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phenomena and correlations of flowmeters.pptx
- 1. EULERIAN AND LAGRANGIANFLUID FLOW APPROACH • Focus on overall/ average fluid flow passing over a fixed location • Example: observer sitting on the bank of a river and watching flow • Focus on individual fluid parcels and bubble-scale information • Example: observer sitting in a boat and follows the flow of river Eulerian flow Lagrangian flow
- 2. STREAM LINES, PATHLINES AND STREAK LINES • Streamlines: an imaginary curve or line in the flow field so that the tangent to the curve at any point represents the direction of the instantaneous velocity at that point • Stream lines can never intersect each other and can not be observed in experiments Streamlines around an air foil and upper lower stream tubes
- 3. STREAM LINE, PATHLINE AND STREAK LINE • Streakline: is the locus of the temporary locations of all particles that have passed though a fixed point in the flow field at any instant of time • can be observed in experimental flow visualization • Dye line Streak line used to visualize the flow around a car inside a wind tunnel
- 4. ONE’, TWO’’, THREE’’’DIMENSIONAL FLOW One dimensional flow: All the flow parameters may be expressed as functions of time and one space coordinate only Example: the fully-developed flow through a pipe
- 5. ONE’, TWO’’, THREE’’’DIMENSIONAL FLOW In reality, flow is never one-dimensional because viscosity causes the velocity to decrease to zero at the solid boundaries Two dimensional flow: All the flow parameters are functions of time and two space coordinates (say x and y)
- 6. ONE’, TWO’’, THREE’’’DIMENSIONAL FLOW Three dimensional flow: The hydrodynamic parameters are functions of three space coordinates and time.
- 7. BASIC LAWS OFCONSERVATION • Conservation of mass (continuity equation) • Conservation of momentum (Newton’s second law of motion) • Conservation of energy (First law of thermodynamics) • involve equation of state and fluid properties, physical properties etc.
- 8. CONSERVATION OF MASS– THE CONTINUITY EQUATION •
- 9. QUESTIONS • Find thedepth of point below sea water surface where the pressure intensity is 404.8 kN/m2 . The specific gravity of sea water is given to be 1.03. • Solution hint: Total pressure on the surface, P = Weight of liquid above the immersed surface = Specific weight of liquid * Volume of liquid = Specific weight of liquid * area of the surface * depth of the liquid OR Intensity of the pressure at the base (point) per unit area = sp. wt. * depth
- 10. QUESTIONS • A soapbubble 50 mm in diameter has an internal pressure in excess of the outside pressure of 30 N/mm2 . Calculate the surface tension in the film of the soap bubble. • Solution hint: Consider the equilibrium of the upper hemisphere of the drop, • the upward force on the plane face ABCD is , Fup = Pπr • the surface tension force acting downward along the • circumference (ABCD) = T 2πr • A soap bubble has two liquid surfaces in contact with air, one inside the bubble and another outside the bubble, at equilibrium, Pπr = T 2πr
- 11. BERNOULLI'S EQUATION • Bernoulli'sprinciple: " For a perfect incompressible liquid, flowing in a continuous stream, the total energy of a particle remains the same, while the particle moves from one point to another."
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- 16. VENTURI METER • Usesand applications: