Outward flux of a vector field

  • Thread starter DottZakapa
  • Start date
  • #1
DottZakapa
239
17
Homework Statement:
The out-flux of the vector field
F(x,y,z) = (sin(2x) + ye3z,(y + 1)2,−2z(y + cos(2x) + 3)
from the domain
D = {(x, y, z) ∈ R^3 : x^2 + y^2 + z^2 ≤ 1, x ≥ 0, y ≤ 0, z ≥ 0}
Relevant Equations:
flux of a vector field
My idea is to evaluate it using gauss theorem/divergence theorem.

so the divergence would be

## divF = (\cos (2x)2+2y+2-2z ( y+\cos (2x)+3) ) ##

is it correct?
In this way i'ma able to compute a triple integral on the volume given by the domain

## D = \left\{ (x, y, z) ∈ R^3 : x^2 + y^2 + z^2 ≤ 1, x ≥ 0, y ≤ 0, z ≥ 0 \right\} ##
then using spherical coordinates
##x= r cos\theta \sin\phi\\
y= r\sin\theta\sin\phi\\
z=r\sin\phi##
with the following boundaries

##0\leq\phi\leq\frac \pi 2##

##\frac {3\pi} {2}\leq\theta\leq 0##

then i do the substitution in the divergence and solve the integral

##\iiint_V divF r^2\sin\phi dr d\theta d\phi ##

am i doing it correctly or is there anything wrong?
 

Answers and Replies

  • #2
BvU
Science Advisor
Homework Helper
15,383
4,371
##\frac {3\pi} {2}\leq\theta\leq 0## ?
 
  • #3
BvU
Science Advisor
Homework Helper
15,383
4,371
##\nabla\cdot\vec F = (\cos (2x)2+2y+2-2z ( y+\cos (2x)+3) )##

##2z## ?
 
  • #4
DottZakapa
239
17
##\nabla\cdot\vec F = (\cos (2x)2+2y+2-2z ( y+\cos (2x)+3) )##

##2z## ?
Ops i did not notice
So
divF = -4
 
  • #5
DottZakapa
239
17
##\frac {3\pi} {2}\leq\theta\leq 0## ?
If that is not a correct bound then i did not understend how to find it.
If someone would be so kind to explain it
 
  • #6
BvU
Science Advisor
Homework Helper
15,383
4,371
If ##\theta \le 0 ## it can't be bigger than ##{3\over 2}\pi## :smile:
 
  • #7
DottZakapa
239
17
If ##\theta \le 0 ## it can't be bigger than ##{3\over 2}\pi## :smile:
So ##{3\over 2}\pi##to ##{2\pi}##
 

Suggested for: Outward flux of a vector field

  • Last Post
Replies
1
Views
449
Replies
6
Views
498
Replies
9
Views
425
  • Last Post
Replies
10
Views
373
Replies
8
Views
1K
Replies
4
Views
583
Replies
2
Views
943
Replies
2
Views
590
  • Last Post
Replies
6
Views
369
Top