Pathline and Streamline problem

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Discussion Overview

The discussion revolves around a problem involving pathlines and streamlines in fluid dynamics, specifically focusing on finding streamlines at different time instances. Participants explore the mathematical relationships and equations involved in determining these streamlines.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • One participant expresses confusion regarding the velocity field and its representation, noting a lack of clarity in previous explanations.
  • Another participant suggests starting with a specific value (A=0) to simplify the problem and asks for the velocity vector at a given point.
  • A participant reports having found streamlines for t=0 and is uncertain about how to find them for t=1, mentioning an expected answer of e^(3/2).
  • There is a discussion about the components of the velocity vector and how they relate to the streamlines, with one participant questioning the choice of parameters.
  • Another participant points out the importance of visualizing fixed grid points to aid in understanding the problem and suggests that these points could lead to the expected answer.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the method for finding the streamlines at t=1, as there is ongoing uncertainty and differing interpretations of the equations involved.

Contextual Notes

There are unresolved assumptions regarding the definitions of variables and the specific forms of the velocity components. The discussion reflects a reliance on prior knowledge that may not be uniformly understood among participants.

Abigail1997
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Screen Shot 2016-07-27 at 17.55.55.png
1. Homework Statement

As above

Homework Equations


Not sure.

The Attempt at a Solution


I've only ever seen one of these problems and it was in the form of V=Axi-Ayj, so much simpler and even then it was poorly explained by the lecturer. I understand what a velocity field is but not much more.
 
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Hi, Abigail, :welcome:

Try A=0 to get started. The velocity vector at point ##(1,1)## is ?
 
statement, all variables and given/known data
I have completed question a, getting e^(t+((t^2)/4)) and e^t respectively and found the streamline for t=0, getting x=Cy, c being a constant- but am totally out of idea for finding it when t=1. I have been told the answer is e^3/2 but not sure how to get there

Homework Equations


dx/u=dy/v[/B]
first paragraph counts as an attempt at solution, I would say. (Choosing C as parameter is unfortunate, though, if the problem statement already has a C.)
Can't guess what u and v are; the components of ##\vec v## ?
You found the streamlines at t =0 from ##\vec v = Bx\hat\imath + Cy\hat\jmath##
Aren't the streamlines for t=1 given by simply substituting t=1 and doing the same thing ?
 
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BvU said:
first paragraph counts as an attempt at solution, I would say. (Choosing C as parameter is unfortunate, though, if the problem statement already has a C.)
Can't guess what u and v are; the components of ##\vec v## ?
You found the streamlines at t =0 from ##\vec v = Bx\hat\imath + Cy\hat\jmath##
Aren't the streamlines for t=1 given by simply substituting t=1 and doing the same thing ?

Yeah I realized that and changed it to D :) correct, u and v represent the x and y components of V. As for the subbing in t=1, that's what I thought but I cannot seem to get the correct answer (e^3/2) but I'm probably making a silly mistake somewhere and just can't see it
 
Check the non-moving dashes in the first picture here (watch out for headaches).
These dashes at fixed grid points you can draw for t=1 in your exercise. They should suggest the ##e^{3\over 2}##
 
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