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FLOW FIELD SPECIFICATION

FLOW FIELD SPECIFICATION. Eulerian and Lagrangian descriptions:. Eulerian. Lagrangian. Velocity field and trajectories. Streamlines. Parallel (tangent) to the velocity vector → boundaries are streamlines. Represent velocity trajectories. slope of streamlines.

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FLOW FIELD SPECIFICATION

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  1. FLOW FIELD SPECIFICATION Eulerian and Lagrangian descriptions: Eulerian Lagrangian

  2. Velocity field and trajectories Streamlines Parallel (tangent) to the velocity vector → boundaries are streamlines. Represent velocity trajectories. slope of streamlines

  3. What can we say about these streamlines? www.me.bme.hu/~karolyi/results/advect/advection.html

  4. Pathlines Trajectory of an identified water parcel – represent one particle at different times. http://projects.ict.usc.edu/animation/fluidsim.htm (e.g. progressive vector diagrams)

  5. Streaklines Pathlines that move more than a single point through the flow. Represent multiple particles at one time. https://visualization.hpc.mil/wiki/Streaklines Effective way to identify flow discontinuities through large separation of the points in the Streakline. Streamlines = Pathlines = Streaklines if the flow is steady, i.e.,

  6. Stream function In two dimensional flow we can define a stream function Ψ, such that: A y What is the mass flux ρQ across the line AB? B If ABII to y, then Q = u dy http://www.atmos.albany.edu/student/gareth/diagnostics.html But in general AB can be defined by (dy,-dx), so that x

  7. If A and B are on the same streamline, then Q = 0, so Ψmust be a constant along a streamline. Another way to look at it: slope of streamlines Ψmust be a constant along a streamline.

  8. Differentiating following a fluid parcel advective local Adopting the Eulerian description, the rate of change of properties following a parcel:

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