Problem1:
A velocity field is given by
a) Find the equation of the streamline at t =t0 passing through the point (x0,y0).
b)
Obtain the path line of a fluid element which comes to (x0, y0) at t=t0.
c)
Show that, if A=0 and B=0 (i.e. steady flow), the streamline and path line coincide.
Solution:
a)
Streamline: Here Ux=(1+At +Bt2) and Uy=x.
Since the slope of the streamline (dy/dx) is the same as the slope (Uy/Ux) of the velocity vector.
Therefore
Integrating this with the condition x=x0, y=y0 gives
the Streamline
b) Path line: Consider a fluid element passing through (x0, y0) at t=t0. Its co-ordinates (x,y) at other values of t (which define the pathline) can
be expressed as
Since,
And,
Integrating the first equation gives,
Now,

These equations of x, y are
parametric equation of path line.
The time t can be eliminated between them to give an equation for y in terms of x.
c) When A=B=0, then the equation of streamline becomes
and the parametric equations of the path line becomes;
Therefore,
which is equivalent to streamline.
Problem2:
A two-dimensional flow field is defined as
Define the equation of Streamline passing through the point (1,0)
Solution:
The equation of Streamline is
or,
Hence,
or,
Integration of equation above gives
where k is constant
For stream line passing through (1,0) , 
Hence, the required equation is: 
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