# Beskjeder

According to the "Tid og sted" under GEF4500:

Avsluttende skriftlig eksamen

4. desember kl. 14:30 (3 timer).

* Store lesesal, gr. 2 Vilhelm Bjerknes hus

I've reserved room 5 from 1-3 pm on Monday. I guess that must be somewhere near room 7...

In problem 2, you will need an additional constraint at the wall. In addition to psi=0, also use the no-slip condition--- that v=d/dx psi=0

Note that the general solution to

d^4 psi/dx^4 - d/dx psi = 0

is

psi = c*1 + c*2 exp(x) + c*3 exp(-x/2) cos(sqrt(3) x/2) + c*4 exp(-x/2) sin(sqrt(3) x/2)

while the solution to;

d^4 psi/dx^4 + d/dx psi = 0

is

psi = c*1 + c*2 exp(-x) + c*3 exp(x/2) cos(sqrt(3) x/2) + c*4 exp(x/2) sin(sqrt(3) x/2)

In problem 3, it should read which profile is stable by Fjortofts if beta=0?

Also, the last profile SHOULD read:

U = 1/6 y^3 + 5/6 y

To evaluate Fjortoft's, set U_s equal to the value of U where d^2U/dy2 = 0

The argument in the exponential should have a minus sign in problem 1 on the 5th problem set.

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There's a problem downloading the class notes. I'm working on it...

Problem set 3: Assume that f=f_0 in problem 2 (so that df/dy=0).

There were two mistakes in problem 1 on problem set 2. The second order derivative should be with respect to **t**, not x, and below that it should be cos^3(t) rather than cos^3(x).

For psi*0 and psi*1, find only the particular solutions. Since we don't have boundary conditions, we ignore the homogeneous solutions.

Also: the sign on the RHS of equation 1 in problem 2 should be positive not negative.