line of action passes through the centroid of the displaced volume is called what?

Center of Buoyancy

What is a hydrometer used for?

To measure specific gravity of liquids, the depth of the hydrometer is correlated with the specific gravity of the fluid. A deeper depth means a lower specific gravity.

What orientation of Fb and CG will create a restoring couple?

Fb located above CG

What are streamlines?

They are used to visualize and describe flowing fluid, and are tangent to the velocity vectors throughout the flow field

What is a stagnation point?

A point on a static body at which the fluid decelerates and comes to rest

Describe Uniform Flow

The velocity is constant in magnitude and direction from point to point at each instant in time

Describe non-uniform flow

The velocity changes along a streamline at point to point at each instant at time in magnitude, direction, or both

Describe Steady Flow

the velocity is constant with time at all points in a velocity field

Describe Unsteady Flow

The velocity is changing at least at some points in the velocity field

Describe Laminar Flow

The well ordered state of flow in which adjacent fluid layers move smoothly with respect to each other. The flow occurs in layers or lamine

What type of velocity distribution-flow does laminar flow have?

A smooth parabolic velocity with no significant mixing of particles

Describe Turbulent Flow

Unsteady flow characterized by eddies of various sizes and intense mixing

What type of velocity distribution-flow does turbulent flow have?

It has a plug shaped velocity distribution because eddies mix the flow

Describe Inviscid Flow

Viscous effects do not significantly influence the flow, frictionless

Describe Viscous Flow

effects of viscosity are important, both Laminar and Turbulent are types of viscous flow

What is the Bernoulli principle based on?

The conservation of energy

What does the Bernoulli Equation state?

The sum of the pressure head, velocity head, and elevation head is constant along a streamline

What conditions are required for Bernoulli’s equation?

Homogeneous and Incompressible, Steady flow, Inviscid Flow, No mechanical devices to add or subtract energy

What is Volume Flow Rate?

The volume of fluid flowing past a section per unit time

What is Mass Flow Rate?

The mass of fluid flowing past a section per unit time

What is the control volume approach?

The method whereby a volume in the flow field is identified and analyze the flow within the volume

When can we use the continuity equation?

If no fluid is added, stored, or removed between sections 1 & 2

What type of flow is the continuity equation applied to?

Steady flow where the volume flow rate is the same at any section

What are the assumptions of the continuity equation?

Steady flow and incompressible fluid

What assumptions are applied for the energy equation?

Homogeneous and Incompressible, Steady, and Viscous Flow

What is a pitot-static tube?

It is a tool used to measure the fluid velocity by converting velocity into pressure

What makes up the total head?

The pressure head, elevation head, and velocity head

What makes up the piezometric head?

The pressure head and elevation head