T2:08 - Fluid Continuity Flashcards
(14 cards)
What principle underlies the continuity of fluid flow?
The principle of conservation of mass: mass entering a control volume equals mass leaving plus any accumulation.
What is the continuity equation for steady, incompressible flow?
A1 * u1 = A2 * u2, where A is area and u is average velocity.
What does ‘mean velocity’ refer to in fluid flow?
It is the average velocity across a cross-section used because actual velocity varies within real fluids.
How is fluid continuity applied at a pipe junction?
The sum of all incoming and outgoing mass flow rates must be zero.
How are flow directions handled in junction analysis?
Inflow is considered positive and outflow negative to balance the continuity equation.
What defines the momentum of a fluid?
Momentum is the product of mass and velocity of a fluid element.
What is required to change a fluid’s momentum?
A net force proportional to the rate of change of momentum.
State the basic momentum equation for fluid flow.
F = ṁ(v2 − v1), where F is force and ṁ is the mass flow rate.
What are dynamic forces in a flowing fluid?
Forces that result from fluid motion, in addition to pressure and gravitational forces.
How is the momentum equation used in 2D flow?
It is resolved into x and y components using velocity angles θ and φ.
How do you find the resultant force from momentum components?
By vector addition: Resultant = √(Fx² + Fy²).
What changes in 3D momentum analysis?
A third velocity and force component in the z-direction is included.
What are the three components of force in 3D fluid flow?
F1 from solid surfaces, F2 from body forces (e.g., gravity), and F3 from external fluid pressure.
How is the reaction force on a solid related to fluid force?
By Newton’s third law: R = -F1.
