# Complex potential

1. Mar 11, 2007

### dopey9

1. The problem statement, all variables and given/known data
Iv been given the complex potential equation ..iv been trying to split it into real and imaginary parts so i can find the streamfunction and potential for it...however the ln is making it difficult

2. Relevant equations

3. The attempt at a solution

iv tried taking out a factor of two from 2i +4 and raising it to the ln part....so i get ln (x+iy)^2...i expanded that but i still got imaginary parts inside

so i was wondering if anyone knows any other ways to split the equation into imaginary parts and real parts
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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Last edited: Mar 11, 2007
2. Mar 11, 2007

### Dick

You'll want to express x+iy in the form r*exp(i*theta) and then think about evaluating the log.

3. Mar 11, 2007

### dopey9

Thanks that makes sense..i got it in my notes but just dont when to apply it

4. Mar 11, 2007

### dopey9

streamline question

i was wondering if my u is right, as my problem deals with two dimensional inviscid steady potential flow and there are are various ways to find u = u(r,theta)er + v(r,theta)etheta

u= (-2/r)*er +(2/r)*etheta

and if so i was wondering how to sketch streamlines...using the previous question posted above i found that the speed of the particle was
u= (-2/r)*er +(2/r)*etheta

Last edited: Mar 11, 2007